MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Current Opinion in Neurobiology' source. Thu, 02 Feb 2012 20:44:25 +0100 http://www.medworm.com/index.php?rid=5627590&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22265243%26dopt%3DAbstract Authors: Bee MA Abstract Sound source perception refers to the auditory system's ability to parse incoming sensory information into coherent representations of distinct sound sources in the environment. Such abilities are no doubt key to successful communication in many taxa, but we know little about their function in animal communication systems. For anuran amphibians (frogs and toads), social and reproductive behaviors depend on a listener's ability to hear and identify sound signals amid high levels of background noise in acoustically cluttered environments. Recent neuroethological studies are revealing how frogs parse these complex acoustic scenes to identify individual calls in noisy breeding choruses. Current evidence highlights some interesting similarities and differences i... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5627590 Thu, 19 Jan 2012 05:00:00 +0100 5627590 http://www.medworm.com/index.php?rid=5607503&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22244741%26dopt%3DAbstract Authors: Nordström K Abstract Despite being equipped with low-resolution eyes and tiny brains, many insects show exquisite abilities to detect and pursue targets even in highly textured surrounds. Target tracking behavior is subserved by neurons that are sharply tuned to the motion of small high-contrast targets. These neurons respond robustly to target motion, even against self-generated optic flow. A recent model, supported by neurophysiology, generates target selectivity by being sharply tuned to the unique spatiotemporal profile associated with target motion. Target neurons are likely connected in a complex network where some provide more direct output to behavior, whereas others serve an inter-regulatory role. These interactions may regulate attention and aid in the robust de... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5607503 Thu, 12 Jan 2012 05:00:00 +0100 5607503 http://www.medworm.com/index.php?rid=5607502&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22244742%26dopt%3DAbstract Authors: Wiltschko W, Wiltschko R Abstract The advancing development of tracking techniques has led to fascinating new insights into avian migration, documenting the immense diversity, complexity, and flexibility of this phenomenon. Tracking studies so far have confirmed many findings from ringing recoveries and cage studies, for example, the change from flying innate compass courses in the first migration to true navigation, as experienced migrants head toward familiar goals. First attempts to analyze the navigational mechanisms by tracking manipulated migrants indicate strong parallels to those of homing pigeons. Findings suggesting that the magnetic compass of migrants is regularly calibrated by the pattern of polarized light could not be replicated with a number of other birds,... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5607502 Thu, 12 Jan 2012 05:00:00 +0100 5607502 http://www.medworm.com/index.php?rid=5581555&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237048%26dopt%3DAbstract Authors: Kerr JN, Nimmerjahn A Abstract Uncovering the relationships between animal behavior and cellular activity in the brain has been one of the key aims of neuroscience research for decades, and still remains so. Electrophysiological approaches have enabled sparse sampling from electrically excitable cells in freely moving animals that has led to the identification of important phenomena such as place, grid and head-direction cells. Optical imaging in combination with newly developed labeling approaches now allows minimally invasive and comprehensive sampling from dense networks of electrically and chemically excitable cells such as neurons and glia during self-determined behavior. To achieve this two main imaging avenues have been followed: Optical recordings in head-restraine... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581555 Mon, 09 Jan 2012 05:00:00 +0100 5581555 http://www.medworm.com/index.php?rid=5581556&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22226994%26dopt%3DAbstract Authors: Foster DJ, Knierim JJ Abstract The hippocampus has long been associated with navigation and spatial representations, but it has been difficult to link directly the neurophysiological correlates of hippocampal place cells with navigational planning and action. In recent years, large-scale population recordings of place cells have revealed that spatial sequences are stored and activated in ways that may support navigational strategies. Plasticity mechanisms allow the hippocampus to store learned sequences of locations that may allow predictions of future locations based on past experience. These sequences can also be activated during navigational behavior in ways that may allow the animal to learn trajectories toward goals. Task-dependent alterations in place cell firing pat... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581556 Fri, 06 Jan 2012 05:00:00 +0100 5581556 http://www.medworm.com/index.php?rid=5581559&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22226428%26dopt%3DAbstract Authors: Yager DD Abstract Echolocating bats detect prey using ultrasonic pulses, and many nocturnally flying insects effectively detect and evade these predators through sensitive ultrasonic hearing. Many eared insects can use the intensity of the predator-generated ultrasound and the stereotyped progression of bat echolocation pulse rate to assess risk level. Effective responses can vary from gentle turns away from the threat (low risk) to sudden random flight and dives (highest risk). Recent research with eared moths shows that males will balance immediate bat predation risk against reproductive opportunity as judged by the strength and quality of conspecific pheromones present. Ultrasound exposure may, in fact, bias such decisions for up to 24 hours through plasticity in the CN... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581559 Thu, 05 Jan 2012 05:00:00 +0100 5581559 http://www.medworm.com/index.php?rid=5581558&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22226513%26dopt%3DAbstract Authors: Pirri JK, Alkema MJ Abstract Escape behaviors are crucial to survive predator encounters. Touch to the head of Caenorhabditis elegans induces an escape response where the animal rapidly backs away from the stimulus and suppresses foraging head movements. The coordination of head and body movements facilitates escape from predacious fungi that cohabitate with nematodes in organic debris. An appreciation of the natural habitat of laboratory organisms, like C. elegans, enables a comprehensive neuroethological analysis of behavior. In this review we discuss the neuronal mechanisms and the ecological significance of the C. elegans touch response. PMID: 22226513 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581558 Wed, 04 Jan 2012 05:00:00 +0100 5581558 http://www.medworm.com/index.php?rid=5581557&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22226514%26dopt%3DAbstract Authors: Card GM Abstract Escape behaviors are, by necessity, fast and robust, making them excellent systems with which to study the neural basis of behavior. This is especially true in insects, which have comparatively tractable nervous systems and members who are amenable to manipulation with genetic tools. Recent technical developments in high-speed video reveal that, despite their short duration, insect escape behaviors are more complex than previously appreciated. For example, before initiating an escape jump, a fly performs sophisticated posture and stimulus-dependent preparatory leg movements that enable it to jump away from a looming threat. This newfound flexibility raises the question of how the nervous system generates a behavior that is both rapid and flexible. Recordin... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581557 Wed, 04 Jan 2012 05:00:00 +0100 5581557 http://www.medworm.com/index.php?rid=5581563&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221862%26dopt%3DAbstract Authors: Helmstaedter M, Mitra PP Abstract The connectivity architecture of neuronal circuits is essential to understand how brains work, yet our knowledge about the neuronal wiring diagrams remains limited and partial. Technical breakthroughs in labeling and imaging methods starting more than a century ago have advanced knowledge in the field. However, the volume of data associated with imaging a whole brain or a significant fraction thereof, with electron or light microscopy, has only recently become amenable to digital storage and analysis. A mouse brain imaged at light-microscopic resolution is about a terabyte of data, and 1mm(3) of the brain at EM resolution is about half a petabyte. This has given rise to a new field of research, computational analysis of large-scale neuroan... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581563 Tue, 03 Jan 2012 05:00:00 +0100 5581563 http://www.medworm.com/index.php?rid=5581562&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221863%26dopt%3DAbstract Authors: Zeil J Abstract The ability to learn the location of places in the world and to revisit them repeatedly is crucial for all aspects of animal life on earth. It underpins animal foraging, predator avoidance, territoriality, mating, nest construction and parental care. Much theoretical and experimental progress has recently been made in identifying the sensory cues and the computational mechanisms that allow insects (and robots) to find their way back to places, while the neurobiological mechanisms underlying navigational abilities are beginning to be unravelled in vertebrate and invertebrate models. Studying visual homing in insects is interesting, because they allow experimentation and view-reconstruction under natural conditions, because they are likely to have evolved par... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581562 Tue, 03 Jan 2012 05:00:00 +0100 5581562 http://www.medworm.com/index.php?rid=5581561&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221864%26dopt%3DAbstract Authors: Gaudry Q, Nagel KI, Wilson RI Abstract Navigating toward (or away from) a remote odor source is a challenging problem that requires integrating olfactory information with visual and mechanosensory cues. Drosophila melanogaster is a useful organism for studying the neural mechanisms of these navigation behaviors. There are a wealth of genetic tools in this organism, as well as a history of inventive behavioral experiments. There is also a large and growing literature in Drosophila on the neural coding of olfactory, visual, and mechanosensory stimuli. Here we review recent progress in understanding how these stimulus modalities are encoded in the Drosophila nervous system. We also discuss what strategies a fly might use to navigate in a natural olfactory landscape while maki... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581561 Tue, 03 Jan 2012 05:00:00 +0100 5581561 http://www.medworm.com/index.php?rid=5581560&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22221865%26dopt%3DAbstract Authors: Wickersham IR, Feinberg EH Abstract Understanding the brain will require unraveling its synaptic circuitry, but methods that can reliably identify connected neurons are often excruciatingly slow. Although light microscopy can provide much higher throughput, synapses are smaller than the diffraction limit and cannot readily be assigned to particular presynaptic and postsynaptic cells without specialized labeling methods. Here we review the ongoing development of techniques that allow direct imaging of neural networks by specifically marking connected cells or their synapses. PMID: 22221865 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5581560 Tue, 03 Jan 2012 05:00:00 +0100 5581560 http://www.medworm.com/index.php?rid=5569977&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22217700%26dopt%3DAbstract Authors: Anggono V, Huganir RL Abstract AMPA receptors (AMPARs) mediate the majority of fast excitatory synaptic transmission in the brain. Dynamic changes in neuronal synaptic efficacy, termed synaptic plasticity, are thought to underlie information coding and storage in learning and memory. One major mechanism that regulates synaptic strength involves the tightly regulated trafficking of AMPARs into and out of synapses. The life cycle of AMPARs from their biosynthesis, membrane trafficking, and synaptic targeting to their degradation are controlled by a series of orchestrated interactions with numerous intracellular regulatory proteins. Here we review recent progress made toward the understanding the regulation of AMPAR trafficking, focusing on the roles of several key intracellu... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5569977 Mon, 02 Jan 2012 05:00:00 +0100 5569977 http://www.medworm.com/index.php?rid=5569978&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209216%26dopt%3DAbstract Authors: Vaziri A, Emiliani V Abstract Optogenetics has been revolutionizing circuit neuroscience in the last few years. Optical methods combined with genetics and molecular techniques have provided new tools for stimulation of neurons, which hold great promise to provide a solution to the circuit mapping problem and more generally provide us with the ability to artificially control the natural stimulus space. Nevertheless, until very recently almost all applications of optogenetics have been based on relatively simple optical schemes mainly used for inducing population activity in neuronal assembles. In this context, alternative optical schemes that enhance the spatial or temporal resolution of excitation and allow for flexible and arbitrary generation of light patterns have all s... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5569978 Thu, 29 Dec 2011 05:00:00 +0100 5569978 http://www.medworm.com/index.php?rid=5569980&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209039%26dopt%3DAbstract Authors: Catania KC Abstract A number of predators depend heavily on tactile cues for pursuing and capturing prey. Here I describe and discuss the whiskers of carnivorous grasshopper mice and shrews, the sensory rays of the star-nosed mole, and the tactile appendages of the tentacled snake. These diverse sensors are accompanied by remarkable corresponding specializations in the central nervous system. But understanding their function and the significance of the central nervous system correlates requires the careful documentation of behavior inherent to a neuroethological approach. PMID: 22209039 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5569980 Wed, 28 Dec 2011 05:00:00 +0100 5569980 http://www.medworm.com/index.php?rid=5569979&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209040%26dopt%3DAbstract Authors: Brecht M, Freiwald WA Abstract Facial interactions are prominent behaviors in primates. Primate facial signaling, which includes the expression of emotions, mimicking of facial movements, and gaze interactions, is visually dominated. Correspondingly, in primate brains an elaborate network of face processing areas exists within visual cortex. But other mammals also communicate through facial interactions using additional sensory modalities. In rodents, multisensory facial interactions are involved in aggressive behaviors and social transmission of food preferences. The eusocial naked mole-rat, whose face is dominated by prominent incisors, uses facial aggression to enforce reproductive suppression. In burrow-living mammals like the naked mole-rat in particular, and in roden... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5569979 Wed, 28 Dec 2011 05:00:00 +0100 5569979 http://www.medworm.com/index.php?rid=5553507&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22196925%26dopt%3DAbstract Authors: Schuster S Abstract Decision-making networks must be tuned according to the rules that govern which action will be rewarded for a given constellation of current sensory information. Somehow these rules must be implemented in the networks that translate the sensory cues to actions but the nature of this representation is enigmatic. Recent findings suggest that Mauthner-associated networks in some fish can govern surprisingly sophisticated and plastic decisions in which the rules of prey motion govern what speed and direction must be selected to be at the right point at the right time. With the key cellular players individually identifiable, fish can help us to discover the nature of how rules are represented in decision-making circuitry of the vertebrate brain. PMID: 22... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5553507 Thu, 22 Dec 2011 05:00:00 +0100 5553507 http://www.medworm.com/index.php?rid=5553508&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22195994%26dopt%3DAbstract Authors: Olberg RM Abstract Interacting with a moving object poses a computational problem for an animal's nervous system. This problem has been elegantly solved by the dragonfly, a formidable visual predator on flying insects. The dragonfly computes an interception flight trajectory and steers to maintain it during its prey-pursuit flight. This review summarizes current knowledge about pursuit behavior and neurons thought to control interception in the dragonfly. When understood, this system has the potential for explaining how a small group of neurons can control complex interactions with moving objects. PMID: 22195994 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5553508 Wed, 21 Dec 2011 05:00:00 +0100 5553508 http://www.medworm.com/index.php?rid=5540013&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22177596%26dopt%3DAbstract Authors: Deschênes M, Moore J, Kleinfeld D Abstract Sniffing and whisking are two rhythmic orofacial motor activities that enable rodents to localize and track objects in their environment. They have related temporal dynamics, possibly as a result of both shared musculature and shared sensory tasks. Sniffing and whisking also constitute the overt expression of an animal's anticipation of a reward. Yet, the neuronal mechanisms that underlie the control of these behaviors have not been established. Here, we review the similarities between sniffing and whisking and suggest that such similarities indicate a mechanistic link between these two rhythmic exploratory behaviors. PMID: 22177596 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5540013 Thu, 15 Dec 2011 05:00:00 +0100 5540013 http://www.medworm.com/index.php?rid=5540014&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22176799%26dopt%3DAbstract Authors: Hemmi JM, Tomsic D Abstract A major challenge in neurobiology is to understand how brains function in animals behaving in the complexity of their natural environment. Progress will depend on our ability to correctly interpret results from laboratory experiments in the light of information processing demands identified by studying the organization of behaviour and the flow of information in naturally behaving animals. Predator avoidance responses of semi-terrestrial crabs offer an excellent opportunity for such an approach. We review here findings from two distinct lines of research: (1) Field studies which have characterized the structure and context of escape behaviour to real and dummy predators, and (2) Laboratory studies which have used computer-simulated images and in... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5540014 Wed, 14 Dec 2011 05:00:00 +0100 5540014 http://www.medworm.com/index.php?rid=5518469&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22169055%26dopt%3DAbstract Authors: Gomez-Marin A, Louis M Abstract The fruit fly Drosophila larva demonstrates a sophisticated repertoire of behavior under the control of a numerically simple neural system. Historically, the stereotyped responses of larvae to light and odors captivated the attention of biologists. More recently, the sensory receptors responsible for chemosensation, thermosensation, and vision have been identified. While our understanding of the molecular logic of perception has clearly progressed, little is known about the neural and computational mechanisms guiding movement in sensory gradients. Here we review evidence that larvae orient based on active sensation-a feature distinct from the strategies used by simpler model organisms. Reorientation maneuvers are controlled by the spatiotemp... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5518469 Mon, 12 Dec 2011 05:00:00 +0100 5518469 http://www.medworm.com/index.php?rid=5518470&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22154565%26dopt%3DAbstract Authors: Merlin C, Heinze S, Reppert SM Abstract Long-distance migration is a strategy some animals use to survive a seasonally changing environment. To reach favorable grounds, migratory animals have evolved sophisticated navigational mechanisms that rely on a map and compasses. In migratory insects, the existence of a map sense (sense of position) remains poorly understood, but recent work has provided new insights into the mechanisms some compasses use for maintaining a constant bearing during long-distance navigation. The best-studied directional strategy relies on a time-compensated sun compass, used by diurnal insects, for which neural circuits have begun to be delineated. Yet, a growing body of evidence suggests that migratory insects may also rely on other compasses that us... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5518470 Thu, 08 Dec 2011 05:00:00 +0100 5518470 http://www.medworm.com/index.php?rid=5518471&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22138559%26dopt%3DAbstract Authors: Dombeck DA, Reiser MB Abstract Virtual reality (VR) holds great promise as a tool to study the neural circuitry underlying animal behaviors. Here, we discuss the advantages of VR and the experimental paradigms and technologies that enable closed loop behavioral experiments. We review recent results from VR research in genetic model organisms where the potential combination of rich behaviors, genetic tools and cutting edge neural recording techniques are leading to breakthroughs in our understanding of the neural basis of behavior. We also discuss several key issues to consider when performing VR experiments and provide an outlook for the future of this exciting experimental toolkit. PMID: 22138559 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobio... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5518471 Fri, 02 Dec 2011 05:00:00 +0100 5518471 http://www.medworm.com/index.php?rid=5518474&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22137100%26dopt%3DAbstract Authors: Steck K Abstract How is an ant-equipped with a brain that barely exceeds the size of a pinhead-capable of achieving navigational marvels? Even though evidences suggest that navigation is a multimodal process, ants heavily depend on olfactory cues-of pheromonal and non-pheromonal nature-for foraging and orientation. Recent studies have directed their attention to the efficiency of pheromone trail networks. Advances in neurophysiological techniques make it possible to investigate trail pheromone processing in the ant's brain. In addition to relying on pheromone odours, ants also make use of volatiles emanating from the nest surroundings. Deposited in the vicinity of the nest, these home-range markings help the ants to home after a foraging run. Furthermore, olfactory landmar... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5518474 Thu, 01 Dec 2011 05:00:00 +0100 5518474 http://www.medworm.com/index.php?rid=5518472&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22137567%26dopt%3DAbstract Authors: Tschida K, Mooney R Abstract Auditory experience is critical for the acquisition and maintenance of learned vocalizations in both humans and songbirds. Despite the central role of auditory feedback in vocal learning and maintenance, where and how auditory feedback affects neural circuits important to vocal control remain poorly understood. Recent studies of singing birds have uncovered neural mechanisms by which feedback perturbations affect vocal plasticity and also have identified feedback-sensitive neurons at or near sites of auditory and vocal motor interaction. Additionally, recent studies in marmosets have underscored that even in the absence of vocal learning, vocalization remains flexible in the face of changing acoustical environments, pointing to rapid interactio... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5518472 Thu, 01 Dec 2011 05:00:00 +0100 5518472 http://www.medworm.com/index.php?rid=5518473&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22137566%26dopt%3DAbstract Authors: Lohmann KJ, Putman NF, Lohmann CM Abstract Young loggerhead sea turtles (Caretta caretta) from eastern Florida, U.S.A., undertake a transoceanic migration in which they gradually circle the North Atlantic Ocean before returning to the North American coast. Hatchlings in the open sea are guided at least partly by a 'magnetic map' in which regional magnetic fields function as navigational markers and elicit changes in swimming direction at crucial locations along the migratory route. The magnetic map exists in turtles that have never migrated and thus appears to be inherited. Turtles derive both longitudinal and latitudinal information from the Earth's field, most likely by exploiting unique combinations of field inclination and intensity that occur in different geographic a... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5518473 Wed, 30 Nov 2011 05:00:00 +0100 5518473 http://www.medworm.com/index.php?rid=5465265&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22129781%26dopt%3DAbstract Authors: Datta SR, Patterson GH Abstract The development of advanced optical methods has played a key role in propelling progress in neurobiology. Genetically-encoded fluorescent molecules found in nature have enabled labeling of individual neurons to study their physiology and anatomy. Here we discuss the recent use of both native and synthetic optical highlighter proteins to address key problems in neurobiology, including questions relevant to synaptic function, neuroanatomy, and the organization of neural circuits. PMID: 22129781 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465265 Mon, 28 Nov 2011 05:00:00 +0100 5465265 http://www.medworm.com/index.php?rid=5465271&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119141%26dopt%3DAbstract Authors: Lois C, Groves JO Abstract The past few decades have seen the field of genetic engineering evolve at a rapid pace, with neuroscientists now equipped with a wide range of tools for the manipulation of an animal's genome in order to study brain function. However, the number of species to which these technologies have been applied, namely the fruit fly, C. elegans, zebrafish and mouse, remains relatively few. This review will discuss the variety of approaches to genetic modification that have been developed in such traditional 'genetic systems', and highlight the progress that has been made to translate these technologies to alternative species such as rats, monkeys and birds, where certain neurobiological questions may be better studied. PMID: 22119141 [PubMed - as suppl... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465271 Thu, 24 Nov 2011 05:00:00 +0100 5465271 http://www.medworm.com/index.php?rid=5465270&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119142%26dopt%3DAbstract Authors: Schaefer AT, Claridge-Chang A Abstract Genetics' demand for increased throughput is driving automatization of behavior analysis far beyond experimental workhorses like circadian monitors and the operant conditioning box. However, the new automation is not just faster: it is also allowing new kinds of experiments, many of which erase the boundaries of the traditional neuroscience disciplines (psychology, ethology and physiology) while producing insight into problems that were otherwise opaque. Ironically, a central theme of current automatization is to improve observation of animals in increasingly naturalistic environments. This is not just a return to 19th century priorities: the new observational methods provide unprecedented quantitation of actions and ever-closer integ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465270 Thu, 24 Nov 2011 05:00:00 +0100 5465270 http://www.medworm.com/index.php?rid=5465269&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119143%26dopt%3DAbstract Authors: Wulff P, Arenkiel BR Abstract Toward the functional dissection of neuronal circuits, a number of new genetic tools have been developed that enable rapid and reversible manipulation of genetically defined neuronal subtypes in intact mammalian brain circuits. Alongside the breakthrough technology of optogenetics, receptor-ligand pairs provide complementary approaches to modulate neuronal activity using chemical genetics. PMID: 22119143 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465269 Thu, 24 Nov 2011 05:00:00 +0100 5465269 http://www.medworm.com/index.php?rid=5465268&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119144%26dopt%3DAbstract Authors: Ibañez-Tallon I, Nitabach MN Abstract Tethering genetically encoded peptide toxins or ligands close to their point of activity at the cell plasma membrane provides a new approach to the study of cell networks and neuronal circuits, as it allows selective targeting of specific cell populations, enhances the working concentration of the ligand or blocker peptide, and permits the engineering of a large variety of t-peptides (e.g., including use of fluorescent markers, viral vectors and point mutation variants). This review describes the development of tethered toxins (t-toxins) and peptides derived from the identification of the cell surface nicotinic acetylcholine receptor (nAChR) modulator lynx1, the existence of related endogenous cell surface modulators of nAChR and AMPA... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465268 Thu, 24 Nov 2011 05:00:00 +0100 5465268 http://www.medworm.com/index.php?rid=5465267&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119320%26dopt%3DAbstract Authors: Bernstein JG, Garrity PA, Boyden ES Abstract In recent years, interest has grown in the ability to manipulate, in a temporally precise fashion, the electrical activity of specific neurons embedded within densely wired brain circuits, in order to reveal how specific neurons subserve behaviors and neural computations, and to open up new horizons on the clinical treatment of brain disorders. Technologies that enable temporally precise control of electrical activity of specific neurons, and not these neurons' neighbors-whose cell bodies or processes might be just tens to hundreds of nanometers away-must involve two components. First, they require as a trigger a transient pulse of energy that supports the temporal precision of the control. Second, they require a molecular sensi... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465267 Wed, 23 Nov 2011 05:00:00 +0100 5465267 http://www.medworm.com/index.php?rid=5465266&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119321%26dopt%3DAbstract Authors: Briggman KL, Bock DD Abstract The last decade has seen a rapid increase in the number of tools to acquire volume electron microscopy (EM) data. Several new scanning EM (SEM) imaging methods have emerged, and classical transmission EM (TEM) methods are being scaled up and automated. Here we summarize the new methods for acquiring large EM volumes, and discuss the tradeoffs in terms of resolution, acquisition speed, and reliability. We then assess each method's applicability to the problem of reconstructing anatomical connectivity between neurons, considering both the current capabilities and future prospects of the method. Finally, we argue that neuronal 'wiring diagrams' are likely necessary, but not sufficient, to understand the operation of most neuronal circuits: volume... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465266 Wed, 23 Nov 2011 05:00:00 +0100 5465266 http://www.medworm.com/index.php?rid=5465272&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22104761%26dopt%3DAbstract Authors: Looger LL, Griesbeck O Abstract Recording activity from identified populations of neurons is a central goal of neuroscience. Changes in membrane depolarization, particularly action potentials, are the most important features of neural physiology to extract, although ions, neurotransmitters, neuromodulators, second messengers, and the activation state of specific proteins are also crucial. Modern fluorescence microscopy provides the basis for such activity mapping, through multi-photon imaging and other optical schemes. Probes remain the rate-limiting step for progress in this field: they should be bright and photostable, and ideally come in multiple colors. Only protein-based reagents permit chronic imaging from genetically specified cells. Here we review recent progress i... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465272 Sat, 19 Nov 2011 05:00:00 +0100 5465272 http://www.medworm.com/index.php?rid=5465273&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22100874%26dopt%3DAbstract Authors: Nelson S, Ashe K PMID: 22100874 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5465273 Thu, 17 Nov 2011 05:00:00 +0100 5465273 http://www.medworm.com/index.php?rid=5428911&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088391%26dopt%3DAbstract Authors: Bourne JN, Harris KM Abstract Structural plasticity of dendritic spines and synapses is an essential mechanism to sustain long lasting changes in the brain with learning and experience. The use of electron microscopy over the last several decades has advanced our understanding of the magnitude and extent of structural plasticity at a nanoscale resolution. In particular, serial section electron microscopy (ssEM) provides accurate measurements of plasticity-related changes in synaptic size and density and distribution of key cellular resources such as polyribosomes, smooth endoplasmic reticulum, and synaptic vesicles. Careful attention to experimental and analytical approaches ensures correct interpretation of ultrastructural data and has begun to reveal the degree to which ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5428911 Mon, 14 Nov 2011 05:00:00 +0100 5428911 http://www.medworm.com/index.php?rid=5428910&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088392%26dopt%3DAbstract Authors: Jeong DC, Tsai PS, Kleinfeld D Abstract The controlled cutting of tissue with laser light is a natural technology to combine with automated stereotaxic surgery. A central challenge is to cut hard tissue, such as bone, without inducing damage to juxtaposed soft tissue, such as nerve and dura. We review past work that demonstrates the feasibility of such control through the use of ultrafast laser light to both cut and generate optical feedback signals via second harmonic generation and laser induced plasma spectra. PMID: 22088392 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5428910 Mon, 14 Nov 2011 05:00:00 +0100 5428910 http://www.medworm.com/index.php?rid=5428913&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079494%26dopt%3DAbstract Authors: Lisman J Abstract What causes the positive, negative, and cognitive symptoms of schizophrenia? The importance of circuits is underscored by the finding that no single gene contributes strongly to the disease. Thus, some circuit abnormality to which many proteins can contribute is the likely cause. There are several major hypotheses regarding the circuitry involved: first, a change in the balance of excitation/inhibition in the prefrontal cortex (PFC); second, abnormal EEG oscillations in the gamma range; third, an increase in theta/delta EEG power related to changes in the thalamus (particularly midline nuclei); fourth, hyperactivity in the hippocampus and consequent dopamine hyperfunction; and fifth, deficits in corollary discharge. Evidence for these hypotheses will be r... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5428913 Fri, 11 Nov 2011 05:00:00 +0100 5428913 http://www.medworm.com/index.php?rid=5428912&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079495%26dopt%3DAbstract Authors: Gallagher M, Koh MT Abstract This review is focused on specific circuits of the medial temporal lobe that have become better understood in recent years for their computational properties contributing to episodic memory and to memory impairment associated with aging and other risk for AD. The layer II neurons in the entorhinal cortex and their targets in the dentate gyrus and CA3 region of hippocampus comprise a system that rapidly encodes representations that are distinct from prior memories. Frank neuron loss in the entorhinal cortex is specific for AD, and related structural and functional changes across the network comprised of the entorhinal cortex and the dentate/CA3 regions hold promise for predicting progression on the path to AD. PMID: 22079495 [PubMed - as sup... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5428912 Fri, 11 Nov 2011 05:00:00 +0100 5428912 http://www.medworm.com/index.php?rid=5383867&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22054923%26dopt%3DAbstract Authors: Craig TJ, Henley JM Abstract The active regulation of spine structure and function is of fundamental importance for information storage in the brain. Many proteins involved in spine development and activity-dependent remodelling are potential or validated substrates for modification by the Small Ubiquitin-like Modifier (SUMO). The functional consequences of neuronal protein SUMOylation appear diverse and, in many cases, have not yet been determined. However, for several proteins SUMOylation has been shown to be a key regulator, which has a profound impact on spine dynamics and protein trafficking and function. Here we provide an overview of neuronal SUMOylation and discuss how greater understanding of this relatively recently discovered posttranslational modification will ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383867 Thu, 03 Nov 2011 04:00:00 +0100 5383867 http://www.medworm.com/index.php?rid=5383866&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22054924%26dopt%3DAbstract Authors: Ross SE Abstract Although pain and itch are distinct sensations, most noxious chemicals are not very specific to one sensation over the other, and recent discoveries are revealing that Trp channels function as transducers for both. A key difference between these sensations is that itch is initiated by irritation of the skin, whereas pain can be elicited from almost anywhere in the body; thus, itch may be encoded by the selective activation of specific subsets of neurons that are tuned to detect harmful stimuli at the surface and have specialized central connectivity that is specific to itch. Within the spinal cord, cross-modal inhibition between pain and itch may help sharpen the distinction between these sensations. Moreover, this idea that somatosensory modalities inhibi... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383866 Thu, 03 Nov 2011 04:00:00 +0100 5383866 http://www.medworm.com/index.php?rid=5383865&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22054925%26dopt%3DAbstract Authors: Daghfous G, Green WW, Zielinski BS, Dubuc R Abstract Chemical sensory signals play a crucial role in eliciting motor behaviors. We now review the different motor behaviors induced by chemosensory stimuli in fish as well as their neural substrate. A great deal of research has focused on migratory, reproductive, foraging, and escape behaviors but it is only recently that the molecules mediating these chemotactic responses have become well-characterized. Chemotactic responses are mediated by three sensory systems: olfactory, gustatory, and diffuse chemosensory. The olfactory sensory neuron responses to chemicals are now better understood. In addition, the olfactory projections to the central nervous system were recently shown to display an odotopic organization in the forebra... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383865 Thu, 03 Nov 2011 04:00:00 +0100 5383865 http://www.medworm.com/index.php?rid=5383868&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22054814%26dopt%3DAbstract Authors: Long MA, Lee AK Abstract Electrophysiological recordings from behaving animals provide an unparalleled view into the functional role of individual neurons. Intracellular approaches can be especially revealing as they provide information about a neuron's inputs and intrinsic cellular properties, which together determine its spiking output. Recent technical developments have made intracellular recording possible during an ever-increasing range of behaviors in both head-fixed and freely moving animals. These recordings have yielded fundamental insights into the cellular and circuit mechanisms underlying neural activity during natural behaviors in such areas as sensory perception, motor sequence generation, and spatial navigation, forging a direct link between cellular and sys... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383868 Wed, 02 Nov 2011 04:00:00 +0100 5383868 http://www.medworm.com/index.php?rid=5383880&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22051692%26dopt%3DAbstract Authors: Sigrist SJ, Sabatini BL Abstract Understanding the highly plastic nature of neurons requires the dynamic visualization of their molecular and cellular organization in a native context. However, due to the limited resolution of standard light microscopy, many of the structural specializations of neurons cannot be resolved. A recent revolution in light microscopy has given rise to several super-resolution light microscopy methods yielding 2-10-fold higher resolution than conventional microscopy. We here describe the principles behind these techniques as well as their application to the analysis of the molecular architecture of the synapse. Furthermore, we discuss the potential for continued development of super-resolution microscopy as necessary for live imaging of neuronal ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383880 Tue, 01 Nov 2011 04:00:00 +0100 5383880 http://www.medworm.com/index.php?rid=5383870&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22051693%26dopt%3DAbstract Authors: Hao J, Oertner TG Abstract Timing-dependent long-term potentiation (t-LTP) is induced when synaptic activity is immediately followed by one or more back-propagating action potentials (bAPs) in the postsynaptic cell. As a mechanistic explanation, it has been proposed that the bAP removes the Mg(2+) block of synaptic NMDA receptors, allowing for rapid Ca(2+) entry at the active synapse. Recent experimental studies suggest that this model is incomplete: NMDA receptor-based coincidence detection requires strong postsynaptic depolarization, usually provided by AMPA receptor currents. Apparently, the brief AMPA-EPSP does not only enable t-LTP, it is also responsible for the very narrow time window for t-LTP induction. The emerging consensus puts the spine in the center of coinci... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383870 Tue, 01 Nov 2011 04:00:00 +0100 5383870 http://www.medworm.com/index.php?rid=5383869&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22051694%26dopt%3DAbstract Authors: Opazo P, Sainlos M, Choquet D Abstract Excitatory synaptic transmission is largely mediated by AMPA receptors (AMPARs) present at the postsynaptic density. Recent studies in single molecule tracking of AMPAR has revealed that extrasynaptic AMPARs are highly mobile and thus might serve as a readily available pool for their synaptic recruitment during synaptic plasticity events such as long-term potentiation (LTP). Because this hypothesis relies on the cell's ability to increase the number of diffusional traps or 'slots' at synapses during LTP, we will review a number of protein-protein interactions that might impact AMPARs lateral diffusion and thus potentially serve as slots. Recent studies have identified the interaction between the AMPAR-Stargazin complex and PSD-95 as t... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383869 Tue, 01 Nov 2011 04:00:00 +0100 5383869 http://www.medworm.com/index.php?rid=5383891&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22048001%26dopt%3DAbstract Authors: Imai Y, Lu B Abstract Parkinson's disease (PD), the most common movement disorder, is characterized by age-dependent degeneration of dopaminergic neurons in the substantia nigra of the mid-brain. Non-motor symptoms of PD, however, precede the motor features caused by dysfunction of the dopaminergic system, suggesting that PD is a systemic disorder. Mitochondrial dysfunction has long been observed in PD patients and animal models, but the mechanistic link between mitochondrial dysfunction and PD pathogenesis is not well understood. Recent studies have revealed that genes associated with autosomal recessive forms of PD such as PINK1 and Parkin are directly involved in regulating mitochondrial morphology and maintenance, abnormality of which is also observed in the more commo... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383891 Mon, 31 Oct 2011 04:00:00 +0100 5383891 http://www.medworm.com/index.php?rid=5383903&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22036768%26dopt%3DAbstract Authors: Yan D, Noma K, Jin Y Abstract The unique ability of chemical synapses to transmit information relies on the structural organization of presynaptic terminals. Empowered by forward genetics, research using Caenorhabditis elegans has continued to make pivotal contributions to discover conserved regulators and pathways for presynaptic development. Recent advances in microscopy have begun to pave the path for linking molecular dynamics with subsynaptic structures. Studies using diverse reporters for synapses further broaden the landscape of regulatory mechanisms underlying presynaptic differentiation. The identification of novel regulators at transcriptional and post-transcriptional levels raises new questions for understanding synapse formation at the genomic scale. PMID: ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383903 Fri, 28 Oct 2011 04:00:00 +0100 5383903 http://www.medworm.com/index.php?rid=5383897&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22036769%26dopt%3DAbstract Authors: Hines RM, Davies PA, Moss SJ, Maguire J Abstract Inhibitory neurotransmission is primarily governed by γ-aminobutyric acid (GABA) type A receptors (GABA(A)Rs). GABA(A)Rs are heteropentameric ligand-gated channels formed by the combination of 19 possible subunits. GABA(A)R subunits are subject to multiple types of regulation, impacting the localization, properties, and function of assembled receptors. GABA(A)Rs mediate both phasic (synaptic) and tonic (extrasynaptic) inhibition. While the regulatory mechanisms governing synaptic receptors have begun to be defined, little is known about the regulation of extrasynaptic receptors. We examine the contributions of GABA(A)Rs to the pathogenesis of neurodevelopmental disorders, schizophrenia, depression, epilepsy, and stroke, wit... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383897 Fri, 28 Oct 2011 04:00:00 +0100 5383897 http://www.medworm.com/index.php?rid=5383919&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22036016%26dopt%3DAbstract Authors: Chung WS, Barres BA Abstract Excessive synapses generated during early development are eliminated extensively to form functionally mature neural circuits. Synapses in juvenile and mature brains are highly dynamic, and undergo remodeling processes through constant formation and elimination of dendritic spines. Although neural activity has been implicated in initiating the synapse elimination process cell-autonomously, the cellular and molecular mechanisms that transduce changes in correlated neural activity into structural changes in synapses are largely unknown. Recently, however, new findings provide evidence that in different species, glial cells, non-neuronal cell types in the nervous system are crucial in eliminating neural debris and unwanted synapses through phagocyt... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383919 Thu, 27 Oct 2011 04:00:00 +0100 5383919 http://www.medworm.com/index.php?rid=5383920&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22033281%26dopt%3DAbstract Authors: Nusser Z Abstract Following the astonishing molecular diversity of voltage-gated ion channels that was revealed in the past few decades, the ion channel repertoire expressed by neurons has been implicated as the major factor governing their functional heterogeneity. Although the molecular structure of ion channels is a key determinant of their biophysical properties, their subcellular distribution and densities on the surface of nerve cells are just as important for fulfilling functional requirements. Recent results obtained with high resolution quantitative localization techniques revealed complex, subcellular compartment-specific distribution patterns of distinct ion channels. Here I suggest that within a given neuron type every ion channel has a unique cell surface dist... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383920 Tue, 25 Oct 2011 04:00:00 +0100 5383920 http://www.medworm.com/index.php?rid=5383922&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22030345%26dopt%3DAbstract Authors: Jefferis GS, Livet J Abstract Sparse, random labelling of individual cells is a key approach to study brain circuit organisation and development. An array of methods based on genetic engineering now complements older methods such as Golgi staining, facilitating analysis while providing higher information content. Increasingly refined expression strategies based on transcriptional modulators and site-specific recombinases are used to distribute markers or combinations of markers within specific neuronal subsets. Several trends are emerging: first, increasing labelling density with multiplexed markers to allow more cells to be reliably distinguished; second, using labels to report lineage relationships among defined cells in addition to anatomy; third, coupling cell labellin... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383922 Mon, 24 Oct 2011 04:00:00 +0100 5383922 http://www.medworm.com/index.php?rid=5383921&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22030346%26dopt%3DAbstract Authors: Gundelfinger ED, Fejtova A Abstract Regulated neurotransmitter release from presynaptic boutons is crucial for the functioning of chemical synapses, what in turn governs the functional performance of the nervous system. Release occurs at the active zone (AZ), a specialized region of the presynaptic plasma membrane that is defined by a unique and complex meshwork of proteins-the cytomatrix at the AZ (CAZ). Important functions of CAZ proteins include recruitment, docking and priming of synaptic vesicles as well as appropriate localization of voltage-gated calcium channels near vesicle docking sites. We will discuss recent progress in the understanding of the topological localization and the molecular functions of characteristic CAZ proteins as well as emerging molecular mech... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383921 Mon, 24 Oct 2011 04:00:00 +0100 5383921 http://www.medworm.com/index.php?rid=5383923&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22023727%26dopt%3DAbstract Authors: Einevoll GT, Franke F, Hagen E, Pouzat C, Harris KD Abstract The new generation of silicon-based multielectrodes comprising hundreds or more electrode contacts offers unprecedented possibilities for simultaneous recordings of spike trains from thousands of neurons. Such data will not only be invaluable for finding out how neural networks in the brain work, but will likely be important also for neural prosthesis applications. This opportunity can only be realized if efficient, accurate and validated methods for automatic spike sorting are provided. In this review we describe some of the challenges that must be met to achieve this goal, and in particular argue for the critical need of realistic model data to be used as ground truth in the validation of spike-sorting algorith... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383923 Sat, 22 Oct 2011 04:00:00 +0100 5383923 http://www.medworm.com/index.php?rid=5383924&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22019151%26dopt%3DAbstract Authors: Benson DL, Huntley GW Abstract Cell adhesion molecules (CAMs) linked to cytoskeleton generate stable cell-cell junctions. Cadherins provide a canonical example, but paradoxically, they participate in a multitude of transient and regulatable interactions. Their extracellular binding generates weak adhesion that is modified by clustering; interactions with F-actin are regulated, can be transient, and can alter F-actin dynamics. Additionally, cadherin recycling from the cell surface can modify the size and location of junctions and strength of adhesion. In epithelial cells, this ongoing dynamic behavior is important for maintaining stable junctions. Recent work supports that cadherins act similarly at synapses where their actions are likely to be shared by integrins and other... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383924 Fri, 21 Oct 2011 04:00:00 +0100 5383924 http://www.medworm.com/index.php?rid=5383925&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22000952%26dopt%3DAbstract Authors: Lu W, Roche KW Abstract In the mammalian central nervous system, the majority of fast excitatory synaptic transmission is mediated by glutamate acting on AMPA-type ionotropic glutamate receptors. The abundance of AMPA receptors at the synapse can be modulated through receptor trafficking, which dynamically regulates many fundamental brain functions, including learning and memory. Reversible posttranslational modifications, including phosphorylation, palmitoylation and ubiquitination of AMPA receptor subunits are important regulatory mechanisms for controlling synaptic AMPA receptor expression and function. In this review, we highlight recent advances in the study of AMPA receptor posttranslational modifications and discuss how these modifications regulate AMPA receptor tra... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383925 Fri, 14 Oct 2011 04:00:00 +0100 5383925 http://www.medworm.com/index.php?rid=5383926&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22000839%26dopt%3DAbstract Authors: Verpelli C, Sala C Abstract The search for genetic causes of intellectual disability has identified, over the past twenty years, numerous mutated genes that code for proteins concerned with synapse function. Functional studies have shown that these genes may be involved in synapse formation, the synthesis and degradation of specific synapse proteins, the regulation of dendritic spine morphology, or regulation of the synaptic cytoskeleton. It is now clear that even mild alterations in synapse morphology and function can give rise to intellectual disability, and pharmacological agents able to counteract these morphological and functional anomalies - and improve the symptoms of some of these conditions - now appear feasible. This paper reviews recent findings on the functions... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383926 Thu, 13 Oct 2011 04:00:00 +0100 5383926 http://www.medworm.com/index.php?rid=5383927&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22000687%26dopt%3DAbstract Authors: Grueter BA, Rothwell PE, Malenka RC Abstract Exposure to addictive drugs causes changes in synaptic function within the striatal complex, which can either mimic or interfere with the induction of synaptic plasticity. These synaptic adaptations include changes in the nucleus accumbens (NAc), a ventral striatal subregion important for drug reward and reinforcement, as well as the dorsal striatum, which may promote habitual drug use. As the behavioral effects of drugs of abuse are long-lasting, identifying persistent changes in striatal circuits induced by in vivo drug experience is of considerable importance. Within the striatum, drugs of abuse have been shown to induce modifications in dendritic morphology, ionotropic glutamate receptors (iGluR) and the induction of synapti... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5383927 Wed, 12 Oct 2011 04:00:00 +0100 5383927 http://www.medworm.com/index.php?rid=5319397&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21993243%26dopt%3DAbstract Authors: Straub C, Tomita S Abstract At excitatory synapses in the brain, glutamate released from nerve terminals binds to glutamate receptors to mediate signaling between neurons. Glutamate receptors expressed in heterologous cells show ion channel activity. Recently, native glutamate receptors were shown to contain auxiliary subunits that modulate the trafficking and/or channel properties. The AMPA receptor (AMPAR) can contain TARP and CNIHs as the auxiliary subunits, whereas kainate receptor (KAR) can contain the Neto auxiliary subunit. Each of these auxiliary subunits uniquely modulates the glutamate receptors, and determines properties of native glutamate receptors. A thorough elucidation of the properties of native glutamate receptor complexes is indispensable for the underst... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5319397 Mon, 10 Oct 2011 04:00:00 +0100 5319397 http://www.medworm.com/index.php?rid=5319398&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21983330%26dopt%3DAbstract Authors: Vitureira N, Letellier M, Goda Y Abstract Homeostatic synaptic plasticity remains an enigmatic form of synaptic plasticity. Increasing interest on the topic has fuelled a surge of recent studies that have identified key molecular players and the signaling pathways involved. However, the new findings also highlight our lack of knowledge concerning some of the basic properties of homeostatic synaptic plasticity. In this review we address how homeostatic mechanisms balance synaptic strengths between the presynaptic and the postsynaptic terminals and across synapses that share the same postsynaptic neuron. PMID: 21983330 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5319398 Fri, 07 Oct 2011 04:00:00 +0100 5319398 http://www.medworm.com/index.php?rid=5319399&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21981809%26dopt%3DAbstract Authors: Berthoud HR Abstract Obesity is on the rise in all developed countries, and a large part of this epidemic has been attributed to excess caloric intake, induced by ever present food cues and the easy availability of energy dense foods in an environment of plenty. Clearly, there are strong homeostatic regulatory mechanisms keeping body weight of many individuals exposed to this environment remarkably stable over their adult life. Other individuals, however, seem to eat not only because of metabolic need, but also because of excessive hedonic drive to make them feel better and relieve stress. In the extreme, some individuals exhibit addiction-like behavior toward food, and parallels have been drawn to drug and alcohol addiction. However, there is an important distinction in t... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5319399 Wed, 05 Oct 2011 04:00:00 +0100 5319399 http://www.medworm.com/index.php?rid=5284637&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963829%26dopt%3DAbstract Authors: Kornum BR, Faraco J, Mignot E Abstract The loss of hypothalamic hypocretin/orexin (hcrt) producing neurons causes narcolepsy with cataplexy. An autoimmune basis for the disease has long been suspected and recent results have greatly strengthened this hypothesis. Narcolepsy with hcrt deficiency is now known to be associated with a Human Leukocyte Antigen (HLA) and T-cell receptor (TCR) polymorphisms, suggesting that an autoimmune process targets a single peptide unique to hcrt-cells via specific HLA-peptide-TCR interactions. Recent data have shown a robust seasonality of disease onset in children and associations with Streptococcus Pyogenes, and influenza A H1N1-infection and H1N1-vaccination, pointing towards processes such as molecular mimicry or bystander activation as c... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5284637 Fri, 30 Sep 2011 04:00:00 +0100 5284637 http://www.medworm.com/index.php?rid=5284639&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21962484%26dopt%3DAbstract Authors: Malinow R Abstract Since the initial findings that NMDA receptors play important roles in cellular models of learning as well as neurotoxicity, abnormal function of this receptor has been considered a potential mechanism in the pathophysiology underlying Alzheimer's disease. Treatment of Alzheimer's disease with an NMDA receptor antagonist began several years ago, with some limited success. More recent mechanistic studies have examined the role of NMDA receptors in the synaptic effects of beta amyloid (Aβ). PMID: 21962484 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5284639 Thu, 29 Sep 2011 04:00:00 +0100 5284639 http://www.medworm.com/index.php?rid=5284638&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963169%26dopt%3DAbstract Authors: Bosch M, Hayashi Y Abstract Dendritic spines are small mushroom-like protrusions arising from neurons where most excitatory synapses reside. Their peculiar shape suggests that spines can serve as an autonomous postsynaptic compartment that isolates chemical and electrical signaling. How neuronal activity modifies the morphology of the spine and how these modifications affect synaptic transmission and plasticity are intriguing issues. Indeed, the induction of long-term potentiation (LTP) or depression (LTD) is associated with the enlargement or shrinkage of the spine, respectively. This structural plasticity is mainly controlled by actin filaments, the principal cytoskeletal component of the spine. Here we review the pioneering microscopic studies examining the structural p... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5284638 Wed, 28 Sep 2011 04:00:00 +0100 5284638 http://www.medworm.com/index.php?rid=5268967&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21944260%26dopt%3DAbstract Authors: Micheva KD, Bruchez MP Abstract The rapid accumulation of neuroproteomics data in recent years has prompted the emergence of novel antibody-based imaging methods that aim to understand the anatomical and functional context of the multitude of identified proteins. The pioneering field of ultrastructural multiplexed proteomic imaging now includes a number of high resolution methods, such as array tomography, stimulated emission depletion microscopy, stochastic optical reconstruction microscopy and automated transmission electron microscopy, which allow a detailed molecular characterization of individual synapses and subsynaptic structures within brain tissues for the first time. While all of these methods still face considerable limitations, a combined complementary approach... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5268967 Wed, 21 Sep 2011 04:00:00 +0100 5268967 http://www.medworm.com/index.php?rid=5235824&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21925871%26dopt%3DAbstract Authors: Keller PJ, Dodt HU Abstract Light sheet microscopy is a versatile imaging technique with a unique combination of capabilities. It provides high imaging speed, high signal-to-noise ratio and low levels of photobleaching and phototoxic effects. These properties are crucial in a wide range of applications in the life sciences, from live imaging of fast dynamic processes in single cells to long-term observation of developmental dynamics in entire large organisms. When combined with tissue clearing methods, light sheet microscopy furthermore allows rapid imaging of large specimens with excellent coverage and high spatial resolution. Even samples up to the size of entire mammalian brains can be efficiently recorded and quantitatively analyzed. Here, we provide an overview of the... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5235824 Fri, 16 Sep 2011 04:00:00 +0100 5235824 http://www.medworm.com/index.php?rid=5222095&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21908183%26dopt%3DAbstract Authors: Behrens TE, Sporns O Abstract Recent advances in non-invasive neuroimaging have enabled the measurement of connections between distant regions in the living human brain, thus opening up a new field of research: Human connectomics. Different imaging modalities allow the mapping of structural connections (axonal fibre tracts) as well as functional connections (correlations in time series), and individual variations in these connections may be related to individual variations in behaviour and cognition. Connectivity analysis has already led to a number of new insights about brain organization. For example, segregated brain regions may be identified by their unique patterns of connectivity, structural and functional connectivity may be compared to elucidate how dynamic interac... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5222095 Fri, 09 Sep 2011 04:00:00 +0100 5222095 http://www.medworm.com/index.php?rid=5222101&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21907569%26dopt%3DAbstract Authors: Keene CD, Cudaback E, Li X, Montine KS, Montine TJ Abstract The largest genetic risk for late-onset Alzheimer's disease (AD) resides at the apolipoprotein E gene (APOE) locus, which has three common alleles (ɛ2, ɛ3, ɛ4) that encode three isoforms (apoE2, apoE3, apoE4). The very strong association of the APOE ɛ4 allele with AD risk and its role in the accumulation of amyloid β in brains of people and animal models solidify the biological relevance of apoE isoforms but do not provide mechanistic insight. The innate immune response is consistently observed in AD and is a likely contributor to neuronal injury and response to injury. Here we review emerging data showing that apoE isoform regulation of multiple facets of the innate immune response in the brain may alter AD ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5222101 Thu, 08 Sep 2011 04:00:00 +0100 5222101 http://www.medworm.com/index.php?rid=5222102&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21906931%26dopt%3DAbstract Authors: Wilson RI, du Lac S PMID: 21906931 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5222102 Wed, 07 Sep 2011 04:00:00 +0100 5222102 http://www.medworm.com/index.php?rid=5180578&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21873046%26dopt%3DAbstract Authors: Zhaoping L Abstract Some cortical circuit models study the mechanisms of the transforms from visual inputs to neural responses. They model neural properties such as feature tunings, pattern sensitivities, and how they depend on intracortical connections and contextual inputs. Other cortical circuit models are more concerned with computational goals of the transform from visual inputs to neural responses, or the roles of the neural responses in the visual behavior. The appropriate complexity of a cortical circuit model depends on the question asked. Modeling neural circuits of many interacting hypercolumns is a necessary challenge, which is providing insights to cortical computations, such as visual saliency computation, and linking physiology with global visual cognitive b... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5180578 Thu, 25 Aug 2011 23:00:00 +0100 5180578 http://www.medworm.com/index.php?rid=5161853&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21855320%26dopt%3DAbstract Authors: Lee WC, Reid RC Abstract A fundamental but unsolved problem in neuroscience is how connections between neurons might underlie information processing in central circuits. Building wiring diagrams of neural networks may accelerate our understanding of how they compute. But even if we had wiring diagrams, it is critical to know what neurons in a circuit are doing: their physiology. In both the retina and cerebral cortex, a great deal is known about topographic specificity, such as lamination and cell-type specificity of connections. Little, however, is known about connections as they relate to function. Here, we review how advances in functional imaging and electron microscopy have recently allowed the examination of relationships between sensory physiology and synaptic conne... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5161853 Wed, 17 Aug 2011 23:00:00 +0100 5161853 http://www.medworm.com/index.php?rid=5161852&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21856148%26dopt%3DAbstract Authors: Dayan P, Feller M, Feldman D PMID: 21856148 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5161852 Tue, 16 Aug 2011 23:00:00 +0100 5161852 http://www.medworm.com/index.php?rid=5119127&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21821411%26dopt%3DAbstract We describe the apparent mismatch between the number of cone bipolar cell types, and the diversity of excitatory input to retinal ganglion cells, and outline two possible solutions. One proposal is for diversity in the excitatory pathways to be generated within axon terminals of cone bipolar cells, and the second invokes narrow-field glycinergic amacrine cells that can apparently act like bipolar cells by providing excitatory drive to ganglion cells. Finally we highlight two advances in technique that promise to provide future insights; automation of electron microscope data collection and analysis, and the use of the ideal observer to quantitatively compare neural performance at all levels. PMID: 21821411 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5119127 Thu, 04 Aug 2011 23:00:00 +0100 5119127 http://www.medworm.com/index.php?rid=5119128&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21820895%26dopt%3DAbstract Authors: Burgess N, O'Keefe J Neuronal firing in the hippocampal formation (HF) of freely moving rodents shows striking examples of spatialorganization in the form of place, directional, boundary vector and grid cells. The firing of place and grid cells shows an intriguing form of temporal organization known as 'theta phase precession'. We review the mechanisms underlying theta phase precession of place cell firing, ranging from membrane potential oscillations to recurrent connectivity, and the relevant intra-cellular and extra-cellular data. We then consider the use of these models to explain the spatial structure of grid cell firing, and review the relevant intra-cellular and extra-cellular data. Finally, we consider the likely interaction between place cells, grid cells and boundary... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5119128 Wed, 03 Aug 2011 23:00:00 +0100 5119128 http://www.medworm.com/index.php?rid=5119129&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21813273%26dopt%3DAbstract Authors: Da Cruz S, Cleveland DW Dominant mutations in two DNA/RNA binding proteins, TDP-43 and FUS/TLS, are causes of inherited Amyotrophic Lateral Sclerosis (ALS). TDP-43 and FUS/TLS have striking structural and functional similarities, implicating alterations in RNA processing as central in ALS. TDP-43 has binding sites within a third of all mouse and human mRNAs in brain and this binding influences the levels and splicing patterns of at least 20% of those mRNAs. Disease modeling in rodents of the first known cause of inherited ALS-mutation in the ubiquitously expressed superoxide dismutase (SOD1)-has yielded non-cell autonomous fatal motor neuron disease caused by one or more toxic properties acquired by the mutant proteins. In contrast, initial disease modeling for TDP-43 and FUS/... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5119129 Sun, 31 Jul 2011 23:00:00 +0100 5119129 http://www.medworm.com/index.php?rid=5071209&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21782415%26dopt%3DAbstract Authors: Noam Y, Bernard C, Baram TZ Epilepsy is the third most common brain disorder and affects millions of people. Epilepsy is characterized by the occurrence of spontaneous seizures, that is, bursts of synchronous firing of large populations of neurons. These are believed to result from abnormal regulation of neuronal excitability that favors hypersynchrony. Among the intrinsic conductances that govern neuronal excitability, the hyperpolarization-activated current (I(h)) plays complex and important roles in the fine-tuning of both cellular and network activity. Not surprisingly, dysregulation of I(h) and/or of its conducting ion-channels (HCN) has been strongly implicated in various experimental models of epilepsy, as well as in human epilepsy. Here we provide an overview of recent... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5071209 Tue, 19 Jul 2011 23:00:00 +0100 5071209 http://www.medworm.com/index.php?rid=5071210&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21767944%26dopt%3DAbstract Authors: Carey MR The cerebellum plays an essential role in motor learning. The ability to identify specific sensory and motor signals carried by neurons with known connectivity makes the cerebellum an attractive system for investigating how synaptic plasticity relates to learning. Early studies focused primarily on a single form of plasticity, long-term depression at parallel fiber-Purkinje cell synapses. Recent work has highlighted both the diversity of synaptic plasticity that exists within the cerebellum and the fact that individual plasticity mechanisms can have unexpected consequences when they act within neural circuits. PMID: 21767944 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5071210 Fri, 15 Jul 2011 23:00:00 +0100 5071210 http://www.medworm.com/index.php?rid=5071212&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21764294%26dopt%3DAbstract Authors: Krakauer JW, Mazzoni P Recent studies of upper limb movements have provided insights into the computations, mechanisms, and taxonomy of human sensorimotor learning. Motor tasks differ with respect to how they weight different learning processes. These include adaptation, an internal-model based process that reduces sensory-prediction errors in order to return performance to pre-perturbation levels, use-dependent plasticity, and operant reinforcement. Visuomotor rotation and force-field tasks impose systematic errors and thereby emphasize adaptation. In skill learning tasks, which for the most part do not involve a perturbation, improved performance is manifest as reduced motor variability and probably depends less on adaptation and more on success-based exploration. Explicit a... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5071212 Thu, 14 Jul 2011 23:00:00 +0100 5071212 http://www.medworm.com/index.php?rid=5071211&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21764577%26dopt%3DAbstract Authors: Lockery SR Spatial orientation behaviors in animals are fundamental for survival but poorly understood at the neuronal level. The nematode Caenorhabditis elegans orients to a wide range of stimuli and has a numerically small and well-described nervous system making it advantageous for investigating the mechanisms of spatial orientation. Recent work by the C. elegans research community has identified essential computational elements of the neural circuits underlying two orientation strategies that operate in five different sensory modalities. Analysis of these circuits reveals novel motifs including simple circuits for computing temporal derivatives of sensory input and for integrating sensory input with behavioral state to generate adaptive behavior. These motifs constitute hy... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5071211 Wed, 13 Jul 2011 23:00:00 +0100 5071211 http://www.medworm.com/index.php?rid=5071213&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21763124%26dopt%3DAbstract Authors: Fee MS, Long MA Where are the 'prime movers' that control behavior? Which circuits in the brain control the order in which individual motor gestures of a learned behavior are generated, and the speed at which they progress? Here we describe two techniques recently applied to localizing and characterizing the circuitry underlying the generation of vocal sequences in the songbird. The first utilizes small, localized, temperature changes in the brain to perturb the speed of neural dynamics. The second utilizes intracellular manipulation of membrane potential in the freely behaving animal to perturb the dynamics within a single neuron. Both of these techniques are broadly applicable in behaving animals to test hypotheses about the biophysical and circuit dynamics that allow neural... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5071213 Tue, 12 Jul 2011 23:00:00 +0100 5071213 http://www.medworm.com/index.php?rid=5071214&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21752634%26dopt%3DAbstract Authors: Wang X, Sommer FT, Hirsch JA Synapses made by local interneurons dominate the intrinsic circuitry of the mammalian visual thalamus and influence all signals traveling from the eye to cortex. Here we draw on physiological and computational analyses of receptive fields in the cat's lateral geniculate nucleus to describe how inhibition helps to enhance selectivity for stimulus features in space and time and to improve the efficiency of the neural code. Further, we explore specialized synaptic attributes of relay cells and interneurons and discuss how these might be adapted to preserve the temporal precision of retinal spike trains and thereby maximize the rate of information transmitted downstream. PMID: 21752634 [PubMed - as supplied by publisher] (Source: Current Opinion in... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5071214 Sun, 10 Jul 2011 23:00:00 +0100 5071214 http://www.medworm.com/index.php?rid=5024929&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21742484%26dopt%3DAbstract Authors: Lochmann T, Deneve S Perception is about making sense, that is, understanding what events in the outside world caused the sensory observations. Consistent with this intuition, many aspects of human behavior confronting noise and ambiguity are well explained by principles of causal inference. Extending these insights, recent studies have applied the same powerful set of tools to perceptual processing at the neural level. According to these approaches, microscopic neural structures solve elementary probabilistic tasks and can be combined to construct hierarchical predictive models of the sensory input. This framework suggests that variability in neural responses reflects the inherent uncertainty associated with sensory interpretations and that sensory neurons are active predicto... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024929 Thu, 07 Jul 2011 23:00:00 +0100 5024929 http://www.medworm.com/index.php?rid=5024930&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21737252%26dopt%3DAbstract Authors: Menet JS, Rosbash M Patients suffering from neuropsychiatric disorders often exhibit a loss of regulation of their biological rhythms which leads to altered sleep/wake cycle, body temperature rhythm and hormonal rhythms. Whereas these symptoms have long been considered to result from the pathology of the underlying disease, increasing evidence now indicates that the circadian system may be more directly involved in the etiology of psychiatric disorders. This emerging view originated with the discovery that the genes involved in the generation of biological rhythms are expressed in many brain structures where clocks function-and perhaps malfunction. It is also due to the interesting phenotypes of clock mutant mice. Here we summarize recent reports showing that alteration of cir... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024930 Mon, 04 Jul 2011 23:00:00 +0100 5024930 http://www.medworm.com/index.php?rid=5024932&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21733672%26dopt%3DAbstract Authors: Shepherd GM, Katz DM Recent findings in the genetics of neurodevelopmental syndromes have ushered in an exciting era of discovery in which substrates of neurologic dysfunction are being identified at the synaptic and microcircuit levels in mouse models of these disorders. We review recent progress in this area, focusing on two examples of mouse models of autism spectrum disorders (ASDs): Mecp2 models of Rett syndrome, and a Met-knockout model of non-syndromic forms of autism. In both cases, a dominant theme is changes in synaptic strength, associated with hyper-connectivity or hypo-connectivity in specific microcircuits. Alterations in intrinsic neuronal excitability are also found, but do not appear to be as common. The microcircuit-specific nature of synaptic changes observe... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024932 Sun, 03 Jul 2011 23:00:00 +0100 5024932 http://www.medworm.com/index.php?rid=5024931&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21733673%26dopt%3DAbstract Authors: Bastian AJ The cerebellum is a subcortical brain structure that is essential for learning and controlling movement. Recent work shows that the cerebellum also plays a role in certain perceptual abilities, beyond what would be expected secondary to poor movement control. This review covers these and other recent advances, focusing on how cerebellar damage affects human abilities ranging from sensory perception to movement control and motor learning. PMID: 21733673 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024931 Sun, 03 Jul 2011 23:00:00 +0100 5024931 http://www.medworm.com/index.php?rid=5024933&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21724382%26dopt%3DAbstract Authors: Graybiel AM, Morris R PMID: 21724382 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024933 Fri, 01 Jul 2011 23:00:00 +0100 5024933 http://www.medworm.com/index.php?rid=5024934&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21723114%26dopt%3DAbstract Authors: Bruno RM How neurons encode information has been a hotly debated issue. Ultimately, any code must be relevant to the senders, receivers, and connections between them. This review focuses on the transmission of sensory information through the circuit linking thalamus and cortex, two distant brain regions. Strong feedforward inhibition in the thalamocortical circuit renders cortex highly sensitive to the thalamic synchrony evoked by a sensory stimulus. Neuromodulators and feedback connections may modulate the temporal sensitivity of such circuits and gate the propagation of synchrony into other layers and cortical areas. The prevalence of strong feedforward inhibitory circuits throughout the central nervous system suggests that synchrony codes and timing-sensitive circuits may b... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024934 Tue, 28 Jun 2011 23:00:00 +0100 5024934 http://www.medworm.com/index.php?rid=5024935&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21715156%26dopt%3DAbstract Authors: Destexhe A The mammalian cerebral cortex is characterized by intense spontaneous activity, depending on brain region, age, and behavioral state. Classically, the cortex is considered as being driven by the senses, a paradigm which corresponds well to experiments in quiescent or deeply anesthetized states. In awake animals, however, the spontaneous activity cannot be considered as 'background noise', but is of comparable-or even higher-amplitude than evoked sensory responses. Recent evidence suggests that this internal activity is not only dominant, but also it shares many properties with the responses to natural sensory inputs, suggesting that the spontaneous activity is not independent of the sensory input. Such evidence is reviewed here, with an emphasis on intracellular and... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024935 Sun, 26 Jun 2011 23:00:00 +0100 5024935 http://www.medworm.com/index.php?rid=5024936&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21708457%26dopt%3DAbstract Authors: Busskamp V, Roska B Retinitis pigmentosa is a hereditary eye disease that affects photoreceptors and leads to blindness. The discovery of a microbial light-gated channel and the subsequent development of similar 'optogenetic' sensors have opened the door to creating artificial photoreceptors in the remaining retinal circuits of retinitis pigmentosa retinas via gene therapy. Here we review recent studies in animal models of retinitis pigmentosa that have combined knowledge of retinal cell types, circuits and computations with the ability to equip cell types with optogenetic sensors in order to restore visual activity. We also discuss the translational potential of this therapy. PMID: 21708457 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=5024936 Fri, 24 Jun 2011 23:00:00 +0100 5024936 http://www.medworm.com/index.php?rid=4976269&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21705212%26dopt%3DAbstract Authors: Huston SJ, Jayaraman V Sensorimotor integration is a field rich in theory backed by a large body of psychophysical evidence. Relating the underlying neural circuitry to these theories has, however, been more challenging. With a wide array of complex behaviors coordinated by their small brains, insects provide powerful model systems to study key features of sensorimotor integration at a mechanistic level. Insect neural circuits perform both hard-wired and learned sensorimotor transformations. They modulate their neural processing based on both internal variables, such as the animal's behavioral state, and external ones, such as the time of day. Here we present some studies using insect model systems that have produced insights, at the level of individual neurons, about sensorim... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976269 Thu, 23 Jun 2011 23:00:00 +0100 4976269 http://www.medworm.com/index.php?rid=4976268&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21705213%26dopt%3DAbstract Authors: Moss CF, Chiu C, Surlykke A Echolocation operates through adaptive sensorimotor systems that collectively enable the bat to localize and track sonar objects as it flies. The features of sonar signals used by a bat to probe its surroundings determine the information available to its acoustic imaging system. In turn, the bat's perception of a complex scene guides its active adjustments in the features of subsequent sonar vocalizations. Here, we propose that the bat's active vocal-motor behaviors play directly into its representation of a dynamic auditory scene. PMID: 21705213 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976268 Thu, 23 Jun 2011 23:00:00 +0100 4976268 http://www.medworm.com/index.php?rid=4976271&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704507%26dopt%3DAbstract Authors: Requarth T, Sawtell NB This review focuses on recent progress in understanding mechanisms for filtering self-generated sensory signals in cerebellum-like circuits in fish and mammals. Recent in vitro studies in weakly electric gymnotid fish have explored the interplay among anti-Hebbian plasticity, synaptic dynamics, and feedforward inhibition in canceling self-generated electrosensory inputs. Studies of the mammalian dorsal cochlear nucleus have revealed multimodal integration and anti-Hebbian plasticity, suggesting that this circuit may adaptively filter incoming auditory information. In vivo studies in weakly electric mormryid fish suggest a key role for granule cell coding in sensory filtering. The clear links between synaptic plasticity and systems level sensory filtering... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976271 Wed, 22 Jun 2011 23:00:00 +0100 4976271 http://www.medworm.com/index.php?rid=4976270&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704508%26dopt%3DAbstract Authors: Sharpee TO, Atencio CA, Schreiner CE Understanding the neural mechanisms of invariant object recognition remains one of the major unsolved problems in neuroscience. A common solution that is thought to be employed by diverse sensory systems is to create hierarchical representations of increasing complexity and tolerance. However, in the mammalian auditory system many aspects of this hierarchical organization remain undiscovered, including the prominent classes of high-level representations (that would be analogous to face selectivity in the visual system or selectivity to bird's own song in the bird) and the dominant types of invariant transformations. Here we review the recent progress that begins to probe the hierarchy of auditory representations, and the computational appro... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976270 Wed, 22 Jun 2011 23:00:00 +0100 4976270 http://www.medworm.com/index.php?rid=4976273&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21696944%26dopt%3DAbstract Authors: Davare M, Kraskov A, Rothwell JC, Lemon RN Skilled grasp is a sensorimotor process requiring the brain to extract sensory cues from the environment to shape a motor command. Although a large body of literature has focused on which brain areas either integrate the visual object's properties or control the motor output, it is still unclear how grasp-related information is transferred from one area to another. Understanding interactions between brain areas is crucial for the study of visuomotor transformations. Recently, new advances in both human and non-human primates have shown it is possible to study cortico-cortical interactions during different task contexts. This sheds new light on how brain areas are integrated in a dynamic network for controlling grasping actions. PM... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976273 Sun, 19 Jun 2011 23:00:00 +0100 4976273 http://www.medworm.com/index.php?rid=4976272&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21696945%26dopt%3DAbstract Authors: Mysore SP, Knudsen EI A midbrain network interacts with the well-known frontoparietal forebrain network to select stimuli for gaze and spatial attention. The midbrain network, containing the superior colliculus (SC; optic tectum, OT, in non-mammalian vertebrates) and the isthmic nuclei, helps evaluate the relative priorities of competing stimuli and encodes them in a topographic map of space. Behavioral experiments in monkeys demonstrate an essential contribution of the SC to stimulus selection when the relative priorities of competing stimuli are similar. Neurophysiological results from the owl OT demonstrate a neural correlate of this essential contribution of the SC/OT. The multi-layered, spatiotopic organization of the midbrain network lends itself to the analysis and mode... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976272 Sun, 19 Jun 2011 23:00:00 +0100 4976272 http://www.medworm.com/index.php?rid=4976278&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21689922%26dopt%3DAbstract Authors: Osborne LC Performance in sensory-motor behaviors guides our understanding of many of the key computational functions of the brain: the representation of sensory information, the translation of sensory signals to commands for movement, and the production of behavior. Eye movement behaviors have become a valuable testing ground for theories of neural computation because the neural circuitry has been well characterized and the mechanical control of the eye is comparatively simple. Here I review recent studies of eye movement behaviors that provide insight into sensory-motor computation at the single neuron and systems levels. They show that errors in sensory estimation dominate eye movement variability and that the motor system functions to reduce the behavioral impact of its ow... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976278 Fri, 17 Jun 2011 23:00:00 +0100 4976278 http://www.medworm.com/index.php?rid=4976277&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21689923%26dopt%3DAbstract Authors: Orbán G, Wolpert DM Uncertainty is ubiquitous in our sensorimotor interactions, arising from factors such as sensory and motor noise and ambiguity about the environment. Setting it apart from previous theories, a quintessential property of the Bayesian framework for making inference about the state of world so as to select actions, is the requirement to represent the uncertainty associated with inferences in the form of probability distributions. In the context of sensorimotor control and learning, the Bayesian framework suggests that to respond optimally to environmental stimuli the central nervous system needs to construct estimates of the sensorimotor transformations, in the form of internal models, as well as represent the structure of the uncertainty in the inputs, outpu... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976277 Fri, 17 Jun 2011 23:00:00 +0100 4976277 http://www.medworm.com/index.php?rid=4976276&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21689924%26dopt%3DAbstract Authors: Cullen KE As we move through the world, information can be combined from multiple sources in order to allow us to perceive our self-motion. The vestibular system detects and encodes the motion of the head in space. In addition, extra-vestibular cues such as retinal-image motion (optic flow), proprioception, and motor efference signals, provide valuable motion cues. Here I focus on the coding strategies that are used by the brain to create neural representations of self-motion. I review recent studies comparing the thresholds of single versus populations of vestibular afferent and central neurons. I then consider recent advances in understanding the brain's strategy for combining information from the vestibular sensors with extra-vestibular cues to estimate self-motion. These s... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976276 Fri, 17 Jun 2011 23:00:00 +0100 4976276 http://www.medworm.com/index.php?rid=4976275&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21689925%26dopt%3DAbstract Authors: Srinivasan MV Flying insects display remarkable agility, despite their diminutive eyes and brains. This review describes our growing understanding of how these creatures use visual information to stabilize flight, avoid collisions with objects, regulate flight speed, detect and intercept other flying insects such as mates or prey, navigate to a distant food source, and orchestrate flawless landings. It also outlines the ways in which these insights are now being used to develop novel, biologically inspired strategies for the guidance of autonomous, airborne vehicles. PMID: 21689925 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976275 Fri, 17 Jun 2011 23:00:00 +0100 4976275 http://www.medworm.com/index.php?rid=4976274&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21689926%26dopt%3DAbstract Authors: Blitz DM, Nusbaum MP Neuronal circuits underlying rhythmic behaviors (central pattern generators: CPGs) can generate rhythmic motor output without sensory input. However, sensory input is pivotal for generating behaviorally relevant CPG output. Here we discuss recent work in the decapod crustacean stomatogastric nervous system (STNS) identifying cellular and synaptic mechanisms whereby sensory inputs select particular motor outputs from CPG circuits. This includes several examples in which sensory neurons regulate the impact of descending projection neurons on CPG circuits. This level of analysis is possible in the STNS due to the relatively unique access to identified circuit, projection, and sensory neurons. These studies are also revealing additional degrees of freedom in s... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976274 Fri, 17 Jun 2011 23:00:00 +0100 4976274 http://www.medworm.com/index.php?rid=4976280&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21684147%26dopt%3DAbstract Authors: Medina JF Neurophysiological recordings in the cerebellar cortex of awake-behaving animals are revolutionizing the way we think about the role of Purkinje cells in sensori-motor calibration. Early theorists suggested that if a movement became miscalibrated, Purkinje cell output would be changed to adjust the motor command and restore good performance. The finding that Purkinje cell activity changed in many sensori-motor calibration tasks was taken as strong support for this hypothesis. Based on more recent data, however, it has been suggested that changes in Purkinje cell activity do not contribute to the motor command directly; instead, they are used either as a teaching signal, or to predict the altered kinematics of the movement after calibration has taken place. I will arg... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976280 Wed, 15 Jun 2011 23:00:00 +0100 4976280 http://www.medworm.com/index.php?rid=4976279&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21684148%26dopt%3DAbstract Authors: Gjorgjieva J, Eglen SJ Spontaneous activity is found in many regions of the developing nervous system; such activity is thought to be instructive for guiding developmental processes. In particular, the developing retina generates correlated patterns of activity known as retinal waves. We review the main theoretical models that have been developed to study the mechanisms for generation and propagation of retinal waves. Much of the progress in this field has been due to the close interaction between experimentalists and theorists in analyzing and modeling spontaneous activity. We conclude by describing spontaneous activity models in other systems and suggestions for future modeling work. PMID: 21684148 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiol... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976279 Wed, 15 Jun 2011 23:00:00 +0100 4976279 http://www.medworm.com/index.php?rid=4976282&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21683574%26dopt%3DAbstract Authors: Chacron MJ, Longtin A, Maler L The electric sense combines spatial aspects of vision and touch with temporal features of audition. Its accessible neural architecture shares similarities with mammalian sensory systems and allows for recordings from successive brain areas to test hypotheses about neural coding. Further, electrosensory stimuli encountered during prey capture, navigation, and communication, can be readily synthesized in the laboratory. These features enable analyses of the neural circuitry that reveal general principles of encoding and decoding, such as segregation of information into separate streams and neural response sparsification. A systems level understanding arises via linkage between cellular differentiation and network architecture, revealed by in vitro ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976282 Tue, 14 Jun 2011 23:00:00 +0100 4976282 http://www.medworm.com/index.php?rid=4976281&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21683575%26dopt%3DAbstract Authors: Tytell E, Holmes P, Cohen A Neural circuits do not function in isolation; they interact with the physical world, accepting sensory inputs and producing outputs via muscles. Since both these pathways are constrained by physics, the activity of neural circuits can only be understood by considering biomechanics of muscles, bodies, and the exterior world. We discuss how animal bodies have natural stable motions that require relatively little activation or control from the nervous system. The nervous system can substantially alter these motions, by subtly changing mechanical properties such as body or leg stiffness. Mechanics can also provide robustness to perturbations without sensory reflexes. By considering a complete neuromechanical system, neuroscientists and biomechanicians t... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976281 Tue, 14 Jun 2011 23:00:00 +0100 4976281 http://www.medworm.com/index.php?rid=4976283&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21680173%26dopt%3DAbstract Authors: Lewis DA, Fish KN, Arion D, Gonzalez-Burgos G Deficits of cognitive control in schizophrenia are associated with altered gamma oscillations in the prefrontal cortex. Paralbumin basket interneurons, which innervate the perisomatic region of pyramidal neurons, appear to play a key role in generating cortical gamma oscillations. In the prefrontal cortex of subjects with schizophrenia, alterations are present in both pre- and post-synaptic markers of the strength of GABA inputs from parvalbumin basket neurons to pyramidal neurons. These alterations may contribute to the neural substrate for impaired gamma oscillations in schizophrenia. PMID: 21680173 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976283 Mon, 13 Jun 2011 23:00:00 +0100 4976283 http://www.medworm.com/index.php?rid=4976284&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21665461%26dopt%3DAbstract Authors: Kawato M, Kuroda S, Schweighofer N The biophysical models of spike-timing-dependent plasticity have explored dynamics with molecular basis for such computational concepts as coincidence detection, synaptic eligibility trace, and Hebbian learning. They overall support different learning algorithms in different brain areas, especially supervised learning in the cerebellum. Because a single spine is physically very small, chemical reactions at it are essentially stochastic, and thus sensitivity-longevity dilemma exists in the synaptic memory. Here, the cascade of excitable and bistable dynamics is proposed to overcome this difficulty. All kinds of learning algorithms in different brain regions confront with difficult generalization problems. For resolution of this issue, the cont... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4976284 Thu, 09 Jun 2011 23:00:00 +0100 4976284 http://www.medworm.com/index.php?rid=4926383&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21658933%26dopt%3DAbstract Authors: Shohamy D The past decade has seen a dramatic change in our understanding of the role of the striatum in behavior. Early perspectives emphasized a role for the striatum in habitual learning of stimulus-response associations and sequences of actions. Recent advances from human neuroimaging research suggest a broader role for the striatum in motivated learning. New findings demonstrate that the striatum represents multiple learning signals and highlight the contribution of the striatum across many cognitive domains and contexts. Recent findings also emphasize interactions between the striatum and other specialized brain systems for learning. Together, these findings suggest that the striatum contributes to a distributed network that learns to select actions based on their predic... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926383 Mon, 06 Jun 2011 23:00:00 +0100 4926383 http://www.medworm.com/index.php?rid=4926386&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21646012%26dopt%3DAbstract Authors: Ashida G, Carr CE Many animals use the interaural time differences (ITDs) to locate the source of low frequency sounds. The place coding theory proposed by Jeffress has long been a dominant model to account for the neural mechanisms of ITD detection. Recent research, however, suggests a wider range of strategies for ITD coding in the binaural auditory brainstem. We discuss how ITD is coded in avian, mammalian, and reptilian nervous systems, and review underlying synaptic and cellular properties that enable precise temporal computation. The latest advances in recording and analysis techniques provide powerful tools for both overcoming and utilizing the large field potentials in these nuclei. PMID: 21646012 [PubMed - as supplied by publisher] (Source: Current Opinion in Neur... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926386 Fri, 03 Jun 2011 23:00:00 +0100 4926386 http://www.medworm.com/index.php?rid=4926385&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21646013%26dopt%3DAbstract Authors: Harris-Warrick RM Central Pattern Generator (CPG) networks, which organize rhythmic movements, have long served as models for neural network organization. Modulatory inputs are essential components of CPG function: neuromodulators set the parameters of CPG neurons and synapses to render the networks functional. Each modulator acts on the network by many effects which may oppose one another; this may serve to stabilize the modulated state. Neuromodulators also determine the active neuronal composition in the CPG, which varies with state changes such as locomotor speed. The pattern of gene expression which determines the electrophysiological personality of each CPG neuron is also under modulatory control. It is not possible to model the function of neural networks without includ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926385 Fri, 03 Jun 2011 23:00:00 +0100 4926385 http://www.medworm.com/index.php?rid=4926384&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21646014%26dopt%3DAbstract Authors: Ibbotson M, Krekelberg B We use saccades several times per second to move the fovea between points of interest and build an understanding of our visual environment. Recent behavioral experiments show evidence for the integration of pre- and postsaccadic information (even subliminally), the modulation of visual sensitivity, and the rapid reallocation of attention. The recent physiological literature has identified a characteristic modulation of neural responsiveness-perisaccadic reduction followed by a postsaccadic increase-that is found in many visual areas, but whose source is as yet unknown. This modulation seems optimal for reducing sensitivity during and boosting sensitivity between saccades, but no study has yet established a direct causal link between neural and behavior... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926384 Fri, 03 Jun 2011 23:00:00 +0100 4926384 http://www.medworm.com/index.php?rid=4926388&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21641793%26dopt%3DAbstract Authors: Costa RM How are novel actions generated and learned? We introduce a selectionist view of de novo action learning, and present some of the main postulates of such a view. This view contrasts with the notion that all actions are generated in response to particular stimuli and hence instructed by the world. It postulates that actions are generated in the actor (the organism) and selected by the environment (stimuli). Selection may occur iteratively until actions can be executed more rapidly and precisely, less variably, and eventually be elicited by particular stimuli. We also discuss experiments that support the particular predictions of this theory. PMID: 21641793 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926388 Thu, 02 Jun 2011 23:00:00 +0100 4926388 http://www.medworm.com/index.php?rid=4926387&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21641794%26dopt%3DAbstract Authors: Azeredo da Silveira R, Roska B How does the connectivity of a neuronal circuit, together with the individual properties of the cell types that take part in it, result in a given computation? We examine this question in the context of retinal circuits. We suggest that the retina can be viewed as a parallel assemblage of many small computational devices, highly stereotypical and task-specific circuits afferent to a given ganglion cell type, and we discuss some rules that govern computation in these devices. Multi-device processing in retina poses conceptual problems when it is contrasted with cortical processing. We lay out open questions both on processing in retinal circuits and on implications for cortical processing of retinal inputs. PMID: 21641794 [PubMed - as supplied... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926387 Thu, 02 Jun 2011 23:00:00 +0100 4926387 http://www.medworm.com/index.php?rid=4926389&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21636266%26dopt%3DAbstract Authors: Kullmann DM The hippocampus has contributed enormously to our understanding of the operation of elemental brain circuits, not least through the classification of forebrain interneurons. Understanding the operation of interneuron networks however requires not only a wiring diagram that describes the innervation and postsynaptic targets of different GABAergic cells, but also an appreciation of the temporal dimension. Interneurons differ extensively in their intrinsic firing rates, their recruitment in different brain rhythms, and in their synaptic kinetics. Furthermore, in common with principal neurons, both the synapses innervating interneurons and the synapses made by these cells are highly modifiable, reflecting both their recent or remote use (short-term and long-term plasti... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926389 Mon, 30 May 2011 23:00:00 +0100 4926389 http://www.medworm.com/index.php?rid=4926391&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21632235%26dopt%3DAbstract Authors: Gupta N, Stopfer M Insects can learn, allowing them great flexibility for locating seasonal food sources and avoiding wily predators. Because insects are relatively simple and accessible to manipulation, they provide good experimental preparations for exploring mechanisms underlying sensory coding and memory. Here we review how the intertwining of memory with computation enables the coding, decoding, and storage of sensory experience at various stages of the insect olfactory system. Individual parts of this system are capable of multiplexing memories at different timescales, and conversely, memory on a given timescale can be distributed across different parts of the circuit. Our sampling of the olfactory system emphasizes the diversity of memories, and the importance of unders... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926391 Sun, 29 May 2011 23:00:00 +0100 4926391 http://www.medworm.com/index.php?rid=4926390&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21632236%26dopt%3DAbstract Authors: Koos T, Tecuapetla F, Tepper JM Although the notion that dopaminergic neurons utilize glutamate as a co-transmitter has long been supported by tantalizing molecular, immunocytochemical and electrophysiological evidence it has only been with the recent addition of optogenetic and other approaches that the existence and functional relevance of this mechanism could be unambiguously demonstrated. Here we discuss the possible mechanisms of action of glutamate released from mesoaccumbens dopaminergic neurons based on recently accumulated evidence. Surprisingly, rather then to confirm a role in conventional fast excitatory transmission, the latest evidence suggests that glutamate released from dopaminergic neurons may primarily act through different unconventional presynaptic and pos... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926390 Sun, 29 May 2011 23:00:00 +0100 4926390 http://www.medworm.com/index.php?rid=4926396&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21628097%26dopt%3DAbstract Authors: Maimon G When a monkey attends to a visual stimulus, neurons in visual cortex respond differently to that stimulus than when the monkey attends elsewhere. In the 25 years since the initial discovery, the study of attention in primates has been central to understanding flexible visual processing. Recent experiments demonstrate that visual neurons in mice and fruit flies are modulated by locomotor behaviors, like running and flying, in a manner that resembles attention-based modulations in primates. The similar findings across species argue for a more generalized view of state-dependent sensory processing and for a renewed dialogue among vertebrate and invertebrate research communities. PMID: 21628097 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiolo... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926396 Sat, 28 May 2011 23:00:00 +0100 4926396 http://www.medworm.com/index.php?rid=4926392&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21628098%26dopt%3DAbstract Authors: Olveczky BP How neural circuits underlie the acquisition and control of learned motor behaviors has traditionally been explored in monkeys and, more recently, songbirds. The development of genetic tools for functional circuit analysis in rodents, the availability of transgenic animals with well characterized phenotypes, and the relative ease with which rats and mice can be trained to perform various motor tasks, make rodents attractive models for exploring the neural circuit mechanisms underlying the acquisition and production of learned motor skills. Here we discuss the advantages and drawbacks of this approach, review recent trends and results, and outline possible strategies for wider adoption of rodents as a model system for complex motor learning. PMID: 21628098 [PubM... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926392 Sat, 28 May 2011 23:00:00 +0100 4926392 http://www.medworm.com/index.php?rid=4926397&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21624826%26dopt%3DAbstract Authors: Palmer CR, Kristan WB We review the influence of context on behavioral choice. Context can refer to external (environmental) factors such as the season or presence of predators and it can also refer to the internal or behavioral state of an animal. Usually, animals make decisions in the midst of other ongoing behaviors. We discuss recent findings on the impact of both types of contexts, focusing on how context gets encoded at the intersection between the sensory and motor systems, emphasizing the role of neuromodulators. We also review recent technological advances that have made feasible the exploration of neural correlates of decision making in freely moving, behaving animals. PMID: 21624826 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4926397 Fri, 27 May 2011 23:00:00 +0100 4926397 http://www.medworm.com/index.php?rid=4878957&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21605970%26dopt%3DAbstract Authors: Ting JT, Feng G The precise causal factors for obsessive-compulsive disorder (OCD) are not known, although, decades of research have honed in on the cortico-striatal-thalamo-cortical (CSTC) circuitry in the brain as a critical pathway involved in obsessions and the intimately linked compulsive-repetitive behaviors. Recent progress in human and mouse genetics have led to the identification of novel candidate susceptibility genes, which in turn have facilitated a more focused approach to unraveling the nature of circuitry dysfunction in OCD. The ability to perform invasive techniques in genetic animal models of OCD will be crucial for rapid advances in this field, and as such we review the most recent developments and highlight the importance of searching out common circuitry de... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4878957 Fri, 20 May 2011 23:00:00 +0100 4878957 http://www.medworm.com/index.php?rid=4878958&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21596554%26dopt%3DAbstract Authors: Gatto CL, Broadie K Heritable neurodevelopmental disorders are multifaceted disease conditions encompassing a wide range of symptoms including intellectual disability, cognitive dysfunction, autism and myriad other behavioral impairments. In cases where single, causative genetic defects have been identified, such as Angelman syndrome, Rett syndrome, Neurofibromatosis Type 1 and Fragile X syndrome, the classical Drosophila genetic system has provided fruitful disease models. Recent Drosophila studies have advanced our understanding of UBE3A, MECP2, NF1 and FMR1 function, respectively, in genetic, biochemical, anatomical, physiological and behavioral contexts. Investigations in Drosophila continue to provide the essential mechanistic understanding required to facilitate the conc... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4878958 Mon, 16 May 2011 23:00:00 +0100 4878958 http://www.medworm.com/index.php?rid=4878960&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21592779%26dopt%3DAbstract Authors: Enard W PURPOSE OF THE REVIEW: A reduced dosage of the transcription factor FOXP2 leads to speech and language impairments probably owing to deficits in cortical and subcortical neural circuits. Based on evolutionary sequence analysis it has been proposed that the two amino acid substitutions that occurred on the human lineage have been positively selected. Here I review recent studies investigating the functional consequences of these two substitutions and discuss how these first endeavors to study human brain evolution can be interpreted in the context of speech and language evolution. RECENT FINDINGS: Mice carrying the two substitutions in their endogenous Foxp2 gene show specific alterations in dopamine levels, striatal synaptic plasticity and neuronal morphology. Mice car... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4878960 Sun, 15 May 2011 23:00:00 +0100 4878960 http://www.medworm.com/index.php?rid=4878959&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21592780%26dopt%3DAbstract Authors: Sutherland R, Lehmann H We discuss very recent experiments with rodents addressing the idea that long-term memories initially depending on the hippocampus, over a prolonged period, become independent of it. No unambiguous recent evidence exists to substantiate that this occurs. Most experiments find that recent and remote memories are equally affected by hippocampus damage. Nearly all experiments that report spared remote memories suffer from two problems: retrieval could be based upon substantial regions of spared hippocampus and recent memory is tested at intervals that are of the same order of magnitude as cellular consolidation. Accordingly, we point the way beyond systems consolidation theories, both the Standard Model of Consolidation and the Multiple Trace Theory, and p... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4878959 Sun, 15 May 2011 23:00:00 +0100 4878959 http://www.medworm.com/index.php?rid=4878961&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21571522%26dopt%3DAbstract Authors: Colgin LL The hippocampus, a structure required for many types of memory, connects to the medial prefrontal cortex, an area that helps direct neuronal information streams during intentional behaviors. Increasing evidence suggests that oscillations regulate communication between these two regions. Theta rhythms may facilitate hippocampal inputs to the medial prefrontal cortex during mnemonic tasks and may also integrate series of functionally relevant gamma-mediated cell assemblies in the medial prefrontal cortex. During slow-wave sleep, temporal coordination of hippocampal sharp wave-ripples and medial prefrontal cortex spindles may be an important component of the process by which memories become hippocampus-independent. Studies using rodent models indicate that oscillatory p... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4878961 Thu, 12 May 2011 23:00:00 +0100 4878961 http://www.medworm.com/index.php?rid=4827980&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21555214%26dopt%3DAbstract Authors: Suvrathan A, Chattarji S Fragile X syndrome (FXS) is the most commonly inherited form of mental impairment and autism. Current understanding of the molecular and cellular mechanisms underlying FXS symptoms is derived mainly from studies on the hippocampus and cortex. However, FXS is also associated with strong emotional symptoms, which are likely to involve changes in the amygdala. Unfortunately, the synaptic basis of amygdalar dysfunction in FXS remains largely unexplored. Here we describe recent findings from mouse models of FXS that have identified synaptic defects in the basolateral amygdala that are in many respects distinct from those reported earlier in the hippocampus. Long-term potentiation and surface expression of AMPA-receptors are impaired. Further, presynaptic de... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4827980 Fri, 06 May 2011 23:00:00 +0100 4827980 http://www.medworm.com/index.php?rid=4828059&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21550798%26dopt%3DAbstract Authors: Oldenburg IA, Ding JB Modulatory interneurons such as, the cholinergic interneuron, are always a perplexing subject to study. Far from clear-cut distinctions such as excitatory or inhibitory, modulating interneurons can have many, often contradictory effects. The striatum is one of the most densely expressing brain areas for cholinergic markers, and actylcholine (ACh) plays an important role in regulating synaptic transmission and cellular excitability. Every cell type in the striatum has receptors for ACh. Yet even for a given cell type, ACh affecting different receptors can have seemingly opposing roles. This review highlights relevant effects of ACh on medium spiny neurons (MSNs) of the striatum and suggests how its many effects may work in concert to modulate MSN firing pr... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4828059 Thu, 05 May 2011 23:00:00 +0100 4828059 http://www.medworm.com/index.php?rid=4828083&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21546244%26dopt%3DAbstract Authors: Goosens KA For many years, the hippocampal formation has been implicated in the regulation of negative emotion, yet the nature of this link has remained elusive. Recent studies have made important links between the hippocampus and regulation of stress hormones that affect aversive memory. Additional studies have shown that the hippocampus regulates the gating of fear by contextual information. An emerging literature also links the hippocampus to prediction errors during fear learning and extinction. The mechanisms by which the hippocampus regulates negative emotion are clearly complicated, but suggest that interventions aimed at restoring normal hippocampal function may help with disorders of negative affect, such as depression or post-traumatic stress disorder and depression.... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4828083 Mon, 02 May 2011 23:00:00 +0100 4828083 http://www.medworm.com/index.php?rid=4828124&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21531543%26dopt%3DAbstract This article reviews evidence for an important role of the striatum and its interaction with the prefrontal cortex and suggests a variety of ways by which changes in dopamine transmission can bias high-level cognition. PMID: 21531543 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4828124 Thu, 28 Apr 2011 23:00:00 +0100 4828124 http://www.medworm.com/index.php?rid=4828104&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21531544%26dopt%3DAbstract Authors: Ito M, Doya K Accumulating evidence shows that the neural network of the cerebral cortex and the basal ganglia is critically involved in reinforcement learning. Recent studies found functional heterogeneity within the cortico-basal ganglia circuit, especially in its ventromedial to dorsolateral axis. Here we review computational issues in reinforcement learning and propose a working hypothesis on how multiple reinforcement learning algorithms are implemented in the cortico-basal ganglia circuit using different representations of states, values, and actions. PMID: 21531544 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4828104 Thu, 28 Apr 2011 23:00:00 +0100 4828104 http://www.medworm.com/index.php?rid=4828141&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21530233%26dopt%3DAbstract Authors: Baudry A, Mouillet-Richard S, Launay JM, Kellermann O The increasing incidence of depressive spectrum disorders worldwide, together with the failure of current medication to effectively treat a significant proportion of cases, calls for a better knowledge of the physiopathology of depression and of the therapeutic action of antidepressants. Recent research has unveiled an array of new mechanisms through which antidepressant drugs help restore neuronal plasticity and neurotransmission. In this review, we summarize the latest advances in the field, focusing on the effectors and molecular pathways that sustain the action of antidepressants. Grasping the overall brain response to antidepressants, with an integrated overview of the neurotransmitter systems, signaling cascades and n... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4828141 Tue, 26 Apr 2011 23:00:00 +0100 4828141 http://www.medworm.com/index.php?rid=4774114&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21501959%26dopt%3DAbstract Authors: Luksys G, Sandi C Stress has complex effects on memory function that can vary depending on the type of information that is learned and in relation to inter-individual characteristics. Recent work has also shown that stress can switch performance between memory systems, biasing it toward habit in detriment of spatial or goal-directed strategies. In addition, novel synaptic mechanisms have been implicated in the effects of stress in plasticity and memory. Computational modeling is emerging as a useful approach to integrate and to ascertain neural and cognitive computations underlying different effects of stress in memory. Having provided novel explanations for the inverted-U-shaped relationship between stress and cognitive performance, model-based analysis studies can improve ou... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4774114 Fri, 15 Apr 2011 23:00:00 +0100 4774114 http://www.medworm.com/index.php?rid=4774116&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21498067%26dopt%3DAbstract This article reviews some of the theoretical advances offered by these models, focusing on motor and cognitive action selection, learning, and the interaction between multiple corticostriatal circuits in selection and learning. PMID: 21498067 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4774116 Thu, 14 Apr 2011 23:00:00 +0100 4774116 http://www.medworm.com/index.php?rid=4774115&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21498068%26dopt%3DAbstract Authors: Goda Y, Sabatini BL PMID: 21498068 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4774115 Thu, 14 Apr 2011 23:00:00 +0100 4774115 http://www.medworm.com/index.php?rid=4774117&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21470846%26dopt%3DAbstract Authors: Gordon JA The hippocampus and medial prefrontal cortex subserve spatial working memory in rodents. Recent evidence has demonstrated functional interactions between these brain regions in the form of sychronization of oscillatory activity during behavior. The nature of this synchrony and its relationship to behavioral performance suggests an important role in the function of the hippocampal-prefrontal circuit. PMID: 21470846 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4774117 Sun, 03 Apr 2011 23:00:00 +0100 4774117 http://www.medworm.com/index.php?rid=4669567&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21450454%26dopt%3DAbstract Authors: Xu W Activity-dependent modification of excitatory synaptic transmission is a fundamental mechanism for developmental plasticity of the neural circuits and experience-dependent plasticity. Synaptic glutamatergic receptors including AMPA receptors and NMDA receptors (AMPARs and NMDARs) are embedded in the postsynaptic density, a highly organized protein network. Overwhelming data have shown that PSD-95-like membrane associated guanylate kinases (PSD-MAGUKs), a major family of scaffold proteins at glutamatergic synapses, regulate basal synaptic AMPAR function and trafficking. It is now clear that PSD-MAGUKs have multifaceted functions in regulating both basal synaptic transmission and synaptic plasticity. Here we discuss recent advancements in understanding the roles of PSD-95 a... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4669567 Sun, 27 Mar 2011 23:00:00 +0100 4669567 http://www.medworm.com/index.php?rid=4669568&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21441021%26dopt%3DAbstract Authors: Wilson RI Synapses exhibit diverse functional properties, and it seems likely that these properties are specialized to perform specific computations. The Drosophila antennal lobe provides a useful experimental preparation for exploring the relationship between synaptic physiology and neural computations. This review summarizes recent progress in describing synaptic properties in the Drosophila antennal lobe. These studies reveal that several types of synapses in this circuit are highly specialized, and that these specializations are in some cases under tight regulatory control. These synaptic specializations can be understood in terms of the computational features they confer on the circuit. Specifically, many of these properties appear to promote odor detection when odor conc... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4669568 Fri, 25 Mar 2011 00:00:00 +0100 4669568 http://www.medworm.com/index.php?rid=4669571&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21429734%26dopt%3DAbstract Authors: Bornstein AM, Daw ND The basal ganglia, in particular the striatum, are central to theories of behavioral control, and often identified as a seat of action selection. Reinforcement learning (RL) models-which have driven much recent experimental work on this region-cast striatum as a dynamic controller, integrating sensory and motivational information to construct efficient and enriching behavioral policies. Befitting this informationally central role, the BG sit at the nexus of multiple anatomical 'loops' of synaptic projections, connecting a wide range of cortical and subcortical structures. Numerous pioneering anatomical studies conducted over the past several decades have meticulously catalogued these loops, and labeled them according to the inferred functions of the connec... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4669571 Mon, 21 Mar 2011 00:00:00 +0100 4669571 http://www.medworm.com/index.php?rid=4669570&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21429735%26dopt%3DAbstract Authors: Yasuda R, Murakoshi H During the induction of plasticity of dendritic spines, many intracellular signaling pathways are spatially and temporally regulated to co-ordinate downstream cellular processes in different dendritic micron-domains. Recent advent of imaging technology based on fluorescence resonance energy transfer (FRET) has allowed the direct monitoring of the spatiotemporal regulation of signaling activity in spines and dendrites during synaptic plasticity. In particular, the activity of three small GTPase proteins HRas, Cdc42, and RhoA, which share similar structure and mobility on the plasma membrane, displayed different spatial spreading patterns: Cdc42 is compartmentalized in the stimulated spines while RhoA and HRas spread into dendrites over 5-10μm. These measu... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4669570 Mon, 21 Mar 2011 00:00:00 +0100 4669570 http://www.medworm.com/index.php?rid=4669569&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21429736%26dopt%3DAbstract Authors: Benchenane K, Tiesinga PH, Battaglia FP We consider the potential role of oscillations in the prefrontal cortex (PFC) in mediating attention, working memory and memory consolidation. Activity in the theta, beta, and gamma bands is related to communication between PFC and different brain areas. While gamma/beta oscillations mediate bottom-up and top-down interactions between PFC and visual cortices, related to attention, theta rhythms are engaged by hippocampal/PFC interplay. These interactions are dynamic, depending on the nature and relevance of the information currently being processed. The profound modifications of the PFC neuronal network associated with changes in oscillatory coherence are controlled by neuromodulators such as dopamine, which thereby allow or prevent the ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4669569 Mon, 21 Mar 2011 00:00:00 +0100 4669569 http://www.medworm.com/index.php?rid=4669573&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21420852%26dopt%3DAbstract Authors: Kravitz AV, Kreitzer AC Recent advances in optogenetics have permitted investigations of specific cell types in the nervous system with unprecedented precision and control. This review will discuss the use of optogenetic techniques in the study of mammalian neural circuitry in vivo, as well as practical and theoretical considerations in their application. PMID: 21420852 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4669573 Fri, 18 Mar 2011 00:00:00 +0100 4669573 http://www.medworm.com/index.php?rid=4669572&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21420853%26dopt%3DAbstract Authors: van der Meer MA, Redish AD Extensive evidence implicates the ventral striatum in multiple distinct facets of action selection. Early work established a role in modulating ongoing behavior, as engaged by the energizing and directing influences of motivationally relevant cues and the willingness to expend effort in order to obtain reward. More recently, reinforcement learning models have suggested the notion of ventral striatum primarily as an evaluation step during learning, which serves as a critic to update a separate actor. Recent computational and experimental work may provide a resolution to the differences between these two theories through a careful parsing of behavior and the instrinsic heterogeneity that characterizes this complex structure. PMID: 21420853 [PubMed ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4669572 Fri, 18 Mar 2011 00:00:00 +0100 4669572 http://www.medworm.com/index.php?rid=4613141&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21376567%26dopt%3DAbstract Authors: Chalifoux JR, Carter AG Neuromodulators have complex effects on both the presynaptic release and postsynaptic detection of neurotransmitters. Here we describe recent advances in our understanding of synaptic modulation by metabotropic GABA(B) receptors. By inhibiting multivesicular release from the presynaptic terminal, these receptors decrease the synaptic glutamate signal. GABA(B) receptors also inhibit the Ca(2+) permeability of NMDA receptors to decrease Ca(2+) signals in postsynaptic spines. These new findings highlight the importance of GABA(B) receptors in regulating many aspects of synaptic transmission. They also point to novel questions about the spatiotemporal dynamics and sources of synaptic modulation in the brain. PMID: 21376567 [PubMed - as supplied by publi... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4613141 Wed, 02 Mar 2011 00:00:00 +0100 4613141 http://www.medworm.com/index.php?rid=4550693&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21371881%26dopt%3DAbstract Authors: Girardeau G, Zugaro M During slow wave sleep and quiet wakefulness, the hippocampus generates high frequency field oscillations (ripples) during which pyramidal neurons replay previous waking activity in a temporally compressed manner. As a result, reactivated firing patterns occur within shorter time windows propitious for synaptic plasticity within the hippocampal network and in downstream neocortical structures. This is consistent with the long-held view that ripples participate in strengthening and reorganizing memory traces, possibly by mediating information transfer to neocortical areas. Recent studies have confirmed that ripples and associated neuronal reactivations play a causal role in memory consolidation during sleep and rest. However, further research will be neces... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550693 Tue, 01 Mar 2011 00:00:00 +0100 4550693 http://www.medworm.com/index.php?rid=4550694&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21367599%26dopt%3DAbstract Authors: Inokuchi K A growing body of evidence indicates that adult neurogenesis is involved in the modulation of certain types of hippocampus-dependent memory. Recent studies suggest that newly born neurons play a key role in pattern separation mediated by the dentate gyrus, in systems consolidation, through which memory becomes progressively independent of the hippocampus, and in social memory-based reproductive behavior. Furthermore, neural activity and learning are now thought to regulate the proliferation of neuronal precursors as well as the survival and apoptosis of new neurons. Moreover, these processes also affect the development of the dendritic arbor and dendritic spines of new neurons, thereby modulating the integration of adult-born neurons into the functional neural circu... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550694 Mon, 28 Feb 2011 00:00:00 +0100 4550694 http://www.medworm.com/index.php?rid=4550697&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21353526%26dopt%3DAbstract Authors: Fioravante D, Regehr WG Synapses exhibit several forms of short-term plasticity that play a multitude of computational roles. Short-term depression suppresses neurotransmitter release for hundreds of milliseconds to tens of seconds; facilitation and post-tetanic potentiation lead to synaptic enhancement lasting hundreds of milliseconds to minutes. Recent advances have provided insight into the mechanisms underlying these forms of plasticity. Vesicle depletion, as well as inactivation of both release sites and calcium channels, contribute to synaptic depression. Mechanisms of short-term enhancement include calcium channel facilitation, local depletion of calcium buffers, increases in the probability of release downstream of calcium influx, altered vesicle pool properties, and i... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550697 Wed, 23 Feb 2011 00:00:00 +0100 4550697 http://www.medworm.com/index.php?rid=4550696&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21353527%26dopt%3DAbstract Authors: Vann SD, Albasser MM Recognition and spatial memory are typically associated with the perirhinal cortex and hippocampal formation, respectively. Solely focusing on these structures for these specific mnemonic functions may, however, be limiting progress in the field. The distinction between these subdivisions of memory is becoming less defined as, for example, hippocampal cells traditionally considered to encode locations also encode place-object associations. There is increasing evidence for the involvement of overlapping networks of brain structures for aspects of both spatial and recognition memory. Future models of spatial and recognition memory will have to extend beyond the hippocampus and perirhinal cortex to incorporate a wider network of cortical and subcortical struc... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550696 Wed, 23 Feb 2011 00:00:00 +0100 4550696 http://www.medworm.com/index.php?rid=4550695&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21353528%26dopt%3DAbstract Authors: van Welie I, Smith IT, Watt AJ The cerebellar cortical circuit with its organized and repetitive structure provides an excellent model system for studying how brain circuits are formed during development. The emergence of the mature brain requires that appropriate synaptic connections are formed and refined, which in the rodent cerebellum occurs primarily during the first three postnatal weeks. Developing circuits typically differ substantially from their mature counterparts, which suggests that development may not simply involve synaptic refinement, but rather involves restructuring of key synaptic components and network connections, in a manner reminiscent of metamorphosis. Here, we discuss recent evidence that, taken together, suggests that transient features of developing ... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550695 Wed, 23 Feb 2011 00:00:00 +0100 4550695 http://www.medworm.com/index.php?rid=4550700&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21349697%26dopt%3DAbstract Authors: Mayer ML Ionotropic glutamate receptors (iGluRs) are ligand gated ion channels that mediate excitatory synaptic transmission in the brain of vertebrates. A rapidly growing body of crystal structures for isolated iGluR extracellular domains, and more recently a full length AMPA receptor, combined with data from electrophysiological experiments and MD simulations, provides a framework that makes it possible to investigate the molecular basis for assembly, gating and modulation. These unprecedented advances in structural biology are constantly challenged by novel functional properties that emerge despite decades of functional analysis, and by a growing family of auxiliary proteins that modulate iGluR activity and assembly. PMID: 21349697 [PubMed - as supplied by publisher] (S... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550700 Tue, 22 Feb 2011 00:00:00 +0100 4550700 http://www.medworm.com/index.php?rid=4550699&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21349698%26dopt%3DAbstract Authors: Ch'ng TH, Martin KC Signals generated in distal subcellular compartments of neurons must often travel long distances to the nucleus to trigger changes in gene expression. This retrograde signaling is critical to the development, function, and survival of neural circuits, and neurons have evolved multiple mechanisms to transmit signals over long distances. In this review, we briefly summarize the range of mechanisms whereby distally generated signals are transported to neuronal nuclei. We then focus on the transport of soluble signals from the synapse to the nucleus during neuronal plasticity. PMID: 21349698 [PubMed - as supplied by publisher] (Source: Current Opinion in Neurobiology) Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550699 Tue, 22 Feb 2011 00:00:00 +0100 4550699 http://www.medworm.com/index.php?rid=4550698&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21349699%26dopt%3DAbstract Authors: Oesch NW, Wade Kothmann W, Diamond JS In the central nervous system, space is at a premium. This is especially true in the retina, where synapses, cells, and circuitry have evolved to maximize signal-processing capacity within a thin, optically transparent tissue. For example, at some retinal synapses, single presynaptic active zones contact multiple postsynaptic targets; some individual neurons perform completely different tasks depending on visual conditions, while others execute hundreds of circuit computations in parallel; and the retinal network adapts, at various levels, to the ever-changing visual world. Each of these features reflects efficient use of limited cellular resources to optimally encode visual information. PMID: 21349699 [PubMed - as supplied by publishe... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550698 Tue, 22 Feb 2011 00:00:00 +0100 4550698 http://www.medworm.com/index.php?rid=4550701&cid=s_35495_25_f&fid=35495&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21342763%26dopt%3DAbstract Authors: Yuzaki M Cbln1 is a newly identified synaptic organizer belonging to the C1q family. Unlike other synaptic organizers, a deficiency in Cbln1 is sufficient to cause a severe reduction in the number of synapses between cerebellar Purkinje cells and parallel fibers (PFs). Furthermore, Cbln1 can rapidly induce synaptogenesis and is necessary for maintaining normal synapses in the mature cerebellum in vivo. Cbln1 was recently identified as the missing ligand for the orphan glutamate receptor δ2 (GluD2), which is expressed in Purkinje cells. Furthermore, Cbln1 released from PFs binds to neurexin (NRX) expressed on the presynaptic PFs and GluD2 at the postsynaptic site. The NRX/Cbln1/GluD2 tripartite complex is resistant to low extracellular Ca(2+) levels and serves as a unique bidi... Current Opinion in Neurobiology journals http://www.medworm.com/rss/comments.php?id=4550701 Sun, 20 Feb 2011 00:00:00 +0100 4550701