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 'Cerebral Cortex' source. Sun, 21 Mar 2010 15:30:26 +0100 http://www.medworm.com/index.php?rid=3356422&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F997%3Frss%3D1 We examined the synaptic organization of reciprocal connections between the temporal cortex and the dorsal (Pd) and central (Pc) subdivisions of the tree shrew pulvinar nucleus, regions innervated by the medial and lateral superior colliculus, respectively. Both Pd and Pc subdivisions project topographically to 2 separate regions of the temporal cortex; small injections of anterograde tracers placed in either Pd or Pc labeled 2 foci of terminals in the temporal cortex. Pulvinocortical pathways innervated layers I–IV, with beaded axons oriented perpendicular to the cortical surface, where they synapsed with spines that did not contain gamma amino butyric acid (GABA), likely located on the apical dendrites of pyramidal cells. Projections from the temporal cortex to the Pd and Pc origin... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356422 Thu, 11 Mar 2010 23:48:53 +0100 3356422 http://www.medworm.com/index.php?rid=3356421&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F982%3Frss%3D1 Cholinergic neurotransmission in the medial prefrontal cortex (mPFC) is critical for normal processing of cue detection and cognitive performance. However, the mechanism by which cholinergic system modifies mPFC synaptic function remains unclear. Here we show that activation of muscarinic acetylcholine receptors (mAChRs) by carbamoylcholine (CCh) induces long-term depression (CCh-LTD) of excitatory synaptic transmission on mPFC layer V pyramidal neurons. The induction of CCh-LTD is dependent on M1 mAChR activation but does not require N-methyl-D-aspartate receptor activation or coincident synaptic stimulation. Activation of phospholipase C (PLC), protein kinase C (PKC), and postsynaptic Ca2+ release from inositol 1,4,5-triphosphate (IP3) receptor–sensitive internal stores are require... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356421 Thu, 11 Mar 2010 23:48:53 +0100 3356421 http://www.medworm.com/index.php?rid=3356420&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F966%3Frss%3D1 We examined the histological organization of striate (V1) and 2 extrastriate (V2 and ventral posterior) cortical areas in humans, 5 ape species, and a macaque. The cytoarchitectural patterns of visual areas were compared across species using quantitative descriptions of cell volume densities and laminar patterns. We also investigated potential scaling relationships between cell volume density and several brain, body, and visual system variables. The results suggest that interspecific variability in the cytoarchitectural organization of visual system structures can arise independently of global brain and body size scaling relationships. In particular, species-specific differences in cell volume density seem to be most closely linked to the size of structures in the visual system. (Source: C... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356420 Thu, 11 Mar 2010 23:48:53 +0100 3356420 http://www.medworm.com/index.php?rid=3356419&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F953%3Frss%3D1 The cerebellum processes information from functionally diverse regions of the cerebral cortex. Cerebellar input and output nuclei have connections with prefrontal, parietal, and sensory cortex as well as motor and premotor cortex. However, the topography of the connections between the cerebellar and cerebral cortices remains largely unmapped, as it is relatively unamenable to anatomical methods. We used resting-state functional magnetic resonance imaging to define subregions within the cerebellar cortex based on their functional connectivity with the cerebral cortex. We mapped resting-state functional connectivity voxel-wise across the cerebellar cortex, for cerebral–cortical masks covering prefrontal, motor, somatosensory, posterior parietal, visual, and auditory cortices. We found ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356419 Thu, 11 Mar 2010 23:48:53 +0100 3356419 http://www.medworm.com/index.php?rid=3356418&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F941%3Frss%3D1 Transcriptional changes in neurons underpin the long-lived cellular response to environmental stimuli, and cAMP-responsive element-binding protein (CREB1) has been implicated in this process. Exposure to psychostimulants such as cocaine results in persistent neuronal plasticity in cortical circuitry that likely modulates the motivation to use the drug again. To examine whether CREB1 in cortical glutamatergic neurons was implicated in cocaine use, we developed conditional CREB1 mutants that exhibit ablation of functional CREB1 in the cortex and hippocampus. Here we report that CREB1 mutants show normal locomotor responses to acute and chronic cocaine and develop a place preference for cocaine. However, CREB1 mutants demonstrate a diminished drive to self-administer cocaine under operant con... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356418 Thu, 11 Mar 2010 23:48:53 +0100 3356418 http://www.medworm.com/index.php?rid=3356417&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F929%3Frss%3D1 Uncertainty about potential negative future outcomes can cause stress and is a central feature of anxiety disorders. The stress and anxiety associated with uncertain situations may lead individuals to overestimate the frequency with which uncertain cues are followed by negative outcomes, an example of covariation bias. Using functional magnetic resonance imaging, we found that uncertainty-related expectations modulated neural responses to aversion. Insula and amygdala responses to aversive pictures were larger after an uncertain cue (that preceded aversive or neutral pictures) than a certain cue (that always preceded aversive pictures). Anticipatory anterior cingulate cortex (ACC) activity elicited by the cues was inversely associated with the insula and amygdala responses to aversive pict... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356417 Thu, 11 Mar 2010 23:48:53 +0100 3356417 http://www.medworm.com/index.php?rid=3356416&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F912%3Frss%3D1 The present study establishes an electrophysiological index of lexical access in speech production by exploring the locus of the frequency and cognate effects during overt naming. We conducted 2 event-related potential (ERP) studies with 16 Spanish–Catalan bilinguals performing a picture naming task in Spanish (L1) and 16 Catalan–Spanish bilinguals performing a picture naming task in Spanish (L2). Behavioral results showed a clear frequency effect and an interaction between frequency and cognate status. The ERP elicited during the production of high-frequency words diverged from the low-frequency ERP between 150 and 200 ms post-target presentation and kept diverging until voice onset. The same results were obtained when comparing cognate and noncognate conditions. Positive corr... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356416 Thu, 11 Mar 2010 23:48:53 +0100 3356416 http://www.medworm.com/index.php?rid=3356415&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F898%3Frss%3D1 We report that, in contrast to time-locked spikes generated by EPSPAMPA in control DGCs, aberrant EPSPKA are associated with long-lasting plateaus and jittered spikes during single-spike mode firing. This is mediated by a selective voltage-dependent amplification of EPSPKA through persistent sodium current (INaP) activation. In control DGCs, a current injection of a waveform mimicking the slow shape of EPSPKA activates INaP and generates jittered spikes. Conversely in epileptic rats, blockade of EPSPKA or INaP restores the temporal precision of EPSP–spike coupling. Importantly, EPSPKA not only decrease spike timing precision at recurrent mossy fiber synapses but also at perforant path synapses during synaptic integration through INaP activation. We conclude that a selective interplay... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356415 Thu, 11 Mar 2010 23:48:53 +0100 3356415 http://www.medworm.com/index.php?rid=3356414&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F884%3Frss%3D1 We investigated the postnatal effects of embryonic knockdown and overexpression of the candidate dyslexia gene homolog Kiaa0319. We used in utero electroporation to transfect cells in E15/16 rat neocortical ventricular zone with either 1) small hairpin RNA (shRNA) vectors targeting Kiaa0319, 2) a KIAA0319 expression construct, 3) Kiaa0319 shRNA along with KIAA0319 expression construct ("rescue"), or 4) a scrambled version of Kiaa0319 shRNA. Knockdown, but not overexpression, of Kiaa0319 resulted in periventricular heterotopias that contained large numbers of both transfected and non–transfected neurons. This suggested that Kiaa0319 shRNA disrupts neuronal migration by cell autonomous as well as non–cell autonomous mechanisms. Of the Kiaa0319 shRNA–transfected neurons that... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356414 Thu, 11 Mar 2010 23:48:53 +0100 3356414 http://www.medworm.com/index.php?rid=3356413&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F873%3Frss%3D1 The prelimbic (PL) region of the prefrontal cortex and the posterior subregion of the dorsomedial striatum (pDMS) are components of a corticostriatal circuit subserving instrumental learning. Here, we examined whether dopamine (DA) signals conveyed to the PL and pDMS are critical for instrumental learning. Rats with 6-hydroxydopamine or vehicle infusion into the PL and pDMS were trained to press 2 levers, either for food pellets or a sucrose solution. Thereafter, we tested whether the animals were sensitive 1) to a selective degradation of 1 of 2 outcomes using a specific satiety procedure and 2) to a selective degradation of 1 of 2 contingencies controlling instrumental behavior. Rats with PL DA depletion displayed a reduced rate of lever presses but appeared to be sensitive to outcome de... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356413 Thu, 11 Mar 2010 23:48:53 +0100 3356413 http://www.medworm.com/index.php?rid=3356412&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F859%3Frss%3D1 In this study, electroencephalogram and functional magnetic resonance imaging (fMRI) data were recorded in separate experiments that each introduced different types of visual interference during a period of WM maintenance: distraction (irrelevant stimuli) and interruption (stimuli that required attention). The data converged to reveal that regardless of the type of interference, the magnitude of processing interfering stimuli in the visual cortex (as rapidly as 100 ms) predicted subsequent WM recognition accuracy for stored items. fMRI connectivity analyses suggested that in the presence of distraction, encoded items were maintained throughout the delay period via connectivity between the middle frontal gyrus and visual association cortex, whereas memoranda were not maintained when subject... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356412 Thu, 11 Mar 2010 23:48:53 +0100 3356412 http://www.medworm.com/index.php?rid=3356411&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F846%3Frss%3D1 To investigate the role of the medial parietal region (MPR), comprising area 7m and the retrosplenial and posterior cingulate cortices, in spatial navigation, we analyzed the spatial aspect of the responses of the MPR neurons in monkeys while they actively performed a navigation task in a virtual environment. One-third of the analyzed MPR neurons were activated depending on the location of the monkeys in the environment, that is, showed place-selective responses. Some neurons showed varying responses based on the starting point (SP) or destination. We further investigated the responses of the place-selective neurons when the monkeys were shown animations of the entire navigation route, including the preferred field, and a segment of the route, including an area around the preferred field, ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356411 Thu, 11 Mar 2010 23:48:53 +0100 3356411 http://www.medworm.com/index.php?rid=3356410&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F837%3Frss%3D1 Previous studies have reported abnormal prefrontal and cingulate activity during attentional control processing in schizophrenia. However, it is not clear how variation in attentional control load modulates activity within these brain regions in this brain disorder. The aim of this study in schizophrenia is to investigate the impact of increasing levels of attentional control processing on prefrontal and cingulate activity. Blood oxygen level–dependent (BOLD) responses of 16 outpatients with schizophrenia were compared with those of 21 healthy subjects while performing a task eliciting increasing levels of attentional control during event-related functional magnetic resonance imaging at 3 T. Results showed reduced behavioral performance in patients at greater attentional control leve... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356410 Thu, 11 Mar 2010 23:48:53 +0100 3356410 http://www.medworm.com/index.php?rid=3356409&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F826%3Frss%3D1 To understand sensory representation in cortex, it is crucial to identify its constituent cellular components based on cell-type–specific criteria. With the identification of cell types, an important question can be addressed: to what degree does the cellular properties of neurons depend on cortical location? We tested this question using pyramidal neurons in layer 5 (L5) because of their role in providing major cortical output to subcortical targets. Recently developed transgenic mice with cell-type–specific enhanced green fluorescent protein labeling of neuronal subtypes allow reliable identification of 2 cortical cell types in L5 throughout the entire neocortex. A comprehensive investigation of anatomical and functional properties of these 2 cell types in visual and somatose... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356409 Thu, 11 Mar 2010 23:48:52 +0100 3356409 http://www.medworm.com/index.php?rid=3356408&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F813%3Frss%3D1 One influential account asserts that the anterior temporal lobe (ATL) is a domain-general hub for semantic memory. Other evidence indicates it is part of a domain-specific social cognition system. Arbitrating these accounts using functional magnetic resonance imaging has previously been difficult because of magnetic susceptibility artifacts in the region. The present study used parameters optimized for imaging the ATL, and had subjects encode facts about unfamiliar people, buildings, and hammers. Using both conjunction and region of interest analyses, person-selective responses were observed in both the left and right ATL. Neither building-selective, hammer-selective nor domain-general responses were observed in the ATLs, although they were observed in other brain regions. These findings w... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356408 Thu, 11 Mar 2010 23:48:52 +0100 3356408 http://www.medworm.com/index.php?rid=3356407&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F804%3Frss%3D1 Sensory experiences have important roles in the functional development of the mammalian auditory cortex. Here, we show how early continuous noise rearing influences spatial sensitivity in the rat primary auditory cortex (A1) and its underlying mechanisms. By rearing infant rat pups under conditions of continuous, moderate level white noise, we found that noise rearing markedly attenuated the spatial sensitivity of A1 neurons. Compared with rats reared under normal conditions, spike counts of A1 neurons were more poorly modulated by changes in stimulus location, and their preferred locations were distributed over a larger area. We further show that early continuous noise rearing induced significant decreases in glutamic acid decarboxylase 65 and -aminobutyric acid (GABA)A receptor 1 subunit... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356407 Thu, 11 Mar 2010 23:48:52 +0100 3356407 http://www.medworm.com/index.php?rid=3356406&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F798%3Frss%3D1 Glutamate is the major excitatory neurotransmitter in the brain and therefore important for cognitive functions. The aim of the study was to investigate if administration of the N-methyl-D-aspartate receptor antagonist memantine to healthy individuals would affect brain activation when performing an auditory attention task. The task was a variant of a dichotic listening task with different instructions that tap demands for attention and cognitive control. We asked the question if memantine administration would lead to reduction in glutamatergic neurotransmission in areas related to attention and cognitive control. Left and right frontal glutamate and glutamine (Glx) concentrations were measured, using 1H-MR spectroscopy. Twenty-five healthy adults were scanned twice in a counterbalanced de... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356406 Thu, 11 Mar 2010 23:48:52 +0100 3356406 http://www.medworm.com/index.php?rid=3356405&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F783%3Frss%3D1 Both animal and human data suggest that stimulation of the noradrenergic system may influence neuronal excitability in regions engaged in sensory processing and visuospatial attention. We tested the hypothesis that the neural mechanisms subserving motor performance in tasks relying on the visuomotor control of goal-directed hand movements might be modulated by noradrenergic influences. Healthy subjects were stimulated using the selective noradrenaline reuptake inhibitor reboxetine (RBX) in a placebo-controlled crossover design. Functional magnetic resonance imaging and dynamic causal modeling (DCM) were used to assess drug-related changes in blood oxygen level–dependent activity and interregional connectivity while subjects performed a joystick task requiring goal-directed movements.... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356405 Thu, 11 Mar 2010 23:48:52 +0100 3356405 http://www.medworm.com/index.php?rid=3356404&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F773%3Frss%3D1 Speech comprehension remains largely preserved in older adults despite significant age-related neurophysiological change. However, older adults’ performance declines more rapidly than that of young adults when listening conditions are challenging. We investigated the cortical network underlying speech comprehension in healthy aging using short sentences differing in syntactic complexity, with processing demands further manipulated through speech rate. Neural activity was monitored using blood oxygen level–dependent functional magnetic resonance imaging. Comprehension of syntactically complex sentences activated components of a core sentence-processing network in both young and older adults, including the left inferior and middle frontal gyri, left inferior parietal cortex, and ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356404 Thu, 11 Mar 2010 23:48:52 +0100 3356404 http://www.medworm.com/index.php?rid=3356403&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2F759%3Frss%3D1 We recently showed that transcranial magnetic stimulation (TMS) over the right parietal eye fields disrupts memory of object features and locations across saccades. We applied TMS over the frontal eye fields (FEF) as subjects compared the feature details of visual targets presented either within a single eye fixation (Fixation Task) or across a saccade (Saccade Task). TMS pulses were randomly delivered at one of 3 time intervals around the time of the saccade, or at equivalent times in the Fixation Task. A No-TMS control confirmed that subjects could normally retain ~3 visual features. TMS in the Fixation Task had no effect compared with No-TMS, but differences among TMS times were found during right FEF stimulation. TMS over either the right or left FEF disrupted memory performance in the... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356403 Thu, 11 Mar 2010 23:48:52 +0100 3356403 http://www.medworm.com/index.php?rid=3356402&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2FNP-c%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356402 Thu, 11 Mar 2010 23:48:52 +0100 3356402 http://www.medworm.com/index.php?rid=3356401&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2FNP-b%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356401 Thu, 11 Mar 2010 23:48:52 +0100 3356401 http://www.medworm.com/index.php?rid=3356400&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2FNP-a%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356400 Thu, 11 Mar 2010 23:48:52 +0100 3356400 http://www.medworm.com/index.php?rid=3356399&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F4%2FNP%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3356399 Thu, 11 Mar 2010 23:48:52 +0100 3356399 http://www.medworm.com/index.php?rid=3264684&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F743%3Frss%3D1 In this study, we identify a link between dopamine, episodic memory networks, and aging, using pharmacological functional magnetic resonance imaging. Young and older adults received a D2-like agonist (Bromocriptine, 1.25 mg), a D2-like antagonist (Sulpiride, 400 mg), and Placebo, in a double-blind crossover procedure. We observed group differences, during memory encoding, in medial temporal, frontal, and striatal regions and moreover, these regions were differentially sensitive across groups to dopaminergic perturbation. These findings suggest that brain systems underlying memory show age-related changes and that dopaminergic function may be key in understanding these changes. That these changes have behavioral consequences was suggested by the observation that drug modulations were most p... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264684 Fri, 12 Feb 2010 06:01:55 +0100 3264684 http://www.medworm.com/index.php?rid=3264683&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F730%3Frss%3D1 Neural changes that occurred during human evolution to support language are poorly understood. As a basis of comparison to humans, we used design-based stereological methods to estimate volumes, total neuron numbers, and neuron densities in Brodmann's areas 44 and 45 in both cerebral hemispheres of 12 chimpanzees (Pan troglodytes), one of our species’ closest living relatives. We found that the degree of interindividual variation in the topographic location and quantitative cytoarchitecture of areas 44 and 45 in chimpanzees was comparable to that seen in humans from previous studies. However, in contrast to the documented asymmetries in humans, we did not find significant population-level hemispheric asymmetry for any measures of areas 44 and 45 in chimpanzees. Furthermore, there was... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264683 Fri, 12 Feb 2010 06:01:55 +0100 3264683 http://www.medworm.com/index.php?rid=3264682&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F720%3Frss%3D1 It is a familiar and intuitive notion that human numerical and logical reasoning skills are tightly related. However, very little is known about the interaction between numerical knowledge and logical reasoning in the brain. Using functional magnetic resonance imaging in healthy subjects, we investigated ordered relations as they are expressed in number (4 is greater than 2) and in transitive reasoning (A is to the left of C after receiving; A is to the left of B; B is to the left of C) in order to determine the extent to which the same neural substrates support both. We found that representing an ordered series verbally learned by transitive reasoning draws on the representations of numbers in the anterior intraparietal sulcus. We further observed that, unlike numbers, transitive series a... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264682 Fri, 12 Feb 2010 06:01:55 +0100 3264682 http://www.medworm.com/index.php?rid=3264681&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F704%3Frss%3D1 In this study, forelimb organizations and output properties of the supplementary motor area (SMA) and the dorsal cingulate motor area (CMAd) were assessed and compared with primary motor cortex (M1). Stimulus-triggered averages of electromyographic activity from 24 muscles of the forelimb were computed from layer V sites of 2 rhesus monkeys performing a reach-to-grasp task. No clear segregation of the forelimb representation of proximal and distal muscles was found in SMA. In CMAd, sites producing poststimulus effects in proximal muscles tended to be located caudal to distal muscle sites, although the number of effects was limited. For both SMA and CMAd, facilitation effects were more prevalent in distal than in proximal muscles. At an intensity of 60 µA, the mean latencies of M1 fac... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264681 Fri, 12 Feb 2010 06:01:54 +0100 3264681 http://www.medworm.com/index.php?rid=3264680&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F694%3Frss%3D1 People track facial expression dynamics with ease to accurately perceive distinct emotions. Although the superior temporal sulcus (STS) appears to possess mechanisms for perceiving changeable facial attributes such as expressions, the nature of the underlying neural computations is not known. Motivated by novel theoretical accounts, we hypothesized that visual and motor areas represent expressions as anticipated motion trajectories. Using magnetoencephalography, we show predictable transitions between fearful and neutral expressions (compared with scrambled and static presentations) heighten activity in visual cortex as quickly as 165 ms poststimulus onset and later (237 ms) engage fusiform gyrus, STS and premotor areas. Consistent with proposed models of biological motion representation, ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264680 Fri, 12 Feb 2010 06:01:54 +0100 3264680 http://www.medworm.com/index.php?rid=3264679&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F684%3Frss%3D1 Vesicular glutamate transporters 1 and 2 (VGLUT1, VGLUT2) show largely complementary distribution in the mature rodent brain and tend to segregate to synapses with different physiological properties. In the hippocampus, VGLUT1 is the dominate subtype in adult animals, whereas VGLUT2 is transiently expressed during early postnatal development. We generated and characterized VGLUT1 knockout mice in order to examine the functional contribution of this transporter to hippocampal synaptic plasticity and hippocampus-dependent spatial learning. Because complete deletion of VGLUT1 resulted in postnatal lethality, we used heterozygous animals for analysis. Here, we report that deletion of VGLUT1 resulted in impaired hippocampal long-term potentiation (LTP) in the CA1 region in vitro. In contrast, h... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264679 Fri, 12 Feb 2010 06:01:54 +0100 3264679 http://www.medworm.com/index.php?rid=3264678&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F672%3Frss%3D1 The relationship between cognition and a functional polymorphism in the catechol-O-methlytransferase (COMT) gene, val108/158met, is one of debate in the literature. Furthermore, based on the dopaminergic differences associated with the COMT val108/158met genotype, neural differences during cognition may be present, regardless of genotypic differences in cognitive performance. To investigate these issues the current study aimed to 1) examine the effects of COMT genotype using a large sample of healthy individuals (n = 496–1218) and multiple cognitive measures, and using a subset of the sample (n = 22), 2) examine whether COMT genotype effects medial temporal lobe (MTL) and frontal activity during successful relational memory processing, and 3) investigate group differences in function... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264678 Fri, 12 Feb 2010 06:01:54 +0100 3264678 http://www.medworm.com/index.php?rid=3264677&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F661%3Frss%3D1 Transforming Growth Factor β (Tgfβ) and associated signaling effectors are expressed in the forebrain, but little is known about the role of this multifunctional cytokine during forebrain development. Using hippocampal and cortical primary cell cultures of developing mouse brains, this study identified Tgfβ-regulated genes not only associated with cell cycle exit of progenitors but also with adoption of neuronal cell fate. Accordingly, we observed not only an antimitotic effect of Tgfβ on progenitors but also an increased expression of neuronal markers in Tgfβ treated cultures. This effect was dependent upon Smad4. Furthermore, in vivo loss-of-function analyses using Tgfβ2–/–/Tgfβ3–/– double mutant mice showed the opposite effect o... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264677 Fri, 12 Feb 2010 06:01:54 +0100 3264677 http://www.medworm.com/index.php?rid=3264676&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F650%3Frss%3D1 Experience-dependent plasticity of the adult visual cortex underlies perceptual learning and recovery of function following central nervous system lesions. To reveal the signal transduction cascades involved in adult cortical plasticity, we utilized a model of remapping of cortical topography following binocular retinal lesions. In this model, the lesion projection zone (LPZ) of primary visual cortex (V1) recovers visually driven activity by the sprouting of horizontal axonal connections originating from the cells in the surrounding region. To explore the molecular mechanism underlying this process, we used gene microarrays from an expression library prepared from Macaque V1. By microarray analysis of gene expression levels in the LPZ and the surrounding region, and subsequent confirmation... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264676 Fri, 12 Feb 2010 06:01:54 +0100 3264676 http://www.medworm.com/index.php?rid=3264675&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F641%3Frss%3D1 This event-related functional magnetic resonance imaging study compared neural correlates of executive function (cognitive set-shifting) in 28 healthy participants with either high (HIQ) or average (AIQ) intelligence. Despite comparable behavioral performance (except for slower reactions), the AIQ participants showed greater (especially prefrontal) activation during response selection; the HIQ participants showed greater activation (especially parietal) during feedback evaluation. HIQ participants appeared to engage cognitive resources to support more efficient strategies (planning during feedback in preparation for the upcoming response) which resulted in faster responses and less need for response inhibition and conflict resolution. Whether greater intelligence is associated with more or... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264675 Fri, 12 Feb 2010 06:01:54 +0100 3264675 http://www.medworm.com/index.php?rid=3264674&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F633%3Frss%3D1 In speech comprehension, the processing of auditory information and linguistic context are mutually dependent. This functional magnetic resonance imaging study examines how semantic expectancy ("cloze probability") in variably intelligible sentences ("noise vocoding") modulates the brain bases of comprehension. First, intelligibility-modulated activation along the superior temporal sulci (STS) was extended anteriorly and posteriorly in low-cloze sentences (e.g., "she weighs the flour") but restricted to a mid-superior temporal gyrus/STS area in more predictable high-cloze sentences (e.g., "she sifts the flour"). Second, the degree of left inferior frontal gyrus (IFG) (Brodmann's area 44) involvement in processing low-cloze constructions was proportional to increasing intelligibility. Left ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264674 Fri, 12 Feb 2010 06:01:54 +0100 3264674 http://www.medworm.com/index.php?rid=3264673&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F622%3Frss%3D1 Selective attention to speech versus nonspeech signals in complex auditory input could produce top-down modulation of cortical regions previously linked to perception of spoken, and even visual, words. To isolate such top-down attentional effects, we contrasted 2 equally challenging active listening tasks, performed on the same complex auditory stimuli (words overlaid with a series of 3 tones). Instructions required selectively attending to either the speech signals (in service of rhyme judgment) or the melodic signals (tone-triplet matching). Selective attention to speech, relative to attention to melody, was associated with blood oxygenation level–dependent (BOLD) increases during functional magnetic resonance imaging (fMRI) in left inferior frontal gyrus, temporal regions, and the... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264673 Fri, 12 Feb 2010 06:01:54 +0100 3264673 http://www.medworm.com/index.php?rid=3264672&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F612%3Frss%3D1 The amygdala is consistently implicated in biologically relevant learning tasks such as Pavlovian conditioning. In humans, the ability to identify individual faces based on the social outcomes they have predicted in the past constitutes a critical form of associative learning that can be likened to "social conditioning." To capture such learning in a laboratory setting, participants learned about faces that predicted negative, positive, or neutral social outcomes. Participants reported liking or disliking the faces in accordance with their learned social value. During acquisition, we observed differential functional magnetic resonance imaging activation across the human amygdaloid complex consistent with previous lesion, electrophysiological, and functional neuroimaging data. A region of t... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264672 Fri, 12 Feb 2010 06:01:54 +0100 3264672 http://www.medworm.com/index.php?rid=3264671&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F602%3Frss%3D1 We examined the spatial distribution of sulcal pits across the entire cortical region, and assessed the hemispheric asymmetry in their frequency and distribution in a large group of normal adult brains. We automatically extracted sulcal pits from magnetic resonance imaging data using surface-based methods and constructed a group map from 148 subjects. The spatial distribution of the sulcal pits was relatively invariant between individuals, showing high frequency and density in specific focal areas. The left and right sulcal pits were spatially covariant in the regions of the earliest developed sulci. The sulcal pits with great spatial invariance appear to be useful as stable anatomical landmarks. We showed the most significant asymmetry in the frequency and spatial variance of sulcal pits ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264671 Fri, 12 Feb 2010 06:01:53 +0100 3264671 http://www.medworm.com/index.php?rid=3264670&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F591%3Frss%3D1 In somatosensory cortex (S1) tactile stimulation activates specific regions. The borders between representations of different body parts constrain the spread of excitation and inhibition: connections that cross from one representation to another (cross-border, CB) are weaker than those remaining within the representation (noncross border, NCB). Thus, physiological properties of CB and NCB synapses onto layer 2/3 pyramidal neurons were compared using whole-cell recordings in layer 2/3 neurons close to the border between the forepaw and lower jaw representations. Electrical stimulation of CB and NCB connections was used to activate synaptic potentials. Properties of excitatory (EPSPs) and inhibitory (IPSPs) postsynaptic potentials (PSP) were determined using 3 methods: 1) minimal stimulation... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264670 Fri, 12 Feb 2010 06:01:53 +0100 3264670 http://www.medworm.com/index.php?rid=3264669&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F583%3Frss%3D1 In realistic auditory environments, people rely on both attentional control and attentional selection to extract intelligible signals from a cluttered background. We used functional magnetic resonance imaging to examine auditory attention to natural speech under such high processing-load conditions. Participants attended to a single talker in a group of 3, identified by the target talker's pitch or spatial location. A catch-trial design allowed us to distinguish activity due to top-down control of attention versus attentional selection of bottom-up information in both the spatial and spectral (pitch) feature domains. For attentional control, we found a left-dominant fronto-parietal network with a bias toward spatial processing in dorsal precentral sulcus and superior parietal lobule, and a... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264669 Fri, 12 Feb 2010 06:01:53 +0100 3264669 http://www.medworm.com/index.php?rid=3264668&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F570%3Frss%3D1 This study investigates how reading aloud modulates the neuronal interactions between visual recognition and articulatory areas, when both the putamen and thalamus are explicitly included. Using dynamic causal modeling in skilled readers who were reading regularly spelled English words, we compared 27 possible pathways that might connect the ventral anterior occipito-temporal sulcus (aOT) to articulatory areas in the precentral cortex (PrC). We focused on whether the neuronal interactions within these pathways were increased by reading relative to picture naming and other visual and articulatory control conditions. The results provide strong evidence that reading boosts the aOT–PrC pathway via the putamen but not the thalamus. However, the putamen pathway was not exclusive because th... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264668 Fri, 12 Feb 2010 06:01:53 +0100 3264668 http://www.medworm.com/index.php?rid=3264667&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F561%3Frss%3D1 Institutional rearing is associated with neurocognitive and behavioral difficulties. Although such difficulties are thought to reflect abnormal neurologic development resulting from early social deprivation (ED) and there is evidence for functional abnormality in children with histories of ED, the impact of early deprivation on brain anatomy has received little study in humans. The present study utilized an objective and sensitive neuroimaging analysis technique (Tract-Based Spatial Statistics) to evaluate white matter fractional anisotropy (FA) and diffusivity in a group of right-handed children with histories of ED (n = 17; mean age = 10.9 + 2.6 years) as compared with age-matched healthy controls (n = 15; mean age = 11.7 ± 2.8 years). Participants underwent magnetic resonance ima... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264667 Fri, 12 Feb 2010 06:01:53 +0100 3264667 http://www.medworm.com/index.php?rid=3264666&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F549%3Frss%3D1 We performed a resting-state functional connectivity study to investigate directly the functional correlations within the perisylvian language networks by seeding from 3 subregions of Broca's complex (pars opercularis, pars triangularis, and pars orbitalis) and their right hemisphere homologues. A clear topographical functional connectivity pattern in the left middle frontal, parietal, and temporal areas was revealed for the 3 left seeds. This is the first demonstration that a functional connectivity topology can be observed in the perisylvian language networks. The results support the assumption of the functional division for phonology, syntax, and semantics of Broca's complex as proposed by the memory, unification, and control (MUC) model and indicated a topographical functional organiza... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264666 Fri, 12 Feb 2010 06:01:53 +0100 3264666 http://www.medworm.com/index.php?rid=3264665&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F534%3Frss%3D1 The development of cortical gray matter, white matter (WM) volume, and WM microstructure in adolescence is beginning to be fairly well characterized by structural magnetic resonance imaging (sMRI) and diffusion tensor imaging (DTI) studies. However, these aspects of brain development have rarely been investigated concurrently in the same sample and hence the relations between them are not understood. We delineated the age-related changes in cortical thickness, regional WM volume, and diffusion characteristics and investigated the relationships between these properties of brain development. One hundred and sixty-eight healthy participants aged 8–30 years underwent sMRI and DTI. The results showed regional age-related cortical thinning, WM volume increases, and changes in diffusion par... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264665 Fri, 12 Feb 2010 06:01:53 +0100 3264665 http://www.medworm.com/index.php?rid=3264664&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F524%3Frss%3D1 The ability to draw analogies requires 2 key cognitive processes, relational integration and resolution of interference. The present study aimed to identify the neural correlates of both component processes of analogical reasoning within a single, nonverbal analogy task using event-related functional magnetic resonance imaging. Participants verified whether a visual analogy was true by considering either 1 or 3 relational dimensions. On half of the trials, there was an additional need to resolve interference in order to make a correct judgment. Increase in the number of dimensions to integrate was associated with increased activation in the lateral prefrontal cortex as well as lateral frontal pole in both hemispheres. When there was a need to resolve interference during reasoning, activati... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264664 Fri, 12 Feb 2010 06:01:53 +0100 3264664 http://www.medworm.com/index.php?rid=3264663&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F517%3Frss%3D1 The left parietal lobe has been proposed as a major language area. However, parietal cortical function is more usually considered in terms of the control of actions, contributing both to attention and cross-modal integration of external and reafferent sensory cues. We used positron emission tomography to study normal subjects while they overtly generated narratives, both spoken and written. The purpose was to identify the parietal contribution to the modality-specific sensorimotor control of communication, separate from amodal linguistic and memory processes involved in generating a narrative. The majority of left and right parietal activity was associated with the execution of writing under visual and somatosensory control irrespective of whether the output was a narrative or repetitive r... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264663 Fri, 12 Feb 2010 06:01:53 +0100 3264663 http://www.medworm.com/index.php?rid=3264662&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2F507%3Frss%3D1 Recent functional neuroimaging and brain lesion studies have implicated a network of left hemisphere regions in human tool use: 1) posterior middle temporal cortex involved in conceptual knowledge of tools, 2) posterior inferior parietal cortex for representations of learned tool use gestures, and 3) anterior inferior parietal cortex, along with posterior inferior frontal and ventral premotor cortices, involved in grasping and manipulating objects. Here, we use diffusion tensor imaging (DTI) to investigate the anatomical connections that support this putative network. DTI scans were acquired from nineteen right-handed males and a deterministic tractography algorithm was used to identify connections between these regions implicated in tool use. Three of the resulting pathways were larger in... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264662 Fri, 12 Feb 2010 06:01:53 +0100 3264662 http://www.medworm.com/index.php?rid=3264661&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2FNP-c%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264661 Fri, 12 Feb 2010 06:01:53 +0100 3264661 http://www.medworm.com/index.php?rid=3264660&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2FNP-b%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264660 Fri, 12 Feb 2010 06:01:52 +0100 3264660 http://www.medworm.com/index.php?rid=3264659&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2FNP-a%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264659 Fri, 12 Feb 2010 06:01:52 +0100 3264659 http://www.medworm.com/index.php?rid=3264658&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F3%2FNP%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3264658 Fri, 12 Feb 2010 06:01:52 +0100 3264658 http://www.medworm.com/index.php?rid=3154875&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F492%3Frss%3D1 Binaural cues are required for localization of sound sources. In the present paper, representation of binaural cues has been investigated in the adult auditory cortex. Hearing and congenitally deaf cats were stimulated through binaural cochlear implants and unit responses were collected in the subregion of field A1 showing the largest amplitudes of evoked local field potentials. Sensitivity to interaural time difference (ITD) in the range from –600 to 600 µs was tested at intensities of 0–10 dB above hearing threshold. Template ITD functions were fitted to the data and parameters of ITD functions were compared between deaf and hearing animals. In deaf animals, fewer units responded to binaural stimulation, and those that responded had smaller maximal evoked firing rate. T... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154875 Sat, 09 Jan 2010 00:03:00 +0100 3154875 http://www.medworm.com/index.php?rid=3154874&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F486%3Frss%3D1 The cerebellum has traditionally been viewed as a brain structure subserving skilled motor behaviors. However, the cerebellum might be involved not only in movement coordination, but also in action observation and understanding of others’ actions. Veridical visual perception of human body motion is of immense importance for a variety of daily-life situations and for successful social interactions. Here, by combining visual psychophysics with a lesion analysis, we assessed visual sensitivity to human walking in patients with lesions to the left cerebellum. Patients with left lateral cerebellar lesions exhibit deficits in visual sensitivity to body motion, whereas medial lesions do not substantially affect visual perception of human locomotion. The findings point to left lateral cerebe... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154874 Sat, 09 Jan 2010 00:03:00 +0100 3154874 http://www.medworm.com/index.php?rid=3154873&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F479%3Frss%3D1 Numerous functional neuroimaging studies have observed lateral parietal lobe activation during memory tasks: a surprise to clinicians who have traditionally associated the parietal lobe with spatial attention rather than memory. Recent neuropsychological studies examining episodic recollection after parietal lobe lesions have reported differing results. Performance was preserved in unilateral lesion patients on source memory tasks involving recollecting the context in which stimuli were encountered, and impaired in patients with bilateral parietal lesions on tasks assessing free recall of autobiographical memories. Here, we investigated a number of possible accounts for these differing results. In 3 experiments, patients with bilateral parietal lesions performed as well as controls at sour... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154873 Sat, 09 Jan 2010 00:03:00 +0100 3154873 http://www.medworm.com/index.php?rid=3154872&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F468%3Frss%3D1 The sensory–motor account of conceptual processing suggests that modality-specific attributes play a central role in the organization of object and action knowledge in the brain. An opposing view emphasizes the abstract, amodal, and symbolic character of concepts, which are thought to be represented outside the brain's sensory–motor systems. We conducted a functional magnetic resonance imaging study in which the participants listened to sentences describing hand/arm action events, visual events, or abstract behaviors. In comparison to visual and abstract sentences, areas associated with planning and control of hand movements, motion perception, and vision were activated when understanding sentences describing actions. Sensory–motor areas were activated to a greater extent... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154872 Sat, 09 Jan 2010 00:03:00 +0100 3154872 http://www.medworm.com/index.php?rid=3154871&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F456%3Frss%3D1 Fundamental brain functions depend on a balance between excitation (E) and inhibition (I) that is highly adjusted to a 20–80% set point in layer 5 pyramidal neurons (L5PNs) of rat visual cortex. Dysregulations of both the E–I balance and the serotonergic system in neocortical networks lead to serious neuronal diseases including depression, schizophrenia, and epilepsy. However, no link between the activation of neuronal 5-hydroxytryptamine receptors (5-HTRs) and the cortical E–I balance has yet been reported. Here we used a combination of patch-clamp recordings of composite stimulus-locked responses in L5PN following local electrical stimulations in either layer 2/3 or 6, simultaneous measurement of excitatory and inhibitory conductance dynamics, together with selective ph... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154871 Sat, 09 Jan 2010 00:03:00 +0100 3154871 http://www.medworm.com/index.php?rid=3154870&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F447%3Frss%3D1 Absolute pitch (AP) has been shown to be associated with morphological changes and neurophysiological adaptations in the planum temporale, a cortical area involved in higher-order auditory and speech perception processes. The direct link between speech processing and AP has hitherto not been addressed. We provide first evidence that AP compared with relative pitch (RP) ability is associated with significantly different hemodynamic responses to complex speech sounds. By systematically varying the lexical and/or prosodic information of speech stimuli, we demonstrated consistent activation differences in AP musicians compared with RP musicians and nonmusicians. These differences relate to stronger activations in the posterior part of the middle temporal gyrus and weaker activations in the ant... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154870 Sat, 09 Jan 2010 00:03:00 +0100 3154870 http://www.medworm.com/index.php?rid=3154869&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F433%3Frss%3D1 Real-life visual object recognition requires the processing of more than just geometric (shape, size, and orientation) properties. Surface properties such as color and texture are equally important, particularly for providing information about the material properties of objects. Recent neuroimaging research suggests that geometric and surface properties are dealt with separately within the lateral occipital cortex (LOC) and the collateral sulcus (CoS), respectively. Here we compared objects that differed either in aspect ratio or in surface texture only, keeping all other visual properties constant. Results on brain-intact participants confirmed that surface texture activates an area in the posterior CoS, quite distinct from the area activated by shape within LOC. We also tested 2 patients... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154869 Sat, 09 Jan 2010 00:03:00 +0100 3154869 http://www.medworm.com/index.php?rid=3154868&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F425%3Frss%3D1 Sensory stimulation resulting from one's own behavior or the outside world is easily differentiated by healthy persons who are able to predict the sensory consequences of their own actions. This ability has been related to cortical attenuation of activation elicited by self-produced stimulation. To date, however, the neural processes underlying this modulation remain to be elucidated. We therefore recorded whole-scalp magnetoencephalographic (MEG) signals from 10 young adults either when they were touched by another person with a brush or when they touched themselves with the same device. The main MEG responses peaked at the primary somatosensory cortex at 54 ± 2 ms. Signals and source strengths were about a fifth weaker to self-produced than external touch. Importantly, attenuation... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154868 Sat, 09 Jan 2010 00:03:00 +0100 3154868 http://www.medworm.com/index.php?rid=3154867&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F411%3Frss%3D1 Cortical-surface-based functional Magnetic Resonance Imaging mapping techniques and wide-field retinotopic stimulation were used to verify the presence of pattern motion sensitivity in human area V6. Area V6 is highly selective for coherently moving fields of dots, both at individual and group levels and even with a visual stimulus of standard size. This stimulus is a functional localizer for V6. The wide retinotopic stimuli used here also revealed a retinotopic map in the middle temporal cortex (area MT/V5) surrounded by several polar-angle maps that resemble the mosaic of small areas found around macaque MT/V5. Our results suggest that the MT complex (MT+) may be specialized for the analysis of motion signals, whereas area V6 may be more involved in distinguishing object and self-motion.... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154867 Sat, 09 Jan 2010 00:03:00 +0100 3154867 http://www.medworm.com/index.php?rid=3154866&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F404%3Frss%3D1 The ability to read the minds of others (i.e., to mentalize) requires that perceivers understand a wide range of different kinds of mental states, including not only others’ beliefs and knowledge but also their feelings, desires, and preferences. Moreover, although such inferences may occasionally rely on observable features of a situation, perceivers more typically mentalize under conditions of "uncertainty," in which they must generate plausible hypotheses about a target's mental state from ambiguous or otherwise underspecified information. Here, we use functional neuroimaging to dissociate the neural bases of these 2 distinct social–cognitive challenges: 1) mentalizing about different types of mental states (beliefs vs. preferences) and 2) mentalizing under conditions of var... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154866 Sat, 09 Jan 2010 00:03:00 +0100 3154866 http://www.medworm.com/index.php?rid=3154865&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F393%3Frss%3D1 To delineate the cellular mechanisms underlying the function of medial prefrontal cortex (mPFC) networks, it is critical to understand how synaptic inputs from various afferents are integrated and drive neuronal activity in this region. Using a newly developed slice preparation, we were able to identify a bundle of axons that contain extraneocortical fibers projecting to neurons in the prelimbic cortex. The anatomical origin and functional connectivity of the identified fiber bundle were probed by in vivo track tracing in combination with optic and whole-cell recordings of neurons in layers 2/3 and 5/6. We demonstrate that the identified bundle contains afferent fibers primarily from the ventral hippocampus but does not include contributions from the mediodorsal nucleus of the thalamus, am... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154865 Sat, 09 Jan 2010 00:03:00 +0100 3154865 http://www.medworm.com/index.php?rid=3154864&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F383%3Frss%3D1 To comprehend emotional prosodic cues in speech is a critical function of human social life. However, it is common in everyday communication that conflicting information in emotional prosody and semantic content co-occur. Here, we sought to specify brain regions involved in conflict monitoring of these interfering communication channels. By means of functional magnetic resonance imaging, we obtained signal increases in the right dorsal anterior cingulate cortex and right superior temporal gyrus (STG) and superior temporal sulcus when participants listened to incongruous compared with congruous sentences. Moreover, valence-specific effects were found in the left inferior frontal gyrus and left STG for happily intoned sentences expressing a negative content. The left caudate nucleus along wi... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154864 Sat, 09 Jan 2010 00:03:00 +0100 3154864 http://www.medworm.com/index.php?rid=3154863&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F365%3Frss%3D1 We investigated the relationship between visual experience and temporal intervals of synchronized brain activity. Using high-density scalp electroencephalography, we examined how synchronized activity depends on visual stimulus information and on individual observer sensitivity. In a perceptual grouping task, we varied the ambiguity of visual stimuli and estimated observer sensitivity to this variation. We found that durations of synchronized activity in the beta frequency band were associated with both stimulus ambiguity and sensitivity: the lower the stimulus ambiguity and the higher individual observer sensitivity the longer were the episodes of synchronized activity. Durations of synchronized activity intervals followed an extreme value distribution, indicating that they were limited b... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154863 Sat, 09 Jan 2010 00:03:00 +0100 3154863 http://www.medworm.com/index.php?rid=3154862&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F352%3Frss%3D1 Although widespread neural atrophy is an inevitable consequence of normal aging, not all cognitive abilities decline as we age. For example, spoken language comprehension tends to be preserved, despite atrophy in neural regions involved in language function. Here, we combined measures of behavior, functional activation, and gray matter (GM) change in a younger (19–34 years) and older group (49–86 years) of participants to identify the mechanisms leading to preserved language comprehension across the adult life span. We focussed primarily on syntactic functions because these are strongly left lateralized, providing the potential for contralateral recruitment. In an functional magnetic resonance imaging study, we used a word-monitoring task to minimize working memory demands, man... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154862 Sat, 09 Jan 2010 00:03:00 +0100 3154862 http://www.medworm.com/index.php?rid=3154861&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F339%3Frss%3D1 Some animals are forced to rely more on non-visual signals, such as audition or olfaction, than on vision when a bright environment becomes dark. By recording from a primary-like auditory cortex (field A) in freely moving guinea pigs, possible changes in the responsiveness of single units were explored in association with illumination changes. For a subset of units, we found that robust decreases (off-decrease) or increases (off-increase) in baseline discharge (BsD) were initiated soon after room light was silently extinguished. These neuronal changes were accompanied by the initiation of explorative locomotion, possibly reflecting a changed internal brain state. Preferred acoustic stimuli evoked salient excitatory responses against the reduced BsD level in the dark for the off-decrease un... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154861 Sat, 09 Jan 2010 00:03:00 +0100 3154861 http://www.medworm.com/index.php?rid=3154860&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F328%3Frss%3D1 In this study, we combine TMS, functional magnetic resonance imaging, and calculation of the induced electric field to study the neural correlates of visual suppression. For parafoveal visual stimulation in the lower right half of the visual field, area V2d is shown to be the likely TMS target based on its anatomical location close to the skull surface. Furthermore, isolated stimulation of area V3 also results in robust visual suppression. Notably, V3 stimulation does not directly affect the feedback from higher visual areas that is relayed mainly via V2 to V1. These findings support the view that intact activity patterns in several early visual areas (rather than merely in V1) are likewise important for the perception of the stimulus. (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154860 Sat, 09 Jan 2010 00:03:00 +0100 3154860 http://www.medworm.com/index.php?rid=3154859&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F315%3Frss%3D1 The relationship between orthography (spelling) and phonology (speech sounds) varies across alphabetic languages. Consequently, learning to read a second alphabetic language, that uses the same letters as the first, increases the phonological associations that can be linked to the same orthographic units. In subjects with English as their first language, previous functional imaging studies have reported increased left ventral prefrontal activation for reading words with spellings that are inconsistent with their orthographic neighbors (e.g., PINT) compared with words that are consistent with their orthographic neighbors (e.g., SHIP). Here, using functional magnetic resonance imaging (fMRI) in 17 Italian–English and 13 English–Italian bilinguals, we demonstrate that left ventral... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154859 Sat, 09 Jan 2010 00:03:00 +0100 3154859 http://www.medworm.com/index.php?rid=3154858&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F304%3Frss%3D1 During embryonic cortical development, expression of Tis21 is associated with cell cycle lengthening and neurogenic divisions of progenitor cells. We here investigated if the expression pattern of Tis21 also correlates with the generation of new neurons in the adult hippocampus. We used Tis21 knock-in mice expressing green fluorescent protein (GFP) and studied Tis21-GFP expression together with markers of adult hippocampal neurogenesis in newly generated cells. We found that Tis21-GFP 1) was absent from the radial glia–like putative stem cells (type-1 cells), 2) first appeared in transient amplifying progenitor cells (type-2 and 3 cells), 3) did not colocalize with markers of early postmitotic maturation stage, 4) was expressed again in maturing neurons, and 5) finally decreased in m... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154858 Sat, 09 Jan 2010 00:03:00 +0100 3154858 http://www.medworm.com/index.php?rid=3154857&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F294%3Frss%3D1 The parahippocampal place area (PPA) is a region of human cortex that responds more strongly to visual scenes (e.g., landscapes or cityscapes) than to other visual stimuli. It has been proposed that the primary function of the PPA is encoding of contextual information about object co-occurrence. Supporting this context hypothesis are reports that the PPA responds more strongly to strong-context than to weak-context objects and more strongly to famous faces (for which contextual associations are available) than to nonfamous faces. We reexamined the reliability of these 2 effects by scanning subjects with functional magnetic resonance imaging while they viewed strong- and weak-context objects, scrambled versions of these objects, and famous and nonfamous faces. "Contextual" effects for objec... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154857 Sat, 09 Jan 2010 00:03:00 +0100 3154857 http://www.medworm.com/index.php?rid=3154856&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F282%3Frss%3D1 To examine the generality of cholinergic involvement in visual memory in primates, we trained macaque monkeys either on an object-in-place scene learning task or in delayed nonmatching-to-sample (DNMS). Each monkey received either selective cholinergic depletion of inferotemporal cortex (including the entorhinal cortex and perirhinal cortex) with injections of the immunotoxin ME20.4-saporin or saline injections as a control and was postoperatively retested. Cholinergic depletion of inferotemporal cortex was without effect on either task. Each monkey then received fornix transection because previous studies have shown that multiple disconnections of temporal cortex can produce synergistic impairments in memory. Fornix transection mildly impaired scene learning in monkeys that had received s... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154856 Sat, 09 Jan 2010 00:03:00 +0100 3154856 http://www.medworm.com/index.php?rid=3154855&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F271%3Frss%3D1 Cognitive control is an inherently multivariate phenomenon, and its neural basis is currently unclear. Here we examined using functional magnetic resonance imaging how participants retrieve prelearnt information from memory, use this information to guide responses for an impending decision, and adjust their responses based on outcome feedback. We developed a behavioral task designed to manipulate memory outcome–retrieval load, outcome-anticipation interval, and outcome-feedback processes. This allowed us to understand the neural basis of these cognitive processes in isolation and how they interact. Extending previous work, we found a retrieval-load by outcome-feedback interaction in the left globus pallidus; an outcome-feedback by anticipation-interval interaction in the inferior pre... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154855 Sat, 09 Jan 2010 00:03:00 +0100 3154855 http://www.medworm.com/index.php?rid=3154854&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2F257%3Frss%3D1 To investigate the fine anatomical organization of cortical inputs to visual association area TE, 2–3 small injections of retrograde tracers were made in macaque monkeys. Injections were made as a terminal procedure, after optical imaging and electrophysiological recording, and targeted to patches physiologically identified as object-selective. Retrogradely labeled neurons occurred in several unimodal visual areas, the superior temporal sulcus, intraparietal sulcus (IPS), and prefrontal cortex (PFC), consistent with previous studies. Despite the small injection size (<0.5 mm wide), the projection foci in visual areas, but not in IPS or PFC, were spatially widespread (4–6 mm in extent), and predominantly consisted of neurons labeled by only one of the injections. This can be ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154854 Sat, 09 Jan 2010 00:03:00 +0100 3154854 http://www.medworm.com/index.php?rid=3154853&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2FNP-c%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154853 Sat, 09 Jan 2010 00:03:00 +0100 3154853 http://www.medworm.com/index.php?rid=3154852&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2FNP-b%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154852 Sat, 09 Jan 2010 00:03:00 +0100 3154852 http://www.medworm.com/index.php?rid=3154851&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2FNP-a%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154851 Sat, 09 Jan 2010 00:03:00 +0100 3154851 http://www.medworm.com/index.php?rid=3154850&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F2%2FNP%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3154850 Sat, 09 Jan 2010 00:03:00 +0100 3154850 http://www.medworm.com/index.php?rid=3081052&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F254%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081052 Fri, 11 Dec 2009 18:07:51 +0100 3081052 http://www.medworm.com/index.php?rid=3081051&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F253%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081051 Fri, 11 Dec 2009 18:07:50 +0100 3081051 http://www.medworm.com/index.php?rid=3081050&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F241%3Frss%3D1 Visuomotor transformation is a fundamental process in executing voluntary actions. The final steps of this transformation are presumed to take place in the corticospinal (CS) system, yet the way in which the motor cortex (MC) interacts with spinal circuitry during this process is unclear. We studied neural correlates of visuomotor transformation in the MC and cervical spinal cord while monkeys performed an isometric wrist task. We recorded 2 measures of population activity: local field potential (LFP), reflecting local synaptic inputs and multi-unit activity (MUA), reflecting spiking activity emitted by nearby neurons. We found robust cortical and spinal responses locked to visual and motor events. In motor cortex, LFP responses were predominantly visually related; MUA responses were mostl... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081050 Fri, 11 Dec 2009 18:07:50 +0100 3081050 http://www.medworm.com/index.php?rid=3081049&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F229%3Frss%3D1 Apical dendritic bundles from pyramidal neurons are a prominent feature of cortical neuropil but with significant area specializations. Here, we investigate mechanisms of bundle formation, focusing on layer (L) 2 bundles in rat granular retrosplenial cortex (GRS), a limbic area implicated in spatial memory. By using microarrays, we first searched for genes highly and specifically expressed in GRS L2 at postnatal day (P) 3 versus GRS L2 at P12 (respectively, before and after bundle formation), versus GRS L5 (at P3), and versus L2 in barrel field cortex (BF) (at P3). Several genes, including neurotrophin-3 (NT-3), were identified as transiently and specifically expressed in GRS L2. Three of these were cloned and confirmed by in situ hybridization. To test that NT-3–mediated events are ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081049 Fri, 11 Dec 2009 18:07:50 +0100 3081049 http://www.medworm.com/index.php?rid=3081048&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F214%3Frss%3D1 Using retrograde transneuronal transfer of rabies virus in combination with a conventional tracer (cholera toxin B), we studied simultaneously direct (thalamocortical) and polysynaptic inputs to the ventral lateral intraparietal area (LIPv) and the medial intraparietal area (MIP) in nonhuman primates. We found that these areas receive major disynaptic inputs from specific portions of the cerebellar nuclei, the ventral dentate (D), and ventrolateral interpositus posterior (IP). Area LIPv receives inputs from oculomotor domains of the caudal D and IP. Area MIP is the target of projections from the ventral D (mainly middle third), and gaze- and arm-related domains of IP involved in reaching and arm/eye/head coordination. We also showed that cerebellar cortical "output channels" to MIP predomi... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081048 Fri, 11 Dec 2009 18:07:50 +0100 3081048 http://www.medworm.com/index.php?rid=3081047&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F205%3Frss%3D1 Recent neuroimaging studies have indicated a predominant role of the anterior prefrontal cortex (aPFC) in deception and moral cognition, yet the functional contribution of the aPFC to deceptive behavior remains unknown. We hypothesized that modulating the excitability of the aPFC by transcranial direct current stimulation (tDCS) could reveal its functional contribution in generating deceitful responses. Forty-four healthy volunteers participated in a thief role-play in which they were supposed to steal money and then to attend an interrogation with the Guilty Knowledge Test. During the interrogation, participants received cathodal, anodal, or sham tDCS. Remarkably, inhibition of the aPFC by cathodal tDCS did not lead to an impairment of deceptive behavior but rather to a significant improv... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081047 Fri, 11 Dec 2009 18:07:50 +0100 3081047 http://www.medworm.com/index.php?rid=3081046&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F198%3Frss%3D1 Functional imaging studies have revealed roles for orbitofrontal cortex (OFC) in reward processing and decision making. In many situations, rewards signal that the current behavior should be maintained, whereas punishments cue a change in behavior. Thus, hedonic responses to reinforcers are conflated with their function as behavioral cues. In an attempt to disambiguate these functions, we performed a functional magnetic resonance imaging study of a 2-choice decision-making task. After each trial, subjects were rewarded or punished and independently provided with a cue to maintain or change behavior. We identified key regions of OFC involved in these processes. An anterior medial focus responded to reward, whereas bilateral lateral foci responded to punishment. The right-sided lateral regio... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081046 Fri, 11 Dec 2009 18:07:50 +0100 3081046 http://www.medworm.com/index.php?rid=3081045&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F187%3Frss%3D1 We examined the neural signatures of stimulus features in visual working memory (WM) by integrating functional magnetic resonance imaging (fMRI) and event-related potential data recorded during mental manipulation of colors, rotation angles, and color–angle conjunctions. The N200, negative slow wave, and P3b were modulated by the information content of WM, and an fMRI-constrained source model revealed a progression in neural activity from posterior visual areas to higher order areas in the ventral and dorsal processing streams. Color processing was associated with activity in inferior frontal gyrus during encoding and retrieval, whereas angle processing involved right parietal regions during the delay interval. WM for color–angle conjunctions did not involve any additional neur... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081045 Fri, 11 Dec 2009 18:07:50 +0100 3081045 http://www.medworm.com/index.php?rid=3081044&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F169%3Frss%3D1 Motor output capabilities of the forelimb representation of dorsal motor area (PMd) and ventral motor area (PMv) were compared with primary motor cortex (M1) in terms of latency, strength, sign, and distribution of effects. Stimulus-triggered averages (60 µA) of electromyographic activity collected from 24 forelimb muscles were computed at 314 tracks in 2 monkeys trained to perform a reach-to-grasp task. The onset latency and magnitude of facilitation effects from PMd and PMv were significantly longer and 7- to 9-fold weaker than those from M1. Proximal muscles were predominantly represented in PMd and PMv. A joint-dependent flexor or extensor preference was also present. Distal and proximal muscle representations were intermingled in PMd and PMv. A gradual increase in latency and de... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081044 Fri, 11 Dec 2009 18:07:50 +0100 3081044 http://www.medworm.com/index.php?rid=3081043&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F141%3Frss%3D1 We have found that the 2 architectonic subdivisions of the prefrontal area 45, 45A and 45B, display connectivity patterns that clearly distinguish them from one another and from their neighboring architectonic areas. Area 45A is primarily connected to the frontal areas 45B, 12l, caudal 12r, 12o, 10, rostrodorsal 46, 9/8B, 44, 8/FEF (frontal eye field), and the SEF (supplementary eye field), temporal area IPa, and unique among all the studied areas, to the superior temporal polysensory (STP) area and auditory parabelt areas. Area 45B displayed much stronger frontal connections with the oculomotor areas 8/FEF, 8r, and the SEF than those of area 45A, primary connections with areas 12l, caudal 12r, 12o, and 8B, and unlike area 45A, with areas ventrorostral 46, rostral 12r, 12m, and 13m. Tempor... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081043 Fri, 11 Dec 2009 18:07:50 +0100 3081043 http://www.medworm.com/index.php?rid=3081042&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F130%3Frss%3D1 Making conclusions about the functional neuroanatomical organization of the human brain requires methods for relating the functional anatomy of an individual's brain to population variability. We have developed a method for aligning the functional neuroanatomy of individual brains based on the patterns of neural activity that are elicited by viewing a movie. Instead of basing alignment on functionally defined areas, whose location is defined as the center of mass or the local maximum response, the alignment is based on patterns of response as they are distributed spatially both within and across cortical areas. The method is implemented in the two-dimensional manifold of an inflated, spherical cortical surface. The method, although developed using movie data, generalizes successfully to da... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081042 Fri, 11 Dec 2009 18:07:50 +0100 3081042 http://www.medworm.com/index.php?rid=3081041&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F121%3Frss%3D1 In the present study, we identified the most probable trajectories of point-to-point segregated connections between functional attentional centers using a combination of functional magnetic resonance imaging and a novel diffusion tensor imaging–based algorithm for pathway extraction. Cortical regions activated by a visuospatial attention task were subsequently used as seeds for probabilistic fiber tracking in 26 healthy subjects. Combining probability maps of frontal and temporoparietal regions yielded a network that consisted of dorsal and ventral connections. The dorsal connections linked temporoparietal cortex with the frontal eye field and area 44 of the inferior frontal gyrus (IFG). Traveling along superior longitudinal and arcuate fascicles, these fibers are well described in r... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081041 Fri, 11 Dec 2009 18:07:50 +0100 3081041 http://www.medworm.com/index.php?rid=3081040&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F109%3Frss%3D1 We presented multiple exemplars of semantically congruent multisensory objects (e.g., dogs with barks) and semantically incongruent multisensory objects (e.g., guitars with barks) while recording high-density event-related potentials and tested whether highly learned associations among the multisensory features of well-known objects modulated the spread of attention from an attended visual stimulus to its paired, task-irrelevant sound. Our findings distinguish dual mechanisms for the cross-sensory spread of attention: 1) a stimulus-driven spread of attention that occurs whenever a task-irrelevant sound is simultaneously presented with an attended visual stimulus, independent of highly learned associations, and 2) a representation-driven spread of attention that occurs in response to a task... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081040 Fri, 11 Dec 2009 18:07:50 +0100 3081040 http://www.medworm.com/index.php?rid=3081039&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F89%3Frss%3D1 In prairie voles, primary sensory areas are dominated by neurons that respond to one sensory modality, but some neurons also respond to stimulation of other modalities. To reveal the anatomical substrate for these multimodal responses, we examined the connections of the primary auditory area + the anterior auditory field (A1 + AAF), the temporal anterior area (TA), and the primary visual area (V1). A1 + AAF had intrinsic connections and connections with TA, multimodal cortex (MM), V1, and primary somatosensory area (S1). TA had intrinsic connections and connections with A1 + AAF, MM, and V2. Callosal connections were observed in homotopic locations in auditory cortex for both fields. A1 + AAF and TA receive thalamic input primarily from divisions of the medial geniculate nucleus but also f... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081039 Fri, 11 Dec 2009 18:07:50 +0100 3081039 http://www.medworm.com/index.php?rid=3081038&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F77%3Frss%3D1 Numerous studies have identified the intraparietal sulcus (IPS) as an area critically involved in numerical processing. IPS neurons in macaques are tuned to a preferred numerosity, hence neurally coding numerosity in a number-selective way. Neuroimaging studies in humans have demonstrated number-selective processing in the anterior parts of the IPS. Nevertheless, the processes that convert visual input into a number-selective neural code remain unknown. Computational studies have suggested that a neural coding stage that is sensitive, but not selective to number, precedes number-selective coding when processing nonsymbolic quantities but not when processing symbolic quantities. In Experiment 1, we used functional magnetic resonance imaging to localize number-sensitive areas in the human br... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081038 Fri, 11 Dec 2009 18:07:50 +0100 3081038 http://www.medworm.com/index.php?rid=3081037&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F70%3Frss%3D1 Solving problems often requires seeing new connections between concepts or events that seemed unrelated at first. Innovative solutions of this kind depend on analogical reasoning, a relational reasoning process that involves mapping similarities between concepts. Brain-based evidence has implicated the frontal pole of the brain as important for analogical mapping. Separately, cognitive research has identified semantic distance as a key characteristic of the kind of analogical mapping that can support innovation (i.e., identifying similarities across greater semantic distance reveals connections that support more innovative solutions and models). However, the neural substrates of semantically distant analogical mapping are not well understood. Here, we used functional magnetic resonance ima... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081037 Fri, 11 Dec 2009 18:07:50 +0100 3081037 http://www.medworm.com/index.php?rid=3081036&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F61%3Frss%3D1 This study supports the hypothesis that adolescents are hypersensitive to reward and adds to the current literature in demonstrating that neural activation differs in adolescents even for small rewards in the absence of choice. These findings may have important implications for understanding adolescent risk-taking behavior. (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081036 Fri, 11 Dec 2009 18:07:50 +0100 3081036 http://www.medworm.com/index.php?rid=3081035&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F46%3Frss%3D1 There has been evidence for functional abnormalities of the verbal working memory system in schizophrenia. Verbal working memory crucially involves the interplay between the anterior and posterior language systems, and previous studies have shown converging evidence for abnormalities in the posterior language system in schizophrenia. In this functional magnetic resonance imaging study, we measured cortical activity in chronic schizophrenic patients and matched healthy controls during auditory and visual verbal working memory tasks. We employed 1) regional analyses specifically targeting the posterior language system and 2) analyses of functional connectivity between anterior and posterior language regions. We performed these analyses separately for each memory stage and modality. In the re... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081035 Fri, 11 Dec 2009 18:07:50 +0100 3081035 http://www.medworm.com/index.php?rid=3081034&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F34%3Frss%3D1 Performance of a unimanual motor task often induces involuntary mirror electromyographic (EMG) activity in the opposite, resting hand. In spite of the ubiquitous presence of mirroring, little is known regarding the underlying cortical contributions. Here, we used functional magnetic resonance imaging (fMRI) to study brain regions activated in association with parametric increases in right isometric wrist flexion force (10%, 20%, 30%, and 70%) in 12 healthy volunteers. During scanning, EMG activity was recorded bilaterally from flexor carpi radialis (FCR), extensor carpi radialis (ECR), biceps brachii (BB), and triceps brachii (TB). Mirror EMG was observed in left FCR during 20%, 30%, and 70% of force. Left ECR, BB, and TB showed mirror EMG only at 70% of force. Increasing force was associa... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081034 Fri, 11 Dec 2009 18:07:50 +0100 3081034 http://www.medworm.com/index.php?rid=3081033&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F25%3Frss%3D1 We employed a sulcal geometry–based approach to investigate the morphology of the central sulcus (CS) in musicians (pianists). The anterior and posterior walls of the CS were first manually outlined from high-resolution magnetic resonance (MR) images of 41 right-handed subjects (20 musicians and 21 controls), followed by a surface reconstruction and parameterization procedure to ensure the anatomical correspondence of surface locations across subjects. The intrasulcal length, surface area, and local variability of the CS were measured. There were no significant differences in either the intrasulcal length or surface area of the anterior or posterior walls between the 2 groups. However, we observed that the controls had a pronounced left-larger-than-right asymmetry that was reduced in... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081033 Fri, 11 Dec 2009 18:07:50 +0100 3081033 http://www.medworm.com/index.php?rid=3081032&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F13%3Frss%3D1 The pathway from cortical layer 6 to the thalamus is a property of all thalamic relay nuclei. This pathway, as a population, directly excites relay cells and indirectly inhibits them via the thalamic reticular nucleus. To understand the circuit organization of this cortical feedback, we used laser-scanning photostimulation, which specifically activates somata or dendrites, to stimulate the primary somatosensory cortex in an in vitro thalamocortical slice preparation while recording from neurons of the ventral posterior medial nucleus. Layer 6 photostimulation evoked biphasic excitatory postsynaptic current/inhibitory postsynaptic current (EPSC/IPSC) responses in the neurons of the ventral posterior medial nucleus, indicating that such photostimulation strongly activates reticular cells. Th... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081032 Fri, 11 Dec 2009 18:07:49 +0100 3081032 http://www.medworm.com/index.php?rid=3081031&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2F1%3Frss%3D1 In order for stimuli to be perceptually discriminable, their representations in the brain must be distinct. Investigating the task of discriminating the syllables /ra/ and /la/, we hypothesized that the more distinct a person's neural representations of those sounds were, the better their behavioral ability to discriminate them would be. Standard neuroimaging approaches are ill-suited to testing this hypothesis as they have problems differentiating between neural representations spatially intermingled within the same brain area. We therefore performed multi-voxel pattern-based analysis of the functional magnetic resonance imaging (fMRI) activity elicited by these syllables, in native speakers of English and Japanese. In right primary auditory cortex, the statistical separability of these f... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081031 Fri, 11 Dec 2009 18:07:49 +0100 3081031 http://www.medworm.com/index.php?rid=3081030&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2FNP-c%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081030 Fri, 11 Dec 2009 18:07:49 +0100 3081030 http://www.medworm.com/index.php?rid=3081029&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2FNP-b%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081029 Fri, 11 Dec 2009 18:07:49 +0100 3081029 http://www.medworm.com/index.php?rid=3081028&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2FNP-a%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081028 Fri, 11 Dec 2009 18:07:49 +0100 3081028 http://www.medworm.com/index.php?rid=3081027&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F20%2F1%2FNP%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=3081027 Fri, 11 Dec 2009 18:07:49 +0100 3081027 http://www.medworm.com/index.php?rid=2969032&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F3030%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969032 Sat, 07 Nov 2009 01:37:07 +0100 2969032 http://www.medworm.com/index.php?rid=2969031&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F3011%3Frss%3D1 -Aminobutyric acid (GABA)–releasing inhibitory interneurons, a critical component of cortical circuitry, are involved in myriad known functional roles. However, information regarding the cytoarchitectural, physiological, and molecular properties of interneurons in posterior piriform cortex (PPC) is sparse. Taking advantage of the glutamic acid decarboxylase (GAD)67–enhanced green fluorescent protein (EGFP) mouse, we used in vitro whole-cell patch-clamp techniques to record from GABAergic interneurons across all 3 layers of PPC and, subsequently, to reconstruct their morphology. For the first time, 5 groups of interneurons are identified, whose firing types are defined based on those described within neocortex. Interestingly, each interneuron group with a distinct firing type al... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969031 Sat, 07 Nov 2009 01:37:07 +0100 2969031 http://www.medworm.com/index.php?rid=2969030&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F3001%3Frss%3D1 Neural connectivity at the cellular and mesoscopic level appears very specific and is presumed to arise from highly specific developmental mechanisms. However, there are general shared features of connectivity in systems as different as the networks formed by individual neurons in Caenorhabditis elegans or in rat visual cortex and the mesoscopic circuitry of cortical areas in the mouse, macaque, and human brain. In all these systems, connection length distributions have very similar shapes, with an initial large peak and a long flat tail representing the admixture of long-distance connections to mostly short-distance connections. Furthermore, not all potentially possible synapses are formed, and only a fraction of axons (called filling fraction) establish synapses with spatially neighborin... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969030 Sat, 07 Nov 2009 01:37:07 +0100 2969030 http://www.medworm.com/index.php?rid=2969029&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2993%3Frss%3D1 By virtue of its widespread afferent projections, perirhinal cortex is thought to bind polymodal information into abstract object-level representations. Consistent with this proposal, deficits in cross-modal integration have been reported after perirhinal lesions in nonhuman primates. It is therefore surprising that imaging studies of humans have not observed perirhinal activation during visual–tactile object matching. Critically, however, these studies did not differentiate between congruent and incongruent trials. This is important because successful integration can only occur when polymodal information indicates a single object (congruent) rather than different objects (incongruent). We scanned neurologically intact individuals using functional magnetic resonance imaging (fMRI) wh... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969029 Sat, 07 Nov 2009 01:37:07 +0100 2969029 http://www.medworm.com/index.php?rid=2969028&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2982%3Frss%3D1 In conclusion, alterations in activity reporter gene expression throughout area 17 contribute to the lesion-induced functional reorganization. (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969028 Sat, 07 Nov 2009 01:37:07 +0100 2969028 http://www.medworm.com/index.php?rid=2969027&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2970%3Frss%3D1 Previous studies have proposed a variety of mechanisms by which attention influences neuronal activity. Here we investigated the mechanisms of attention in the striate cortex of monkeys performing a spatial or an object-based attention task at various stimulus contrasts and compared neuronal contrast response functions with and without attention. Our data are best described by an "additive" interaction: The influence of attention on the neuronal response is relatively independent of the stimulus contrast, at least when the stimulus has enough contrast to become visible. This shows that attention adds to the neuronal responses in a largely contrast invariant manner. These data support recent functional magnetic resonance imaging studies and suggest that feedback from higher areas exerts a c... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969027 Sat, 07 Nov 2009 01:37:07 +0100 2969027 http://www.medworm.com/index.php?rid=2969026&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2959%3Frss%3D1 Spike timing–dependent plasticity (STDP) is a strong candidate for an N-methyl-D-aspartate (NMDA) receptor-dependent form of synaptic plasticity that could underlie the development of receptive field properties in sensory neocortices. Whilst induction of timing-dependent long-term potentiation (t-LTP) requires postsynaptic NMDA receptors, timing-dependent long-term depression (t-LTD) requires the activation of presynaptic NMDA receptors at layer 4-to-layer 2/3 synapses in barrel cortex. Here we investigated the developmental profile of t-LTD at layer 4-to-layer 2/3 synapses of mouse barrel cortex and studied their NMDA receptor subunit dependence. Timing-dependent LTD emerged in the first postnatal week, was present during the second week and disappeared in the adult, whereas t-LTP p... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969026 Sat, 07 Nov 2009 01:37:07 +0100 2969026 http://www.medworm.com/index.php?rid=2969025&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2946%3Frss%3D1 We used functional magnetic resonance imaging (fMRI) to investigate the brain basis of overt and covert forms of attention during search, while employing stringent control of both eye movements and attentional shifts. A factorial design compared overt and covert forms of goal-directed serial search versus stimulus-driven tracking. To match ocular changes and the number and magnitude of attention shifts across cells in the design, stimulus-driven tracking involved trial-specific "replay" of previous goal-directed eye movements. We found that, in terms of cortical activations, engagement of the dorsal fronto-parietal network by goal-directed attention did not depend on oculomotor requirements, being found similarly for covert attention, in accord with other work. However, analyses of effecti... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969025 Sat, 07 Nov 2009 01:37:07 +0100 2969025 http://www.medworm.com/index.php?rid=2969024&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2930%3Frss%3D1 Although the inferior parietal cortex (IPC) has been consistently implicated in mathematical cognition, the functional roles of its subdivisions are poorly understood. We address this problem using probabilistic cytoarchitectonic maps of IPC subdivisions intraparietal sulcus (IPS), angular gyrus (AG), and supramarginal gyrus. We quantified IPC responses relative to task difficulty and individual differences in task proficiency during mental arithmetic (MA) tasks performed with Arabic (MA-A) and Roman (MA-R) numerals. The 2 tasks showed similar levels of activation in 3 distinct IPS areas, hIP1, hIP2, and hIP3, suggesting their obligatory role in MA. Both AG areas, PGa and PGp, were strongly deactivated in both tasks, with stronger deactivations in posterior area PGp. Compared with the more... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969024 Sat, 07 Nov 2009 01:37:07 +0100 2969024 http://www.medworm.com/index.php?rid=2969023&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2916%3Frss%3D1 The morphology of axonal and dendritic arbors in the immature cerebral cortex influences the degree of anisotropy in water diffusion. This enables cortical maturation to be monitored by the noninvasive technique of diffusion tensor magnetic resonance imaging (DTI). Herein, we utilized DTI of postmortem ferret brain to quantify regional and temporal patterns in cortical maturation. We found that diffusion anisotropy within the isocortex decreases over the first month of life, coinciding closely in time with expansion of axonal and dendritic cellular processes of pyramidal neurons. Regional patterns consist of differences between allocortex and isocortex, a regional anisotropy gradient that closely parallels the transverse neurogenetic gradient, and differences between primary and nonprimary... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969023 Sat, 07 Nov 2009 01:37:07 +0100 2969023 http://www.medworm.com/index.php?rid=2969022&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2902%3Frss%3D1 Corticofugal projections to the thalamus reveal 2 axonal morphologies, each associated with specific physiological attributes. These determine the functional characteristics of thalamic neurons. It is not clear, however, whether such features characterize the corticofugal projections that mediate multisensory integration in superior colliculus (SC) neurons. The cortico-collicular projections from cat anterior ectosylvian sulcus (AES) are derived from its visual, auditory, and somatosensory representations and are critical for multisensory integration. Following tracer injections into each subdivision, 2 types of cortico-collicular axons were observed. Most were categorized as type I and consisted of small-caliber axons traversing long distances without branching, bearing mainly small bouto... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969022 Sat, 07 Nov 2009 01:37:07 +0100 2969022 http://www.medworm.com/index.php?rid=2969021&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2891%3Frss%3D1 Preterm birth results in significant neurodevelopmental disability. A neonatal rodent model of chronic sublethal hypoxia (CSH), which mimics effects of preterm birth, was used to characterize neurodevelopmental consequences of prolonged exposure to hypoxia using tissue anisotropy measurements from diffusion tensor imaging. Corpus callosum, cingulum, and fimbria of the hippocampus revealed subtle, yet significant, hypoxia-induced modifications during maturation (P15–P51). Anisotropy differences between control and CSH mice were greatest at older ages (>P40) in these regions. Neither somatosensory cortex nor caudate putamen revealed significant differences between control and CSH mice at any age. We assessed control and CSH mice using tests of general activity and cognition for beha... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969021 Sat, 07 Nov 2009 01:37:07 +0100 2969021 http://www.medworm.com/index.php?rid=2969020&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2880%3Frss%3D1 Whether normal word reading includes a stage of visual processing selectively dedicated to word or letter recognition is highly debated. Characterizing pure alexia, a seemingly selective disorder of reading, has been central to this debate. Two main theories claim either that 1) Pure alexia is caused by damage to a reading specific brain region in the left fusiform gyrus or 2) Pure alexia results from a general visual impairment that may particularly affect simultaneous processing of multiple items. We tested these competing theories in 4 patients with pure alexia using sensitive psychophysical measures and mathematical modeling. Recognition of single letters and digits in the central visual field was impaired in all patients. Visual apprehension span was also reduced for both letters and ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969020 Sat, 07 Nov 2009 01:37:07 +0100 2969020 http://www.medworm.com/index.php?rid=2969019&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2865%3Frss%3D1 To understand the relationship between the structure and function of primate neocortical areas at a molecular level, we have been screening for genes differentially expressed across macaque neocortical areas by restriction landmark cDNA scanning (RLCS). Here, we report enriched expression of the paraneoplastic antigen-like 5 gene (PNMA5) in association areas but not in primary sensory areas, with the lowest expression level in primary visual cortex. In situ hybridization in the primary sensory areas revealed PNMA5 mRNA expression restricted to layer II. Along the ventral visual pathway, the expression gradually increased in the excitatory neurons from the primary to higher visual areas. This differential expression pattern was very similar to that of retinol-binding protein (RBP) mRNA, ano... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969019 Sat, 07 Nov 2009 01:37:07 +0100 2969019 http://www.medworm.com/index.php?rid=2969018&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2848%3Frss%3D1 The parietal mechanisms for the control of hand movement trajectory were studied by recording cell activity in area 5 of monkeys making direct reaches to visual targets and online corrections of movement trajectory, after change of target location in space. The activity of hand-related cells was fitted with a linear model including hand position, movement direction, and speed. The neural activity modulation mostly led, but also followed, hand movement. When a change of hand trajectory occurred, the pattern of activity associated with the movement to the first target evolved into that typical of the movement to the second one, thus following the corresponding variations of the hand kinematics. The visual signal concerning target location in space did not influence the firing activity associ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969018 Sat, 07 Nov 2009 01:37:07 +0100 2969018 http://www.medworm.com/index.php?rid=2969017&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2838%3Frss%3D1 The impact of developmental ablation of Pax6 function on morphology and functional connectivity of the adult cerebrum was studied in cortex-specific Pax6 knockout mice (Pax6cKO) using structural magnetic resonance imaging (MRI), manganese-enhanced MRI, and diffusion tensor MRI in conjunction with fiber tractography. Mutants presented with decreased volumes of total brain and olfactory bulb, reduced cortical thickness, and altered layering of the piriform cortex. Tracking of major neuronal fiber bundles revealed a disorganization of callosal fibers with an almost complete lack of interhemispheric connectivity. In Pax6cKO mice intrahemispheric callosal fibers as well as intracortical fibers were predominantly directed along a rostrocaudal orientation instead of a left–right and dorsove... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969017 Sat, 07 Nov 2009 01:37:07 +0100 2969017 http://www.medworm.com/index.php?rid=2969016&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2827%3Frss%3D1 Spatial memory formation is enabled through synaptic information processing, in the form of persistent strengthening and weakening of synapses, within the hippocampus. It is, however, unclear how relevant spatial information is selected for encoding, in preference to less pertinent information. As the noradrenergic locus coeruleus (LC) becomes active in response to novel experiences, we hypothesized that the LC may provide the saliency signal required to promote hippocampal encoding of relevant information through changes in synaptic strength. Test pulse stimulation evoked stable basal synaptic transmission at Schaffer collateral (SC)–CA1 stratum radiatum synapses in freely behaving adult rats. Coupling of these test pulses with electrical stimulation of the LC induced long-term depr... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969016 Sat, 07 Nov 2009 01:37:07 +0100 2969016 http://www.medworm.com/index.php?rid=2969015&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2810%3Frss%3D1 Intrinsic properties, morphology, and local network circuitry of identified layer 5 and layer 6 auditory corticothalamic neurons were compared. We injected fluorescent microspheres into the mouse auditory thalamus to prelabel corticothalamic neurons, then recorded and filled labeled layer 5 or layer 6 auditory cortical neurons in vitro. We observed low-threshold bursting in adult, but not juvenile, layer 5 corticothalamic neurons that was voltage and time dependent with nonlinear input–output properties, whereas adult layer 6 corticothalamic neurons demonstrated a regular spiking. Layer 5 corticothalamic neurons had larger somata, thicker apical dendrites and were more likely to have a layer 1 apical dendrite than layer 6 neurons. Using laser photostimulation, identified layer 5 cort... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969015 Sat, 07 Nov 2009 01:37:07 +0100 2969015 http://www.medworm.com/index.php?rid=2969014&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2803%3Frss%3D1 When paired with aversive events, visual conditioned stimuli (CS) provoke increased activations in visual cortex. It is unclear however whether these changes reflect cognitive processes such as expectancy of the aversive unconditioned stimulus (US), or implicit associative learning of the contingencies outside awareness. Here, we used the "gambler's fallacy" phenomenon to parametrically and inversely manipulate the expectancy of an US and the number of conditioning trials: Increasing the number of CS–US pairings was associated with participants expecting the US to be less likely and vice versa. Magnetocortical activity evoked by the CS in occipital and supplementary motor areas was linearly related to the associative strength (number of CS–US pairings), but decreased as a funct... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969014 Sat, 07 Nov 2009 01:37:07 +0100 2969014 http://www.medworm.com/index.php?rid=2969013&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2797%3Frss%3D1 We investigated sex differences in the resting-state neural correlates of Openness to Experience, a universal personality trait defined by cognitive flexibility, attention to feelings, creativity, and preference for novelty. Using resting-state positron-emission tomography from 100 older individuals (>55 years of age), we identified associations between Openness and resting-state regional cerebral blood flow that replicated across 2 assessments of the same sample, approximately 2 years apart. Openness correlated positively with prefrontal activity in women, anterior cingulate activity in men, and orbitofrontal activity in both sexes, which suggests that areas linked to cognitive flexibility (women), monitoring processes (men), and reward and emotional processing (both) underlie individu... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969013 Sat, 07 Nov 2009 01:37:07 +0100 2969013 http://www.medworm.com/index.php?rid=2969012&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2F2767%3Frss%3D1 Semantic memory refers to knowledge about people, objects, actions, relations, self, and culture acquired through experience. The neural systems that store and retrieve this information have been studied for many years, but a consensus regarding their identity has not been reached. Using strict inclusion criteria, we analyzed 120 functional neuroimaging studies focusing on semantic processing. Reliable areas of activation in these studies were identified using the activation likelihood estimate (ALE) technique. These activations formed a distinct, left-lateralized network comprised of 7 regions: posterior inferior parietal lobe, middle temporal gyrus, fusiform and parahippocampal gyri, dorsomedial prefrontal cortex, inferior frontal gyrus, ventromedial prefrontal cortex, and posterior cing... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969012 Sat, 07 Nov 2009 01:37:06 +0100 2969012 http://www.medworm.com/index.php?rid=2969011&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2FNP-c%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969011 Sat, 07 Nov 2009 01:37:06 +0100 2969011 http://www.medworm.com/index.php?rid=2969010&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2FNP-b%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969010 Sat, 07 Nov 2009 01:37:06 +0100 2969010 http://www.medworm.com/index.php?rid=2969009&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2FNP-a%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969009 Sat, 07 Nov 2009 01:37:06 +0100 2969009 http://www.medworm.com/index.php?rid=2969008&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F12%2FNP%3Frss%3D1 (Source: Cerebral Cortex) Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2969008 Sat, 07 Nov 2009 01:37:06 +0100 2969008 http://www.medworm.com/index.php?rid=2870413&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2755%3Frss%3D1 Neurodevelopmental changes regarding interference and magnitude processing were assessed in 3 age groups (children, n = 10; young adults, n = 11; elderly participants, n = 9) by using an functional magnetic resonance imaging version of the numerical Stroop task. Behaviorally, comparable distance and size congruity effects were found in all 3 age groups. Distance effects were most pronounced in the more difficult numerical task, whereas size congruity effects were comparable across tasks. In response to interference, an age-linear trend in the pattern of activation in left and right prefrontal and left middle temporal regions of the brain was observed. This implicates that with increasing age interference control requires increasing effort (possible explanations for children's relatively lo... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870413 Wed, 07 Oct 2009 14:16:19 +0100 2870413 http://www.medworm.com/index.php?rid=2870412&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2746%3Frss%3D1 The human visual pathways that are specialized for object recognition stretch from lateral occipital cortex (LO) to the ventral surface of the temporal lobe, including the fusiform gyrus. Plasticity in these pathways supports the acquisition of visual expertise, but precisely how training affects the different regions remains unclear. We used functional magnetic resonance imaging to measure neural activity in both LO and the fusiform gyrus in radiologists as they detected abnormalities in chest radiographs. Activity in the right fusiform face area (FFA) correlated with visual expertise, measured as behavioral performance during scanning. In contrast, activity in left LO correlated negatively with expertise, and the amount of LO that responded to radiographs was smaller in experts than in n... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870412 Wed, 07 Oct 2009 14:16:19 +0100 2870412 http://www.medworm.com/index.php?rid=2870411&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2736%3Frss%3D1 There are several models of premotor cortex contributions to sensorimotor behavior. For instance, the ventral premotor cortex (PMv) appears to be involved in processing visuospatial object properties for grasping, whereas the dorsal premotor cortex (PMd) is involved in using arbitrary rules to guide advance motor planning. These models have focused on individual movements. Here, we examine the premotor responses evoked during the processing of individual movements functionally embedded in an action. We tested whether processing hand–object interactions and action end states would differentially engage PMv and PMd. We used a repetition suppression (RS)–functional magnetic resonance imaging paradigm in which we independently manipulated the observed grip, the end position of the ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870411 Wed, 07 Oct 2009 14:16:19 +0100 2870411 http://www.medworm.com/index.php?rid=2870410&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2728%3Frss%3D1 Neuroimaging studies examining the effects of aging and neuropsychiatric disorders on the cerebral cortex have largely been based on measures of cortical volume. Given that cortical volume is a product of thickness and surface area, it is plausible that measures of volume capture at least 2 distinct sets of genetic influences. The present study aims to examine the genetic relationships between measures of cortical surface area and thickness. Participants were men in the Vietnam Era Twin Study of Aging (110 monozygotic pairs and 92 dizygotic pairs). Mean age was 55.8 years (range: 51–59). Bivariate twin analyses were utilized in order to estimate the heritability of cortical surface area and thickness, as well as their degree of genetic overlap. Total cortical surface area and average... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870410 Wed, 07 Oct 2009 14:16:19 +0100 2870410 http://www.medworm.com/index.php?rid=2870409&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2719%3Frss%3D1 Adult dendritic arbors and spines can be modulated by environment and gonadal hormones that have been reported to affect also those of hippocampal and prefrontal cortical neurons. Here we investigated whether female gonadal hormones and estrous cycle alter the dendrites of primary cortical neurons. We employed intracellular dye injection in semifixed brain slices and 3-dimensional reconstruction to study the dendritic arbors and spines of the major cortical output cells, layer III and V pyramidal neurons, during different stages of the estrous cycle. Dendritic spines of both pyramidal neurons were more numerous during proestrus than estrus and diestrus, whereas dendritic arbors remained unaffected. Ovariohysterectomy (OHE) reduced dendritic spines by 24–30% in 2 weeks, whereas subcut... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870409 Wed, 07 Oct 2009 14:16:19 +0100 2870409 http://www.medworm.com/index.php?rid=2870408&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2708%3Frss%3D1 Altered levels of tonic/background dopamine in prefrontal cortex (PFC) may underlie modifications of executive cognitive function. We showed previously in rat PFC slices that exogenously supplied background dopamine facilitates induction of long-term potentiation (LTP), a possible cellular substrate for the long-term component of executive cognitive function. In the present study, we characterized cellular and molecular mechanisms underlying this modulatory dopamine effect. We show first that the LTP-facilitating effect of tonic/background dopamine follows an inverted-U shape concentration curve and that the effective level of background dopamine slowly activates postsynaptic extracellular signal-regulated kinases (ERKs) to facilitate LTP. Furthermore, we show the evidence that LTP-inducin... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870408 Wed, 07 Oct 2009 14:16:19 +0100 2870408 http://www.medworm.com/index.php?rid=2870407&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2699%3Frss%3D1 Although it is largely agreed that phonological processing deficits are a major cause of poor reading, the neural origins of phonological processing are not well understood. We now show, for the first time, that phonological decoding, measured with a test of single-nonword reading, is significantly correlated with the timing of subcortical auditory processing and also, to a lesser extent, with the robustness of subcortical representation of the harmonic content of speech, but not with pitch encoding. The relationships we observe between reading and subcortical processing fall along a continuum, with poor readers at one end and good readers at the other. These data suggest that reading skill may depend on the integrity of subcortical auditory mechanisms and are consistent with the idea that... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870407 Wed, 07 Oct 2009 14:16:19 +0100 2870407 http://www.medworm.com/index.php?rid=2870406&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2690%3Frss%3D1 This study investigated whether differential performance on semantic (category) and phonemic (letter) fluency in neurologically normal participants was reflected in regional gray matter density. The participants were 59 highly proficient speakers of 2 languages. Our findings corroborate the importance of the left inferior temporal cortex in semantic relative to phonemic fluency and show this effect to be the same in a first language (L1) and second language (L2). Additionally, we show that the pre-supplementary motor area (pre-SMA) and head of caudate bilaterally are associated with phonemic more than semantic fluency, and this effect is stronger for L2 than L1 in the caudate nuclei. To further validate these structural results, we reanalyzed previously reported functional data and found t... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870406 Wed, 07 Oct 2009 14:16:19 +0100 2870406 http://www.medworm.com/index.php?rid=2870405&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2680%3Frss%3D1 The prefrontal cortex (PFC) has a central role in working memory (WM). Resistance to distraction is considered a fundamental feature of WM and PFC neuronal activity. However, although unexpected stimuli often disrupt our work, little is known about the underlying neuronal mechanisms involved. In the present study, we investigated whether irregularly presented distracters disrupt WM task performance and underlying neuronal activity. We recorded single neuron activity in the PFC of 2 monkeys performing WM tasks and investigated effects of auditory and visual distracters on WM performance and neuronal activity. Distracters impaired memory task performance and affected PFC neuronal activity. Distraction that was of the same sensory modality as the memorandum was more likely to impair WM perfor... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870405 Wed, 07 Oct 2009 14:16:19 +0100 2870405 http://www.medworm.com/index.php?rid=2870404&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2671%3Frss%3D1 Human behavioral data indicate that older adults are slower to perform lexical decisions (LDs) than young adults but show similar reaction time gains when these decisions are primed semantically. The present study explored the functional neuroanatomic bases of these frequently observed behavioral findings. Young and older groups completed unprimed and primed LD tasks while functional magnetic resonance imaging (fMRI) was recorded, using a fully randomized trial design paralleling those used in behavioral research. Results from the unprimed task found that age-related slowing of LD was associated with decreased activation in perceptual extrastriate regions and increased activation in regions associated with higher level linguistic processes, including prefrontal cortex. In contrast to these... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870404 Wed, 07 Oct 2009 14:16:18 +0100 2870404 http://www.medworm.com/index.php?rid=2870403&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2659%3Frss%3D1 This paper shows that the nature of letters—consonant versus vowel—modulates the process of letter position assignment during visual word recognition. We recorded Event Related Potentials while participants read words in a masked priming semantic categorization task. Half of the words included a vowel as initial, third, and fifth letters (e.g., acero [steel]). The other half included a consonant as initial, third, and fifth (e.g., farol [lantern]). Targets could be preceded 1) by the initial, third, and fifth letters (relative position; e.g., aeo—acero and frl—farol), 2) by 3 consonants or vowels that did not appear in the target word (control; e.g., iui—acero and tsb—farol), or 3) by the same words (identity: acero–acero, farol–farol). The r... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870403 Wed, 07 Oct 2009 14:16:18 +0100 2870403 http://www.medworm.com/index.php?rid=2870402&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2651%3Frss%3D1 There is emerging evidence that alterations in dopaminergic transmission can influence semantic processing, yet the neural mechanisms involved are unknown. The influence of levodopa (L-DOPA) on semantic priming was investigated in healthy individuals (n = 20) using event-related functional magnetic resonance imaging with a randomized, double-blind crossover design. Critical prime–target pairs consisted of a lexical ambiguity prime and 1) a target related to the dominant meaning of the prime (e.g., bank–money), 2) a target related to the subordinate meaning (e.g., fence–sword), or 3) an unrelated target (e.g., ball–desk). Behavioral data showed that both dominant and subordinate meanings were primed on placebo. In contrast, there was preserved priming of dominant mea... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870402 Wed, 07 Oct 2009 14:16:18 +0100 2870402 http://www.medworm.com/index.php?rid=2870401&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2640%3Frss%3D1 Gripping objects during everyday manual tasks requires the coordination of muscle contractions and muscle relaxations. The vast majority of studies have focused on muscle contractions. Although previous work has examined the motor cortex during muscle relaxation, the role of brain areas beyond motor cortex remains to be elucidated. The present study used functional magnetic resonance imaging to directly compare slow and precisely controlled force generation and force relaxation in humans. Contralateral primary motor cortex and bilateral caudate nucleus had greater activity during force generation compared with force relaxation. Conversely, right dorsolateral prefrontal cortex (DLPFC) had greater activity while relaxing force compared with generating force. Also, anterior cingulate cortex h... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870401 Wed, 07 Oct 2009 14:16:18 +0100 2870401 http://www.medworm.com/index.php?rid=2870400&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2625%3Frss%3D1 Music performance is an extremely rapid process with low incidence of errors even at the fast rates of production required. This is possible only due to the fast functioning of the self-monitoring system. Surprisingly, no specific data about error monitoring have been published in the music domain. Consequently, the present study investigated the electrophysiological correlates of executive control mechanisms, in particular error detection, during piano performance. Our target was to extend the previous research efforts on understanding of the human action-monitoring system by selecting a highly skilled multimodal task. Pianists had to retrieve memorized music pieces at a fast tempo in the presence or absence of auditory feedback. Our main interest was to study the interplay between audito... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870400 Wed, 07 Oct 2009 14:16:18 +0100 2870400 http://www.medworm.com/index.php?rid=2870399&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2616%3Frss%3D1 It is well established that patients with hemispatial neglect present with severe visuospatial impairments, but studies that have directly investigated visuomotor control have revealed diverging results, with some studies showing that neglect patients perform relatively better on such tasks. The present study compared the visuomotor performance of patients with and without neglect after right-hemisphere stroke with those of age-matched controls. Participants were asked to point either directly towards targets or halfway between two stimuli, both with and without visual feedback during movement. Although we did not find any neglect-specific impairment, both patient groups showed increased reaction times to leftward stimuli as well as decreased accuracies for open loop leftward reaches. We a... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870399 Wed, 07 Oct 2009 14:16:18 +0100 2870399 http://www.medworm.com/index.php?rid=2870398&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2605%3Frss%3D1 We examined the stimulus–response profile during single-pulse transcranial magnetic stimulation (TMS) by measuring motor-evoked potentials (MEPs) with electromyographic monitoring and hemodynamic responses with functional magnetic resonance imaging (fMRI) at 3 Tesla. In 16 healthy subjects, single TMS pulses were irregularly delivered to the left primary motor cortex at a mean frequency of 0.15 Hz with a wide range of stimulus intensities. The measurement of MEP proved a typical relationship between stimulus intensity and MEP amplitude in the concurrent TMS-fMRI environment. In the population-level analysis of the suprathreshold stimulation conditions, significant increases in hemodynamic responses were detected in the motor/somatosensory network, reflecting both direct and remote ef... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870398 Wed, 07 Oct 2009 14:16:18 +0100 2870398 http://www.medworm.com/index.php?rid=2870397&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2595%3Frss%3D1 Dynamic changes in brain structure, activation, and cognitive abilities co-occur during development, but little is known about how changes in brain structure relate to changes in cognitive function or brain activity. By using cortical pattern matching techniques to correlate cortical gray matter thickness and functional brain activity over the entire brain surface in 24 typically developing children, we integrated structural and functional magnetic resonance imaging data with cognitive test scores to identify correlates of mature performance during orthographic processing. Fast-naming individuals activated the right fronto-parietal attention network in response to novel fonts more than slow-naming individuals, and increased activation of this network was correlated with more mature brain m... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870397 Wed, 07 Oct 2009 14:16:18 +0100 2870397 http://www.medworm.com/index.php?rid=2870396&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2579%3Frss%3D1 The medial prefrontal cortex (MPFC) is regarded as a region of the brain that supports self-referential processes, including the integration of sensory information with self-knowledge and the retrieval of autobiographical information. I used functional magnetic resonance imaging and a novel procedure for eliciting autobiographical memories with excerpts of popular music dating to one's extended childhood to test the hypothesis that music and autobiographical memories are integrated in the MPFC. Dorsal regions of the MPFC (Brodmann area 8/9) were shown to respond parametrically to the degree of autobiographical salience experienced over the course of individual 30 s excerpts. Moreover, the dorsal MPFC also responded on a second, faster timescale corresponding to the signature movements of t... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870396 Wed, 07 Oct 2009 14:16:18 +0100 2870396 http://www.medworm.com/index.php?rid=2870395&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2572%3Frss%3D1 Morphological changes in dendritic spines may contribute to the fine tuning of neural network connectivity. The relationship between spine morphology and experience-dependent neuronal activity, however, is largely unknown. In the present study, we combined 2 histological analyses to examine this relationship: 1) Measurement of spines of neurons whose morphology was visualized in brain sections of mice expressing membrane-targeted green florescent protein (Thy1-mGFP mice) and 2) Categorization of CA1 neurons by immunohistochemical monitoring of Arc expression as a putative marker of recent neuronal activity. After mice were exposed to a novel, enriched environment for 60 min, neurons that expressed Arc had fewer small spines and more large spines than Arc-negative cells. These differences w... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870395 Wed, 07 Oct 2009 14:16:18 +0100 2870395 http://www.medworm.com/index.php?rid=2870394&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2561%3Frss%3D1 Most functional magnetic resonance imaging (fMRI) studies examining working memory (WM) load have focused on the prefrontal cortex (PFC) and have demonstrated increased prefrontal activity with increased load. Here we examined WM load effects in the medial temporal lobe (MTL) using an fMRI Sternberg task with novel complex visual scenes. Trials consisted of 3 sequential events: 1) sample presentation (encoding), 2) delay period (maintenance), and 3) probe period (retrieval). During sample encoding, subjects saw either 2 or 4 pictures consecutively. During retrieval, subjects indicated whether the probe picture matched one of the sample pictures. Results revealed that activity in the left anterior hippocampal formation, bilateral retrosplenial area, and left amygdala was greater at retrieva... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870394 Wed, 07 Oct 2009 14:16:18 +0100 2870394 http://www.medworm.com/index.php?rid=2870393&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2548%3Frss%3D1 Meaning retrieval of a word can proceed fast and effortlessly or can be characterized by a controlled search for candidate lexical items and a subsequent selection process. In the current study, we facilitated meaning retrieval by increasing the number of words that were related to the final target word in a triplet (e.g., lion–stripes–tiger). To induce higher search and selection demands, we presented ambiguous words as targets (i.e., homonyms like ball) in half of the trials. Hereby, the dominant (game), low-frequent (dance), or both meanings of the homonym were primed. Participants performed a relatedness judgment during functional magnetic resonance imaging. Activation in a bilateral network (angular gyrus, rostromedial prefrontal cortex) increased linearly with multiple re... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870393 Wed, 07 Oct 2009 14:16:18 +0100 2870393 http://www.medworm.com/index.php?rid=2870392&cid=s_32202_25_f&fid=32202&url=http%3A%2F%2Fcercor.oxfordjournals.org%2Fcgi%2Fcontent%2Fshort%2F19%2F11%2F2535%3Frss%3D1 The cAMP-responsive element-binding protein (CREB) pathway has been involved in 2 major cascades of gene expression regulating neuronal function. The first one presents CREB as a critical component of the molecular switch that controls long-lasting forms of neuronal plasticity and learning. The second one relates CREB to neuronal survival and protection. To investigate the role of CREB-dependent gene expression in neuronal plasticity and survival in vivo, we generated bitransgenic mice expressing A-CREB, an artificial peptide with strong and broad inhibitory effect on the CREB family, in forebrain neurons in a regulatable manner. The expression of A-CREB in hippocampal neurons impaired L-LTP, reduced intrinsic excitability and the susceptibility to induced seizures, and altered both basal ... Cerebral Cortex journals http://www.medworm.com/rss/comments.php?id=2870392 Wed, 07 Oct 2009 14:16:18 +0100 2870392