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 'Brain Topography' source. Tue, 07 Feb 2012 07:05:39 +0100 http://www.medworm.com/index.php?rid=5639580&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22270846%26dopt%3DAbstract In this study, the feasibility of fMRI in the amygdalae at 7 Tesla was investigated. A paradigm based on the presentation of fearful faces was used for stimulation. Previously, opposite effects have been found for presentation of averted and direct gaze fearful faces. Here, we show that (1) sufficiently high temporal SNR values are reached in the amygdalae for detection of small BOLD signal changes and (2) that the BOLD signal in the amygdalae for presentation of a direct or averted gaze in a fearful face depends on stimulus duration. PMID: 22270846 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=5639580 Sun, 22 Jan 2012 05:00:00 +0100 5639580 http://www.medworm.com/index.php?rid=5621572&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22258394%26dopt%3DAbstract In conclusion, we found in this pilot approach no obvious indication for auditory dysfunctions due to direct electromagnetic stimulation of the superior temporal gyrus after one session of rTMS in healthy controls that may be interpreted as unwanted side effects. Nevertheless monitoring of auditory functions is strongly recommended in future clinical trials stimulating the auditory cortex, as this has not been done systematically in the past. PMID: 22258394 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=5621572 Thu, 19 Jan 2012 05:00:00 +0100 5621572 http://www.medworm.com/index.php?rid=5578154&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22218845%26dopt%3DAbstract In this study, we present a set of 800 pairs of semantically related and unrelated visual objects. The images were rated for semantic relatedness by a sample of 132 participants. Furthermore, we analyzed low-level image properties and matched the two semantic categories according to these features. An ERP study confirmed the suitability of this image set for evoking a robust N400 effect of semantic integration. Additionally, using a general linear modeling approach of single-trial data, we also demonstrate that low-level visual image properties and semantic relatedness are in fact only minimally overlapping. The image set is available for download from the authors' website. We expect that the image set will facilitate studies investigating mechanisms of semantic and contextual processing o... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5578154 Thu, 05 Jan 2012 05:00:00 +0100 5578154 http://www.medworm.com/index.php?rid=5578155&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22209936%26dopt%3DAbstract Authors: Zhang M, Zhang G, Yang J, Chen AC PMID: 22209936 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=5578155 Sat, 31 Dec 2011 05:00:00 +0100 5578155 http://www.medworm.com/index.php?rid=5578156&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22207194%26dopt%3DAbstract Authors: Kokkinos V, Zountsas B, Kontogiannis K, Garganis K Abstract Hypothalamic hamartomas (HH) are typically associated with gelastic seizures but also implicated in the genesis of other seizure types. In order to identify networks involved in seizure generation, we performed EEG-fMRI in two adult patients with HH, the first with predominantly gelastic seizures and the second with complex partial and no typical gelastic seizures. The ictal and interictal analysis of the patient with gelastic seizures revealed the involvement of the HH, the cingulate gyrus, the precuneus and the prefrontal cortex. The interictal analysis of the patient with complex partial seizures, showed changes in blood oxygen-level dependent signal over the temporal lobes, the base of the frontal lobe, the ci... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5578156 Fri, 30 Dec 2011 05:00:00 +0100 5578156 http://www.medworm.com/index.php?rid=5549887&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22193361%26dopt%3DAbstract Authors: Sato D, Onishi H, Yamashiro K, Iwabe T, Shimoyama Y, Maruyama A Abstract Water immersion is widely used in physiotherapy and may even improve the functional outcomes of hemiplegic patients after stroke. To investigate the cortical responses to water immersion, functional near-infrared spectroscopy (fNIRS) was used to measure cortical activations in the primary somatosensory area (S1), parietal association area (PAA), supplementary motor area (SMA), and primary motor area (M1). Nine healthy adult males were rested in a sitting position for 15 min with simultaneous measurements of fNIRS, blood pressure, and skin temperature. The fNIRS signal and other physiological parameters were measured under three conditions, the non-immersed condition (baseline control), as the immersi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5549887 Fri, 23 Dec 2011 05:00:00 +0100 5549887 http://www.medworm.com/index.php?rid=5493244&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22130788%26dopt%3DAbstract Authors: Daliri MR Abstract The functional magnetic resonance imaging (fMRI) provides very useful information about the activities from different brain areas during a task. This information can be used to train a classifier and predict the sensory and motor functions and also different mental states of the subject's brain in a particular task. Using a high resolution fMRI, normally the activities from many voxels are obtained with respect to time and not all of these voxels involve actively in a particular task. Here we propose a combination of feature selection strategies using an evolutionary computation algorithm and the support vector machines to find out those feature dimensions that are actively involved in representing the brain activities in a particular task. We show that ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5493244 Thu, 01 Dec 2011 05:00:00 +0100 5493244 http://www.medworm.com/index.php?rid=5456224&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22124535%26dopt%3DAbstract In conclusion, our findings offer one of the first neurobiological descriptions of differences in IRF intensity and percentage of active voxels in visual and somatosensory cortex during a language experiment for a participant with MISViS in the absence of migraine compared to controls. PMID: 22124535 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=5456224 Tue, 29 Nov 2011 05:00:00 +0100 5456224 http://www.medworm.com/index.php?rid=5456226&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22101380%26dopt%3DAbstract Authors: Minati L, Grisoli M, Franceschetti S, Epifani F, Granvillano A, Medford N, Harrison NA, Piacentini S, Critchley HD Abstract Adaptive behaviour requires an ability to obtain rewards by choosing between different risky options. Financial gambles can be used to study effective decision-making experimentally, and to distinguish processes involved in choice option evaluation from outcome feedback and other contextual factors. Here, we used a paradigm where participants evaluated 'mixed' gambles, each presenting a potential gain and a potential loss and an associated variable outcome probability. We recorded neural responses using autonomic monitoring, electroencephalography (EEG) and functional neuroimaging (fMRI), and used a univariate, parametric design to test for correlatio... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5456226 Sun, 20 Nov 2011 05:00:00 +0100 5456226 http://www.medworm.com/index.php?rid=5456225&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22102157%26dopt%3DAbstract We report an approach to perform source connectivity analysis from MEG, and initially evaluate this approach to interictal MEG to localize epileptogenic foci and analyze interictal discharge propagations in patients with medically intractable epilepsy. Cortical activities were reconstructed from MEG using individual realistic geometry boundary element method head models. Directional connectivity among cortical regions of interest was then estimated using directed transfer function. The MEG source connectivity analysis method was implemented in the eConnectome software, which is open-source and freely available at http://econnectome.umn.edu . As an initial evaluation, the method was applied to study MEG interictal spikes from five epilepsy patients. Estima... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5456225 Sat, 19 Nov 2011 05:00:00 +0100 5456225 http://www.medworm.com/index.php?rid=5420119&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22080232%26dopt%3DAbstract Authors: Kalda T, Minati L Abstract The purpose of this study was to determine whether infrequent scale violations in a sequence of in-key notes are detected when the deviants are matched for frequency of occurrence and preceding intervals with the control notes. We further investigated whether the detectability of scale violations is modulated by the presence of melodic context and by the level of musical training. Event related potentials were recorded from 14 musicians and 13 non-musicians. In non-musicians, the out-of-key notes elicited an early right anterior negativity (ERAN), which appeared prominently over right frontal sites only when presented within structured sequences; no effects were found when the out-of-key notes were presented within scrambled sequences. In musicia... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5420119 Sun, 13 Nov 2011 05:00:00 +0100 5420119 http://www.medworm.com/index.php?rid=5420121&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22080221%26dopt%3DAbstract Authors: Latinus M, Taylor MJ Abstract Gender is salient, socially critical information obtained from faces and voices, yet the brain processes underlying gender discrimination have not been well studied. We investigated neural correlates of gender processing of voices in two ERP studies. In the first, ERP differences were seen between female and male voices starting at 87 ms, in both spatial-temporal and peak analyses, particularly the fronto-central N1 and P2. As pitch differences may drive gender differences, the second study used normal, high- and low-pitch voices. The results of these studies suggested that differences in pitch produced early effects (27-63 ms). Gender effects were seen on N1 (120 ms) with implicit pitch processing (study 1), but were not seen with manipula... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5420121 Sat, 12 Nov 2011 05:00:00 +0100 5420121 http://www.medworm.com/index.php?rid=5420120&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22080222%26dopt%3DAbstract Authors: Chen AC, Theuvenet PJ, de Munck JC, Peters MJ, van Ree JM, Lopes da Silva FL Abstract Motor dominance is well established, but sensory dominance is much less clear. We therefore studied the cortical evoked magnetic fields using magnetoencephalography (MEG) in a group of 20 healthy right handed subjects in order to examine whether standard electrical stimulation of the median and ulnar nerve demonstrated sensory lateralization. The global field power (GFP) curves, as an indication of cortical activation, did not depict sensory lateralization to the dominant left hemisphere. Comparison of the M20, M30, and M70 peak latencies and GFP values exhibited no statistical differences between the hemispheres, indicating no sensory hemispherical dominance at these latencies for each n... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5420120 Sat, 12 Nov 2011 05:00:00 +0100 5420120 http://www.medworm.com/index.php?rid=5344985&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22015572%26dopt%3DAbstract In this study sixteen healthy participants listened to spoken sentences. We performed whole-brain fMRI group statistics and region of interest analysis with anatomically defined regions of interest (auditory core and association areas). We discovered that the protocol, which included a short cluster-onset asynchrony (7.5 s), yielded more advantageous results than the other protocols, which involved longer cluster-onset asynchrony. The short cluster-onset asynchrony protocol exhibited a larger number of activated voxels and larger mean effect sizes with lower standard errors. Our findings suggest that, contrary to prior experience, a short cluster-onset asynchrony is advantageous because more stimuli can be delivered within any given period of time. Alternatively, a given number of stimuli... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5344985 Fri, 21 Oct 2011 04:00:00 +0100 5344985 http://www.medworm.com/index.php?rid=5327821&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22002490%26dopt%3DAbstract Authors: Jakab A, Molnár PP, Bogner P, Béres M, Berényi EL Abstract The aim of this work was to use probabilistic diffusion tractography to examine the organization of the human insular cortex based on the similarities of its remote projections. Forty right-handed healthy subjects (33.8 ± 12.7 years old) with no history of neurological injury were included in the study. After the spatial standardization of diffusion tensor images, insular cortical masks were delineated based on the Harvard-Oxford Cortical Atlas and were used to initiate fibertracking. Cluster analysis by the k-means algorithm was employed to partition the insular voxels into two groups that featured the most distinct distribution of connections. In order to perform volumetric comparisons, the assigned label ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5327821 Sat, 15 Oct 2011 04:00:00 +0100 5327821 http://www.medworm.com/index.php?rid=5327822&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21993841%26dopt%3DAbstract Authors: Zhang M, Zhang G, Ynag J, Chen AC Abstract The aim of this study was to investigate the effect of 400 ml whole blood donation on the human electroencephalogram (EEG) and hematology, not earlier reported in the literature. EEG activity was recorded from ten male blood donors (experiment group) before, during and after blood donation (i.e., 400 ml whole blood withdrawal). EEG topography and regional spectral field powers analyses were carried out via fast Fourier transformation. The venous hemoglobin (Hb) concentration was measured with a hematology analyzer. In the control investigation, 12 male age-matched volunteers (control group) were kept in semi-sitting position for the duration of a blood donation without actually vena puncture. The volunteers had no prior experien... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5327822 Thu, 13 Oct 2011 04:00:00 +0100 5327822 http://www.medworm.com/index.php?rid=5246942&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21928100%26dopt%3DAbstract Authors: Stark A, Meiner Z, Lefkovitz R, Levin N Abstract Motor dysfunction and recovery following stroke and rehabilitation are associated with primary motor cortex plasticity. To better track these effects we studied two patients with sub-acute sub-cortical stroke causing hemiparesis, who underwent an effective behavioral treatment termed Constraint Induced Movement Therapy (CIMT). The therapy involves 2 weeks of intensive motor training of the hemiparetic limb coupled with immobilization of the unaffected limb. The study included a longitudinal series of clinical evaluations and fMRI scans, before and after the treatment. The fMRI task included wrist, elbow, or ankle movements. Activity in the M1 upper-limb region of control subjects was stable, strictly contralateral, and simi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5246942 Sun, 18 Sep 2011 04:00:00 +0100 5246942 http://www.medworm.com/index.php?rid=5218976&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21912974%26dopt%3DAbstract Authors: Malmivuo J Abstract Since the detection of the first biomagnetic signals in 1963 there has been continuous discussion on the properties and relative merits of bioelectric and biomagnetic measurements. In this review article it is briefly discussed the early history of this controversy. Then the theory of the independence and interdependence of bioelectric and biomagnetic signals is explained, and a clinical study on ECG and MCG that strongly supports this theory is presented. The spatial resolutions of EEG and MEG are compared in detail, and the issue of the maximum number of electrodes in EEG is also discussed. Finally, some special properties of EEG and MEG methods are described. In brief, the conclusion is that EEG and MEG are only partially independent and their spatia... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5218976 Tue, 13 Sep 2011 04:00:00 +0100 5218976 http://www.medworm.com/index.php?rid=5157320&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21863371%26dopt%3DAbstract In this study, we attempted to specify the time course of common processes between the two modalities with event-related brain potentials (ERPs). High density EEG was recorded on twenty two healthy participants during a handwritten and an oral picture naming task on the same 120 stimuli. Waveform analyses and topographical pattern analyses were combined on stimulus- and response-aligned ERPs in order to cover the whole word encoding processing. Similar electrophysiological correlates between writing and speaking appeared until about 260 ms. According to previous estimations of the time course of spoken production, the time period of identical electrophysiological activity corresponds to visual (0-150 ms) semantic (150-190 ms) and lexical-semantic (190-275 ms) processes. Then, spoken an... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5157320 Tue, 23 Aug 2011 23:00:00 +0100 5157320 http://www.medworm.com/index.php?rid=5157321&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21858700%26dopt%3DAbstract Authors: Darque A, Del Zotto M, Khateb A, Pegna AJ Abstract The attentional blink (AB) is a transient attentional deficit that occurs when two stimuli that must both be detected are presented within an interval of less than 500 ms. Event-related potential (ERP) investigations have suggested that the AB affects a specific component, the P3, which is suppressed when targets are blinked. In view of the link between the P3 and working memory, it has been suggested that the AB might be due to the inability of the blinked target to access working memory. Interestingly, it seems that faces, due to their saliency, might escape the AB effect when cross-category detection is required (i.e., when the targets are composed of faces versus other categories of stimuli). In the present study we i... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5157321 Sat, 20 Aug 2011 23:00:00 +0100 5157321 http://www.medworm.com/index.php?rid=5157322&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21858551%26dopt%3DAbstract Authors: Pascual-Leone A, Taylor MJ PMID: 21858551 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=5157322 Fri, 19 Aug 2011 23:00:00 +0100 5157322 http://www.medworm.com/index.php?rid=5157323&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21853422%26dopt%3DAbstract Authors: Bartrés-Faz D, Arenaza-Urquijo EM Abstract In the field of ageing and dementia, brain- or cognitive reserve refers to the capacity of the brain to manage pathology or age-related changes thereby minimizing clinical manifestations. The brain reserve capacity (BRC) hypothesis argues that this capacity derives from an individual's unique neural profile (e.g., cell count, synaptic connections, brain volume, etc.). Complimentarily, the cognitive reserve (CR) hypothesis emphasizes inter-individual differences in the effective recruitment of neural networks and cognitive processes to compensate for age-related effects or pathology. Despite an abundance of research, there is scarce literature attempting to synthesize the BRC the CR models. In this paper, we will review important ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5157323 Thu, 18 Aug 2011 23:00:00 +0100 5157323 http://www.medworm.com/index.php?rid=5141353&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21842406%26dopt%3DAbstract Authors: McGinnis SM, Brickhouse M, Pascual B, Dickerson BC Abstract Structural neuroimaging studies have demonstrated that all regions of the cortex are not affected equally by aging, with frontal regions appearing especially susceptible to atrophy. The "last in, first out" hypothesis posits that aging is, in a sense, the inverse of development: late-maturing regions of the brain are preferentially vulnerable to age-related loss of structural integrity. We tested this hypothesis by analyzing age-related changes in regional cortical thickness via three methods: (1) an exploratory linear regression of cortical thickness and age across the entire cortical mantle (2) an analysis of age-related differences in the thickness of zones of cortex defined by functional/cytoarchitectural affi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5141353 Sat, 13 Aug 2011 23:00:00 +0100 5141353 http://www.medworm.com/index.php?rid=5141352&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21842407%26dopt%3DAbstract Authors: Pascual-Leone A, Freitas C, Oberman L, Horvath JC, Halko M, Eldaief M, Bashir S, Vernet M, Shafi M, Westover B, Vahabzadeh-Hagh AM, Rotenberg A Abstract Brain plasticity can be conceptualized as nature's invention to overcome limitations of the genome and adapt to a rapidly changing environment. As such, plasticity is an intrinsic property of the brain across the lifespan. However, mechanisms of plasticity may vary with age. The combination of transcranial magnetic stimulation (TMS) with electroencephalography (EEG) or functional magnetic resonance imaging (fMRI) enables clinicians and researchers to directly study local and network cortical plasticity, in humans in vivo, and characterize their changes across the age-span. Parallel, translational studies in animals can pro... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5141352 Sat, 13 Aug 2011 23:00:00 +0100 5141352 http://www.medworm.com/index.php?rid=5054600&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21769697%26dopt%3DAbstract Authors: Taylor MJ, Mills T, Pang EW Face recognition skills improve steadily across childhood, yet few studies have investigated the development of the neural sources underlying these processes. We investigated the developmental changes in brain activity related specifically to face recognition, using magnetoencephalography (MEG). We studied 70 children (6-19 years) and 20 young adults. Photographs of 240 neutral faces were used in two blocks of 1-back recognition tasks; one block contained faces upright and in the other block, faces were presented inverted. MEG activity was recorded on a 151 sensor CTF/MISL system. A structural MRI was acquired for all subjects. We focussed on the repetition effects of the faces, in a 280-680 ms window, contrasting the repeated faces with the first... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5054600 Mon, 18 Jul 2011 23:00:00 +0100 5054600 http://www.medworm.com/index.php?rid=5054601&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21761265%26dopt%3DAbstract Authors: Pannekamp A, van der Meer E, Toepel U The development of language proficiency extends late into childhood and includes not only producing or comprehending sounds, words and sentences, but likewise larger utterances spanning beyond sentence borders like dialogs. Dialogs consist of information units whose value constantly varies within a verbal exchange. While information is focused when introduced for the first time or corrected in order to alter the knowledge state of communication partners, the same information turns into shared knowledge during the further course of a verbal exchange. In many languages, prosodic means are used by speakers to highlight the informational value of information foci. Our study investigated the developmental pattern of event-related potentials (ER... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5054601 Thu, 14 Jul 2011 23:00:00 +0100 5054601 http://www.medworm.com/index.php?rid=5054602&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21744296%26dopt%3DAbstract In this study, the influence of spatial filtering during the process of sensor selection is addressed. Two of them maximize the Signal to Signal-plus-Noise Ratio (SSNR) for the different sensor subsets while the third one maximizes the differences between the averaged P300 waveform and the non P300 waveform. We show that the locations of the most relevant sensors subsets for the detection of the P300 are highly dependent on the use of spatial filtering. Applied on data from 20 healthy subjects, this study proves that subsets obtained where sensors are suppressed in relation to their individual SSNR are less efficient than when sensors are suppressed in relation to their contribution once the different selected sensors are combined for enhancing the signal. In other words, it highlights the... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5054602 Sat, 09 Jul 2011 23:00:00 +0100 5054602 http://www.medworm.com/index.php?rid=5008744&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21710223%26dopt%3DAbstract Authors: Vanneste S, De Ridder D Tinnitus is an auditory phantom percept with a tone, hissing, or buzzing sound in the absence of any objective physical sound source. Persons with tinnitus engage in a number of health behaviors to manage tinnitus. This can go from prescription medication, masking devices, behavioral training techniques to cortical implants. Potentially less adaptive methods of coping with tinnitus, such as the use of alcohol, are poorly studied. The purpose of this study was to further explore the neurobiological mechanism of tinnitus improvement by the use of alcohol. We observed differences in the alpha, beta and gamma frequency band when comparing resting-state EEG before and after alcohol intake. More precisely increased synchronized alpha1 activity was found in th... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5008744 Mon, 27 Jun 2011 23:00:00 +0100 5008744 http://www.medworm.com/index.php?rid=5008745&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21706377%26dopt%3DAbstract Authors: Voges N, Blanchard S, Wendling F, David O, Benali H, Papadopoulo T, Clerc M, Bénar C Despite the interest in simultaneous EEG-fMRI studies of epileptic spikes, the link between epileptic discharges and their corresponding hemodynamic responses is poorly understood. In this context, biophysical models are promising tools for investigating the mechanisms underlying observed signals. Here, we apply a metabolic-hemodynamic model to simulated epileptic discharges, in part generated by a neural mass model. We analyze the effect of features specific to epileptic neuronal activity on the blood oxygen level dependent (BOLD) response, focusing on the issues of linearity in neurovascular coupling and on the origin of negative BOLD signals. We found both sub- and supra-linearity in simul... Brain Topography journals http://www.medworm.com/rss/comments.php?id=5008745 Sat, 25 Jun 2011 23:00:00 +0100 5008745 http://www.medworm.com/index.php?rid=4912312&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21644026%26dopt%3DAbstract Authors: Schlegel F, Lehmann D, Faber PL, Milz P, Gianotti LR We investigated the spontaneous brain electric activity of 13 skeptics and 16 believers in paranormal phenomena; they were university students assessed with a self-report scale about paranormal beliefs. 33-channel EEG recordings during no-task resting were processed as sequences of momentary potential distribution maps. Based on the maps at peak times of Global Field Power, the sequences were parsed into segments of quasi-stable potential distribution, the 'microstates'. The microstates were clustered into four classes of map topographies (A-D). Analysis of the microstate parameters time coverage, occurrence frequency and duration as well as the temporal sequence (syntax) of the microstate classes revealed significant differ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4912312 Sat, 04 Jun 2011 23:00:00 +0100 4912312 http://www.medworm.com/index.php?rid=4912311&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21644027%26dopt%3DAbstract Authors: Ramon C, Holmes MD The stochastic behavior of the phase synchronization index (SI) in different EEG bands was examined for noninvasive localization of the epileptogenic areas from the short duration (30-60 s), seizure-free and spike-free high density (256 channel) scalp EEG data. We also examined the cross-frequency and cross-electrode coupling in different EEG bands. EEG data of four subjects was used. The seizure areas were localized with subdural recordings with an 8×8 grid electrode array. It was found that the stochastic behavior of the SI in low gamma band (30-50 Hz) was higher in epileptogenic areas. The beta (12-30 Hz) band also showed similar tendencies. The stochastic behavior in theta (3-7 Hz) band was depressed in the seizure area while it was widespread in la... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4912311 Sat, 04 Jun 2011 23:00:00 +0100 4912311 http://www.medworm.com/index.php?rid=4912313&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21630112%26dopt%3DAbstract Authors: Thorpe S, D'Zmura M, Srinivasan R We conducted a cued spatial attention experiment to investigate the time-frequency structure of human EEG induced by attentional orientation of an observer in external auditory space. Seven subjects participated in a task in which attention was cued to one of two spatial locations at left and right. Subjects were instructed to report the speech stimulus at the cued location and to ignore a simultaneous speech stream originating from the uncued location. EEG was recorded from the onset of the directional cue through the offset of the inter-stimulus interval (ISI), during which attention was directed toward the cued location. Using a wavelet spectrum, each frequency band was then normalized by the mean level of power observed in the early part o... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4912313 Tue, 31 May 2011 23:00:00 +0100 4912313 http://www.medworm.com/index.php?rid=4808129&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21499934%26dopt%3DAbstract Authors: Yu QH, Yang J, He KY, Xue LB, Chen AC Sensory gating, a viable function of the brain, is an adaptive mechanism to prevent overstimulation of nervous system. The aim of this study was to examine the effect of homobaric pure (i.e. 100%) oxygen on the human brain at different periods of inhalation. EEG was recorded while an auditory paired-click sensory gating test was conducted during 4 study periods: before inhalation of pure oxygen (Before), inhalation of 100% oxygen (air in control group) for 20 min (Oxy20) and 50 min (Oxy50), 30 min after oxygen (air in control group) inhalation (After). Each of the auditory stimuli elicited 4 clear peaks at 20, 39, 55 and 100 ms in ERPs, demonstrating that sensory gating is a multi-stage process. Comparing the S1-S2 differences of field... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4808129 Wed, 11 May 2011 22:15:42 +0100 4808129 http://www.medworm.com/index.php?rid=4808125&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21547481%26dopt%3DAbstract Authors: Lei X, Hu J, Yao D Brain functional networks extracted from fMRI can improve the accuracy of EEG source localization. However, the coupling between EEG and fMRI remains poorly understood, i.e., whether fMRI networks provide information about the magnitude of neural activity, and whether neural sources demonstrate temporal correlations within each network. In this paper, we present an improved version of the NEtwork-based SOurce Imaging method (iNESOI) through Bayesian model comparison. Different models correspond to various matching between EEG and fMRI, and the appropriate one is selected by data with the model evidence. Synthetic and real data tests show that iNESOI has potential to select the appropriate fMRI priors to reach a better source reconstruction than some other ty... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4808125 Thu, 05 May 2011 23:00:00 +0100 4808125 http://www.medworm.com/index.php?rid=4808126&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21528423%26dopt%3DAbstract Authors: Dosenbach NU, Petersen SE, Schlaggar BL PMID: 21528423 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=4808126 Thu, 28 Apr 2011 23:00:00 +0100 4808126 http://www.medworm.com/index.php?rid=4808127&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21519868%26dopt%3DAbstract Authors: Falvo MJ, Sirevaag EJ, Rohrbaugh JW, Earhart GM Augmented cortical activity during repetitive grasping mitigates repetition-related decrease in cortical efficiency in young adults. It is unclear if similar processes occur with healthy aging. We recorded movement-related cortical potentials (MRCP) during 150 repetitive handgrip contractions at 70% of maximal voluntary contraction (MVC) in healthy young (n = 10) and old (n = 10) adults. Repetitions were grouped into two Blocks (Block 1 and 2: repetitions 1-60 and 91-150, respectively) and analyzed separately to assess the effects of aging and block. EMG of the flexor digitorum superficialis and handgrip force were also recorded. No changes in EMG or MVC were observed across blocks for either group. Significant interactions (... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4808127 Mon, 25 Apr 2011 23:00:00 +0100 4808127 http://www.medworm.com/index.php?rid=4808128&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21516489%26dopt%3DAbstract Authors: Brandeis D, Koenig T, Wackermann J PMID: 21516489 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=4808128 Sat, 23 Apr 2011 23:00:00 +0100 4808128 http://www.medworm.com/index.php?rid=4808130&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21499933%26dopt%3DAbstract This study investigated maturational differences of selective auditory attention effects on transient evoked responses and 40-Hz auditory steady-state responses between children and adults. Magnetoencephalography (MEG) was recorded from children and adults performing a task where they attended to 40-Hz amplitude-modulated (AM) tones of 1,200 Hz while ignoring 40-Hz AM tones of 800 Hz. By using standard dipole-modeling procedures, the N1m of the transient evoked fields and the 40-Hz ASSRs were localized to secondary and primary auditory cortices, respectively. Source waveforms for the transient evoked fields and ASSRs were reconstructed at these locations and compared between attended and unattended tones. Source waveforms revealed attention enhances the sustained negativity of the transi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4808130 Sat, 16 Apr 2011 23:00:00 +0100 4808130 http://www.medworm.com/index.php?rid=4703440&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21479928%26dopt%3DAbstract Authors: Gordon KA, Wong DD, Valero J, Jewell SF, Yoo P, Papsin BC In the present paper, we review what is currently known about the effects of deafness on the developing human auditory system and ask: Without use, does the immature auditory system lose the ability to normally function and mature? Any change to the structure or function of the auditory pathways resulting from a lack of activity will have important implications for future use through an auditory prosthesis such as a cochlear implant. Data to date show that deafness in children arrests and disrupts normal auditory development. Multiple changes to the auditory pathways occur during the period of deafness with the extent and type of change being dependent upon the age and stage of auditory development at onset of deafness,... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4703440 Sun, 10 Apr 2011 23:00:00 +0100 4703440 http://www.medworm.com/index.php?rid=4703441&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21452018%26dopt%3DAbstract Authors: Aine CJ, Sanfratello L, Adair JC, Knoefel JE, Caprihan A, Stephen JM Many neuroimaging studies of age-related memory decline interpret resultant differences in brain activation patterns in the elderly as reflecting a type of compensatory response or regression to a simpler state of brain organization. Here we review a series of our own studies which lead us to an alternative interpretation, and highlights a couple of potential confounds in the aging literature that may act to increase the variability of results within age groups and across laboratories. From our perspective, level of cognitive functioning achieved by a group of elderly is largely determined by the health of individuals within this group. Individuals with a history of hypertension, for example, are likely to ha... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4703441 Wed, 30 Mar 2011 23:00:00 +0100 4703441 http://www.medworm.com/index.php?rid=4703443&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21445664%26dopt%3DAbstract Authors: Takakura H, Shojaku H, Takamoto K, Urakawa S, Nishijo H, Watanabe Y Intravenous injection of thiamine propyldisulphide (TPD), which induces sensation of a garlic-like odor, has been used as a representative subjective olfactory test in Japan. However, cortical loci activated by TPD still remain unclear. We recorded cerebral hemodynamic responses (changes in Oxy-Hb concentrations) induced by TPD administration using whole-head multi-channel near infrared spectroscopy (NIRS) system based on 3D-MRIs. TPD as an odorant and saline as a control were injected from the cephalic vein in the left forearm in ten male normosmic (five young and five elderly) subjects and five dysosmic elderly patients. The all normosmic, but not dysosmic, subjects felt the garlic-like odor in the all TPD t... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4703443 Mon, 28 Mar 2011 23:00:00 +0100 4703443 http://www.medworm.com/index.php?rid=4703442&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21445665%26dopt%3DAbstract Authors: Trainor LJ, Lee K, Bosnyak DJ Animal models suggest that the brain is particularly neuroplastic early in development, but previous studies have not systematically controlled the auditory environment in human infants and observed the effects on auditory cortical representations. We exposed 4-month-old infants to melodies in either guitar or marimba timbre (infants were randomly assigned to exposure group) for a total of ~160 min over the course of a week, after which we measured electroencephalogram (EEG) responses to guitar and marimba tones at pitches not previously heard during the exposure phase. A frontally negative response with a topography consistent with generation in auditory areas, peaking around 450 ms, was significantly larger for guitar than marimba tones in th... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4703442 Mon, 28 Mar 2011 23:00:00 +0100 4703442 http://www.medworm.com/index.php?rid=4703444&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21442325%26dopt%3DAbstract Authors: Luyster RJ, Wagner JB, Vogel-Farley V, Tager-Flusberg H, Nelson Iii CA Examining the neural correlates associated with processing social stimuli offers a viable option to the challenge of studying early social processing in infants at risk for autism spectrum disorders (ASDs). The present investigation included 32 12-month olds at high risk for ASD and 24 low-risk control infants, defined on the basis of family history. Infants were presented with familiar and unfamiliar faces, and three components of interest were explored for amplitude and latency differences. The anticipated developmental effects of emerging hemispheric asymmetry for face-sensitive components (the N290 and P400) were observed, as were familiarity effects for a component related to attention (the Nc). Althou... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4703444 Sat, 26 Mar 2011 00:00:00 +0100 4703444 http://www.medworm.com/index.php?rid=4643331&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21380858%26dopt%3DAbstract Authors: Jenkins J, Rhone AE, Idsardi WJ, Simon JZ, Poeppel D Most ecologically natural sensory inputs are not limited to a single modality. While it is possible to use real ecological materials as experimental stimuli to investigate the neural basis of multi-sensory experience, parametric control of such tokens is limited. By using artificial bimodal stimuli composed of approximations to ecological signals, we aim to observe the interactions between putatively relevant stimulus attributes. Here we use MEG as an electrophysiological tool and employ as a measure the steady-state response (SSR), an experimental paradigm typically applied to unimodal signals. In this experiment we quantify the responses to a bimodal audio-visual signal with different degrees of temporal (phase) congruity,... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4643331 Sun, 06 Mar 2011 00:00:00 +0100 4643331 http://www.medworm.com/index.php?rid=4643333&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21365309%26dopt%3DAbstract Authors: Cho JH, Hong SB, Jung YJ, Kang HC, Kim HD, Suh M, Jung KY, Im CH Precise identification of epileptogenic zones in patients with intractable drug-resistant epilepsy is critical for successful epilepsy surgery. Numerous source-imaging algorithms for localizing epileptogenic zones based on scalp electroencephalography (EEG) and magnetoencephalography (MEG) have been developed and validated in simulation and experimental studies. Recently, intracranial EEG (iEEG)-based imaging of epileptogenic sources has attracted interest as a promising tool for presurgical evaluation of epilepsy; however, most iEEG studies have focused on localization of epileptogenic zones in focal epilepsy. In the present study, we investigated whether iEEG source imaging is a useful supplementary tool for id... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4643333 Thu, 03 Mar 2011 00:00:00 +0100 4643333 http://www.medworm.com/index.php?rid=4643332&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21365310%26dopt%3DAbstract In this study, using ERPs and the source localization algorithm, LORETA, we seek to examine the brain mechanisms involved in IOR by localizing the different stages of processing after the appearance of a cue that captures attention exogenously. Unlike previous ERP investigations of IOR, this study analyzes the neural activity (via EEG) produced in response to the cue, prior to the appearance of the target. Neural activations were approximately divided into three stages. In the early stage (110-240 ms), involved activations are in the prefrontal cortex, the bilateral intraparietal cortex, and the contralateral occipito-temporal cortex. In the middle stage (240-350 ms), activations are primarily found in the frontal cortex and the parietal cortex. In the late stage (350-650 ms), the main ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4643332 Wed, 02 Mar 2011 00:00:00 +0100 4643332 http://www.medworm.com/index.php?rid=4643334&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21350872%26dopt%3DAbstract Authors: Arsalidou M, Morris D, Taylor MJ Neuroimaging evidence suggests that dynamic facial expressions elicit greater activity than static face stimuli in brain structures associated with social cognition, interpreted as greater ecological validity. However, a quantitative meta-analysis of brain activity associated with dynamic facial expressions is lacking. The current study investigated, using three fMRI experiments, activity elicited by (a) dynamic and static happy faces, (b) dynamic and static happy and angry faces, and (c) dynamic faces and dynamic flowers. In addition, using activation likelihood estimate (ALE) meta-analysis, we determined areas concordant across published studies that (a) used dynamic faces and (b) specifically compared dynamic and static emotional faces. The ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4643334 Fri, 25 Feb 2011 00:00:00 +0100 4643334 http://www.medworm.com/index.php?rid=4473154&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21298332%26dopt%3DAbstract Authors: Foy CM, Daly EM, Glover A, O'Gorman R, Simmons A, Murphy DG, Lovestone S Proton magnetic resonance spectroscopy ((1)H-MRS) studies have previously reported reduced brain N-acetyl aspartate (NAA) and increased myo-inositol (mI) in people with established Alzheimer's disease (AD). The earliest structure affected by AD is the hippocampus but relatively few studies have examined its neuronal integrity by MRS in AD and fewer still in people with amnestic mild cognitive impairment (MCI). We measured the hippocampal concentration of NAA, mI, choline (Cho) and creatine + phosphocreatine (Cr + PCr) in 39 patients with AD, 21 subjects with MCI and 38 age matched healthy elderly controls. Patients with AD had a significantly lower hippocampal [NAA] than controls, with subjects with M... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4473154 Sat, 05 Feb 2011 00:00:00 +0100 4473154 http://www.medworm.com/index.php?rid=4342589&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21203817%26dopt%3DAbstract We examined changes in resting brain dynamics following single TMS pulses, focusing on measures in the phase domain, to assess their sensitivity to stimulation effects. We observed a significant, approximately global increase in EEG relative phase following prolonged (>20 min) single-pulse TMS. In addition, we estimated higher rates of phase fluctuation from the slope of estimated phase curves, and higher numbers of phase resetting intervals following TMS over motor cortex, particularly in frontal and centro-parietal/parietal channels. Phase changes were only significantly different from their pre-TMS values at the end of the stimulation session, which suggests that prolonged single-pulse TMS may result in cumulative changes in neural activity reflected in the phase of the EEG. This is... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4342589 Tue, 04 Jan 2011 00:00:00 +0100 4342589 http://www.medworm.com/index.php?rid=4342590&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21191807%26dopt%3DAbstract Authors: Qiu MG, Ye Z, Li QY, Liu GJ, Xie B, Wang J To explore the changes of brain structure and function in attention-deficit/hyperactivity disorder (ADHD), fifteen ADHD patients (inattention subtype) and 15 normal control participants were recruited, the brain structure and function of these subjects were investigated by combining structural magnetic resonance imaging (MRI), diffusion tensor imaging and resting-state functional MRI. The results showed that ADHD patients had a significant decrease in the volume of the white matter (P = 0.04), and a trend toward decreased volume of brain structures except for the putamen and globus pallidus. The visualization of statistical difference maps of the cortical thickness showed that ADHD patients had focal thinning in bilateral frontal re... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4342590 Thu, 30 Dec 2010 00:00:00 +0100 4342590 http://www.medworm.com/index.php?rid=4201892&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21107673%26dopt%3DAbstract Authors: Visani E, Minati L, Canafoglia L, Gilioli I, Granvillano A, Varotto G, Aquino D, Fazio P, Bruzzone MG, Franceschetti S, Panzica F Electrophysiological studies indicate that Unverricht-Lundborg's disease (ULD), the most common form of progressive myoclonus epilepsy in Europe, is characterized by the involvement of multiple cortical regions in degenerative changes that lead to enhanced excitation and deficient inhibition. We searched for the haemodynamic correlates of these effects using functional MRI (fMRI) of self-paced index extensions, a well-accepted task highlighting significant differences. EEG and fMRI were simultaneously acquired in 11 ULD patients and 16 controls, performing the index extensions individually (event-related task) as well as repetitively (block task). E... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4201892 Wed, 24 Nov 2010 00:00:00 +0100 4201892 http://www.medworm.com/index.php?rid=4186728&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21076861%26dopt%3DAbstract Authors: Bashir S, Edwards D, Pascual-Leone A Low-frequency repetitive transcranial magnetic stimulation (rTMS) can exert local and inter-hemispheric neuromodulatory effects on cortical excitability. These physiologic effects can translate into changes in motor behavior, and may offer valuable therapeutic interventions in recovery from stroke. Neuronavigated TMS can maximize accurate and consistent targeting of a given cortical region, but is a lot more involved that conventional TMS. We aimed to assess whether neuronavigation enhances the physiologic and behavioral effects of low-frequency rTMS. Ten healthy subjects underwent two experimental sessions during which they received 1600 pulses of either navigated or non-navigated 1 Hz rTMS at 90% of the resting motor threshold (RMT) inte... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4186728 Sat, 13 Nov 2010 00:00:00 +0100 4186728 http://www.medworm.com/index.php?rid=4154668&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21057867%26dopt%3DAbstract This study confirmed that the model structure which accounts for the representation of the CBF-CMRO(2) relationship (oxygen supply by the flow vs. oxygen demand from neurons) plays a key role. More generally, this work provides substantial information about the tuning of parameters in the three considered models and about the subsequent interpretation of BOLD signals based on these models. PMID: 21057867 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=4154668 Sat, 06 Nov 2010 00:00:00 +0100 4154668 http://www.medworm.com/index.php?rid=4139812&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21052814%26dopt%3DAbstract We presented participants with faces in phase 1 and later we presented eyes-only in phase 2. For some of these eyes in phase 2, the whole face had been presented in the previous phase, for others identical eyes had been presented. Event-related potentials (ERPs) revealed an N170 component that was more negative when eyes were preceded by a whole face in the previous phase compared to eyes preceded by identical eyes-only. A more positive-going late positive complex (LPC) was also found, suggesting enhanced retrieval of face memory representations when eyes were preceded by whole faces. Our results show that pre-existing representations of face identity can influence early stages of visual encoding, 170 ms after stimulus onset. These effects may reflect top-down modulation by memory on visu... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4139812 Thu, 04 Nov 2010 00:00:00 +0100 4139812 http://www.medworm.com/index.php?rid=4088673&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20945085%26dopt%3DAbstract Authors: Kottlow M, Praeg E, Luethy C, Jancke L Brain mechanisms associated with artistic talents or skills are still not well understood. This exploratory study investigated differences in brain activity of artists and non-artists while drawing previously presented perspective line-drawings from memory and completing other drawing-related tasks. Electroencephalography (EEG) data were analyzed for power in the frequency domain by means of a Fast Fourier Transform (FFT). Low Resolution Brain Electromagnetic Tomography (LORETA) was applied to localize emerging significances. During drawing and related tasks, decreased power was seen in artists compared to non-artists mainly in upper alpha frequency ranges. Decreased alpha power is often associated with an increase in cognitive functionin... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4088673 Wed, 13 Oct 2010 23:00:00 +0100 4088673 http://www.medworm.com/index.php?rid=4064044&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20938730%26dopt%3DAbstract Authors: Laganaro M, Perret C Most EEG studies analysing speech production with event related brain potential (ERP) have adopted silent metalinguistic tasks or delayed or tacit picture naming in order to avoid possible artefacts during motor preparation. A central issue in the interpretation of these results is whether the processes involved in those tasks are comparable to those involved in overt speech production. In the present study we addressed a methodological issue about the integration of stimulus-aligned and response-aligned ERPs in immediate overt picture naming in comparison to delayed production, coupled with a theoretical point on the effect of word Age of Acquisition (AoA). High density EEG recordings were used and waveform analyses and spatio-temporal segmentation were c... Brain Topography journals http://www.medworm.com/rss/comments.php?id=4064044 Mon, 11 Oct 2010 23:00:00 +0100 4064044 http://www.medworm.com/index.php?rid=3955436&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20820898%26dopt%3DAbstract Authors: Michels L, Bucher K, Brem S, Halder P, Lüchinger R, Liechti M, Martin E, Jeanmonod D, Kröll J, Brandeis D Greater low frequency power (<8 Hz) in the electroencephalogram (EEG) at rest is normal in the immature developing brain of children when compared to adults. Children with epilepsy also have greater low frequency interictal resting EEG activity. Whether these power elevations reflect brain immaturity due to a developmental lag or the underlying epileptic pathophysiology is unclear. The present study addresses this question by analyzing spectral EEG topographies and sources for normally developing children and children with epilepsy. We first compared the resting EEG of healthy children to that of healthy adults to isolate effects related to normal brain immaturity... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3955436 Sat, 04 Sep 2010 23:00:00 +0100 3955436 http://www.medworm.com/index.php?rid=3885623&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20717841%26dopt%3DAbstract Authors: Fogelson N, Fernandez-Del-Olmo M We investigated the effects of stimulus presentation rates on local contextual processing. Local context was defined as the occurrence of a short predictive series of stimuli occurring before delivery of a target event. EEG was recorded in 12 subjects during two sessions: a slower (150 ms stimulus presentation, 1,000 ms interstimulus interval (ISI)) and a faster session (50 ms stimulus presentation, 800 ms ISI). Stimuli were presented to either the left or right visual field and consisted of 15% targets (downward facing triangle) and 85% of equal numbers of three types of standards (triangles facing left, upwards and right). Recording blocks consisted of targets preceded by randomized sequences of standards and by sequences including a predicti... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3885623 Tue, 17 Aug 2010 23:00:00 +0100 3885623 http://www.medworm.com/index.php?rid=3885622&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20717842%26dopt%3DAbstract Authors: Pourtois G Advanced ERP topographic mapping techniques were used to study error monitoring functions in human adult participants, and test whether proactive attentional effects during the pre-response time period could later influence early error detection mechanisms (as measured by the ERN component) or not. Participants performed a speeded go/nogo task, and made a substantial number of false alarms that did not differ from correct hits as a function of behavioral speed or actual motor response. While errors clearly elicited an ERN component generated within the dACC following the onset of these incorrect responses, I also found that correct hits were associated with a different sequence of topographic events during the pre-response baseline time-period, relative to errors. A... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3885622 Tue, 17 Aug 2010 23:00:00 +0100 3885622 http://www.medworm.com/index.php?rid=3833791&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20686832%26dopt%3DAbstract In this study, the propagation of brain activity during a transitive reasoning task was investigated and compared to the propagation during a simple memory task. We studied EEG transmission patterns obtained for physiological indicators of brain activity and determined whether there are frequency bands specifically related to this type of cognitive operations. The analysis was performed by means of the directed transfer function. The transmission patterns were determined in the theta, alpha and gamma bands. The results show stronger transmissions in theta and alpha bands from frontal to parietal as well as within frontal regions in reasoning trials comparing to memory trials. The increase in theta and alpha transmissions was accompanied by flows in gamma band from right posterior to left p... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3833791 Wed, 04 Aug 2010 23:00:00 +0100 3833791 http://www.medworm.com/index.php?rid=3806104&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20665099%26dopt%3DAbstract Authors: Yuval-Greenberg S, Deouell LY We previously showed that the transient broadband induced gamma-band response in EEG (iGBRtb) appearing around 200-300 ms following a visual stimulus reflects the contraction of extra-ocular muscles involved in the execution of saccades, rather than neural oscillations. Several previous studies reported induced gamma-band responses also following auditory stimulation. It is still an open question whether, similarly to visual paradigms, such auditory paradigms are also sensitive to the saccadic confound. In the current study we address this question using simultaneous eye-tracking and EEG recordings during an auditory oddball paradigm. Subjects were instructed to respond to a rare target defined by sound source location, while fixating on a central... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3806104 Tue, 27 Jul 2010 23:00:00 +0100 3806104 http://www.medworm.com/index.php?rid=3806105&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20652828%26dopt%3DAbstract The objective of our study was to determine the presence and extent of functional abnormalities outside of a defined structural abnormality in epilepsy patients with mTLE. We used a prospective age-matched controlled design to study eight consecutive patients with MTS who were undergoing epilepsy surgery evaluation. Magnetoencephalography was used to localize the sources of electromagnetic abnormality. Proton magnetic resonance spectroscopy ((1)H-MRS) measured integrated peak areas for N-acetyl compounds (NAA) and choline-containing compounds (Cho) to determine regions of metabolic abnormality. All eight subjects had predominant electromagnetic abnormality in the temporal lobe ipsilateral to the MTS. All eight subjects had lower NAA/Cho ratios in the region of electromagnetic abnormality w... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3806105 Thu, 22 Jul 2010 23:00:00 +0100 3806105 http://www.medworm.com/index.php?rid=3806106&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20652392%26dopt%3DAbstract Authors: Bai X, Towle VL, van Drongelen W, He B The aim of the present study was to assess the feasibility of identifying the primary hand sensory area and central sulcus in pediatric patients using the cortical potential imaging (CPI) method from the scalp recorded somatosensory evoked potentials (SEPs). The CPI method was used to reconstruct the cortical potential distribution from the scalp potentials with the boundary element (3-layer: scalp, skull and brain) head model based on MR images of individual subjects. The cortical potentials estimated from the pre-operative scalp SEPs of four pediatric patients, were compared with the post-op subdural SEP recordings made in the same subjects. Estimated and directly recorded cortical SEP maps showed comparable spatial patterns on the cort... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3806106 Tue, 20 Jul 2010 23:00:00 +0100 3806106 http://www.medworm.com/index.php?rid=3777599&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20640882%26dopt%3DAbstract Authors: Ahlfors SP, Han J, Belliveau JW, Hämäläinen MS An important difference between magnetoencephalography (MEG) and electroencephalography (EEG) is that MEG is insensitive to radially oriented sources. We quantified computationally the dependency of MEG and EEG on the source orientation using a forward model with realistic tissue boundaries. Similar to the simpler case of a spherical head model, in which MEG cannot see radial sources at all, for most cortical locations there was a source orientation to which MEG was insensitive. The median value for the ratio of the signal magnitude for the source orientation of the lowest and the highest sensitivity was 0.06 for MEG and 0.63 for EEG. The difference in the sensitivity to the source orientation is expected to contribute to... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3777599 Sat, 17 Jul 2010 23:00:00 +0100 3777599 http://www.medworm.com/index.php?rid=3750657&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20623171%26dopt%3DAbstract Authors: Hamidi M, Johson JS, Feredoes E, Postle BR A common procedure for studying the effects on cognition of repetitive transcranial magnetic stimulation (rTMS) is to deliver rTMS concurrent with task performance, and to compare task performance on these trials versus on trials without rTMS. Recent evidence that TMS can have effects on neural activity that persist longer than the experimental session itself, however, raise questions about the assumption of the transient nature of rTMS that underlies many concurrent (or "online") rTMS designs. To our knowledge, there have been no studies in the cognitive domain examining whether the application of brief trains of rTMS during specific epochs of a complex task may have effects that spill over into subsequent task epochs, and perhaps in... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3750657 Fri, 09 Jul 2010 23:00:00 +0100 3750657 http://www.medworm.com/index.php?rid=3742740&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20614232%26dopt%3DAbstract Authors: De Vico Fallani F, Rodrigues FA, da Fontoura Costa L, Astolfi L, Cincotti F, Mattia D, Salinari S, Babiloni F In the present study, we propose a theoretical graph procedure to investigate multiple pathways in brain functional networks. By taking into account all the possible paths consisting of h links between the nodes pairs of the network, we measured the global network redundancy R ( h ) as the number of parallel paths and the global network permeability P ( h ) as the probability to get connected. We used this procedure to investigate the structural and dynamical changes in the cortical networks estimated from a dataset of high-resolution EEG signals in a group of spinal cord injured (SCI) patients during the attempt of foot movement. In the light of a statistical contrast... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3742740 Wed, 07 Jul 2010 23:00:00 +0100 3742740 http://www.medworm.com/index.php?rid=3702102&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20577795%26dopt%3DAbstract In conclusion, the present results have demonstrated that contralateral high-gamma neuromagnetic activities are potential biomarkers for the accurate localization of the primary motor cortex in children. In addition, the interesting finding of the ipsilateral high-gamma neuromagnetic activities opens a new window for us to understand the developmental changes of the hemispherical functional lateralization in the motor system. PMID: 20577795 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=3702102 Thu, 24 Jun 2010 23:00:00 +0100 3702102 http://www.medworm.com/index.php?rid=3702103&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20574764%26dopt%3DAbstract Authors: Larsson PG, Eeg-Olofsson O, Michel CM, Seeck M, Lantz G Different neuroimaging techniques (fMRI, spectroscopy, PET) are being used to evaluate candidate drugs in pharmacological development. In patients with epilepsy fast propagation of the epileptiform activity between different brain areas occurs. Electric Source Imaging (ESI), in contrast to the aforementioned techniques, has a millisecond time resolution, allowing visualization of this fast propagation. The purpose of the current project was to use ESI to investigate whether introduction of an antiepileptic drug (levetiracetam, LEV) would change the propagation patterns of the interictal epileptiform activity. Thirty patients with epilepsy were subject to an EEG recording before (pre-LEV) and after (in-LEV) introduction of... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3702103 Wed, 23 Jun 2010 23:00:00 +0100 3702103 http://www.medworm.com/index.php?rid=3677005&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20549553%26dopt%3DAbstract Authors: Khateb A, Pegna AJ, Landis T, Mouthon MS, Annoni JM The question of the cognitive nature and the cerebral origins of the event-related potential (ERP) N400 component has frequently been debated. Here, the N400 effects were analyzed in three tasks. In the semantic task, subjects decided whether sequentially presented word pairs were semantically related or unrelated. In the phonologic (rhyme detection) task, they decided if words were phonologically related or not. In the image categorization task, they decided whether images were categorically related or not. Difference waves between ERPs to unrelated and related conditions (defined here as the N400 effect) demonstrated a greater amplitude and an earlier peak latency effect in the image than in semantic and phonologic tasks. I... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3677005 Fri, 11 Jun 2010 23:00:00 +0100 3677005 http://www.medworm.com/index.php?rid=3610580&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20502956%26dopt%3DAbstract Authors: Takamoto K, Hori E, Urakawa S, Sakai S, Ishikawa A, Kohno S, Ono T, Nishijo H Acupuncture stimulation at specific points, or trigger points (TPs), elicits sensations called "de-qi". De-qi sensations relate to the clinical efficacy of the treatment. However, it is neither clear whether de-qi sensations are associated with TPs, nor clear whether acupuncture effects on brain activity are associated with TPs or de-qi. We recorded cerebral hemodynamic responses during acupuncture stimulation at TPs and non-TPs by functional near-infrared spectroscopy. The acupuncture needle was inserted into both TPs and non-TPs within the right extensor muscle in the forearm. Typical acupuncture needle manipulation was conducted eight times for 15 s. The subjects pressed a button if they felt a de... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3610580 Tue, 25 May 2010 23:00:00 +0100 3610580 http://www.medworm.com/index.php?rid=3582374&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20480221%26dopt%3DAbstract In this study we illustrate a methodology able to follow and study concurrent and simultaneous brain processes during cooperation between individuals, with non invasive EEG methodologies. We collected data from fourteen pairs of subjects while they were playing a card game with EEG. Data collection was made simultaneously on all the subjects during the card game. An extension of the Granger-causality approach allows us to estimate the functional connection between signals estimated from different Regions of Interest (ROIs) in different brains during the analyzed task. Finally, with the use of graph theory, we contrast the functional connectivity patterns of the two players belonging to the same team. Statistically significant functional connectivities were obtained from signals estimated i... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3582374 Mon, 17 May 2010 23:00:00 +0100 3582374 http://www.medworm.com/index.php?rid=3556897&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20454842%26dopt%3DAbstract Authors: Babiloni F PMID: 20454842 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=3556897 Fri, 07 May 2010 23:00:00 +0100 3556897 http://www.medworm.com/index.php?rid=3531350&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20440549%26dopt%3DAbstract This study determined bidirectional electrical conductivities from pediatric epilepsy surgery patients. Electrical conductivities perpendicular and parallel to the pial surface of neocortex and subcortical white matter (n = 15) were measured using the 4-electrode technique and compared with clinical variables. Mean (+/-SD) electrical conductivities were 0.10 +/- 0.01 S/m, and varied by 243% from patient to patient. Perpendicular and parallel conductivities differed by 45%, and the larger values were perpendicular to the pial surface in 47% and parallel in 40% of patients. A perpendicular principal axis was associated with normal, while isotropy and parallel principal axes were linked with epileptogenic lesions by MRI. Electrical conductivities were decreased in patients with cortical dyspl... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3531350 Mon, 03 May 2010 23:00:00 +0100 3531350 http://www.medworm.com/index.php?rid=3515874&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20422446%26dopt%3DAbstract Authors: De Lucia M, Michel CM, Murray MM Single-trial analysis of human electroencephalography (EEG) has been recently proposed for better understanding the contribution of individual subjects to a group-analyis effect as well as for investigating single-subject mechanisms. Independent Component Analysis (ICA) has been repeatedly applied to concatenated single-trial responses and at a single-subject level in order to extract those components that resemble activities of interest. More recently we have proposed a single-trial method based on topographic maps that determines which voltage configurations are reliably observed at the event-related potential (ERP) level taking advantage of repetitions across trials. Here, we investigated the correspondence between the maps obtained by ICA v... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3515874 Mon, 26 Apr 2010 23:00:00 +0100 3515874 http://www.medworm.com/index.php?rid=3491343&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20405196%26dopt%3DAbstract Authors: Bianchi L, Sami S, Hillebrand A, Fawcett IP, Quitadamo LR, Seri S We investigated which evoked response component occurring in the first 800 ms after stimulus presentation was most suitable to be used in a classical P300-based brain-computer interface speller protocol. Data was acquired from 275 Magnetoencephalographic sensors in two subjects and from 61 Electroencephalographic sensors in four. To better characterize the evoked physiological responses and minimize the effect of response overlap, a 1000 ms Inter Stimulus Interval was preferred to the short (<400 ms) trial length traditionally used in this class of BCIs. To investigate which scalp regions conveyed information suitable for BCI, a stepwise linear discriminant analysis classifier was used. The method iteratively... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3491343 Mon, 19 Apr 2010 23:00:00 +0100 3491343 http://www.medworm.com/index.php?rid=3457203&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20376546%26dopt%3DAbstract We present a simple and effective method to test whether an event consistently activates a set of brain electric sources across repeated measurements of event-related scalp field data. These repeated measurements can be single trials, single subject ERPs, or ERPs from different studies. The method considers all sensors simultaneously, but can be applied separately to each time frame or frequency band of the data. This allows limiting the analysis to time periods and frequency bands where there is positive evidence of a consistent relation between the event and some brain electric sources. The test may therefore avoid false conclusions about the data resulting from an inadequate selection of the analysis window and bandpass filter, and permit the exploration of alternate hypotheses when gro... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3457203 Wed, 07 Apr 2010 23:00:00 +0100 3457203 http://www.medworm.com/index.php?rid=3450160&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20364434%26dopt%3DAbstract Authors: Bojak I, Oostendorp TF, Reid AT, Kötter R Progress in functional neuroimaging of the brain increasingly relies on the integration of data from complementary imaging modalities in order to improve spatiotemporal resolution and interpretability. However, the usefulness of merely statistical combinations is limited, since neural signal sources differ between modalities and are related non-trivially. We demonstrate here that a mean field model of brain activity can simultaneously predict EEG and fMRI BOLD with proper signal generation and expression. Simulations are shown using a realistic head model based on structural MRI, which includes both dense short-range background connectivity and long-range specific connectivity between brain regions. The distribution of modeled neu... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3450160 Sat, 03 Apr 2010 23:00:00 +0100 3450160 http://www.medworm.com/index.php?rid=3409021&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20336360%26dopt%3DAbstract Authors: Slabu LM Although auditory information is processed in several subcortical nuclei, most fMRI studies focus solely on the auditory cortex and do not take brainstem responses into account. One common difficulty in obtaining clear functional brainstem recordings is due to heartbeat related motion, manifested in the rostro-caudal and in the ventro-dorsal directions in the contraction phase of the heart. The aim of this study was to investigate the effect of slice orientation on auditory functional magnetic resonance imagining (fMRI) measurements with respect to the pattern of brainstem oscillation. Fourteen healthy volunteers listened monaurally to modulated pink noise. Blood oxygenation level dependent (BOLD) contrast was performed with an echo-planar image (EPI) sequence using a... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3409021 Thu, 25 Mar 2010 00:00:00 +0100 3409021 http://www.medworm.com/index.php?rid=3409022&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20333460%26dopt%3DAbstract Authors: Blanke O, Ionta S, Fornari E, Mohr C, Maeder P The processing of human bodies is important in social life and for the recognition of another person's actions, moods, and intentions. Recent neuroimaging studies on mental imagery of human body parts suggest that the left hemisphere is dominant in body processing. However, studies on mental imagery of full human bodies reported stronger right hemisphere or bilateral activations. Here, we measured functional magnetic resonance imaging during mental imagery of bilateral partial (upper) and full bodies. Results show that, independently of whether a full or upper body is processed, the right hemisphere (temporo-parietal cortex, anterior parietal cortex, premotor cortex, bilateral superior parietal cortex) is mainly involved in mental... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3409022 Wed, 24 Mar 2010 00:00:00 +0100 3409022 http://www.medworm.com/index.php?rid=3362819&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20224956%26dopt%3DAbstract In this study we explored the use of coherence and Granger causality (GC) to separate patients in minimally conscious state (MCS) from patients with severe neurocognitive disorders (SND) that show signs of awareness. We studied 16 patients, 7 MCS and 9 SND with age between 18 and 49 years. Three minutes of ongoing electroencephalographic (EEG) activity was obtained at rest from 19 standard scalp locations, while subjects were alert but kept their eyes closed. GC was formulated in terms of linear autoregressive models that predict the evolution of several EEG time series, each representing the activity of one channel. The entire network of causally connected brain areas can be summarized as a graph of incompletely connected nodes. The 19 channels were grouped into five gross anatomical regi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3362819 Fri, 12 Mar 2010 00:00:00 +0100 3362819 http://www.medworm.com/index.php?rid=3336971&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20191316%26dopt%3DAbstract Authors: Blinowska K, Kus R, Kaminski M, Janiszewska J The transmission of brain activity during constant attention test was estimated by means of the short-time directed transfer function (SDTF). SDTF is an estimator based on a multivariate autoregressive model. It determines the propagation as a function of time and frequency. For nine healthy subjects the transmission of EEG activity was determined for target and non-target conditions corresponding to pressing of a switch in case of appearance of two identical images or withholding the reaction in case of different images. The involvement of prefrontal and frontal cortex manifested by the propagation from these structures was observed, especially in the early stages of the task. For the target condition there was a burst of propagat... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3336971 Sat, 27 Feb 2010 00:00:00 +0100 3336971 http://www.medworm.com/index.php?rid=3303329&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20177767%26dopt%3DAbstract Authors: Zhang J, Chen H, Fang F, Liao W The present study intends to quantitatively analyze power changes in blood oxygenation level-dependent (BOLD) signals, and to investigate functional asymmetry of cortical activity in motor areas during sequential finger movements. A power spectrum method was employed, mainly in contrast with the signal magnitude analysis, to investigate functional asymmetry of motor area cortical activity. Six right-handed subjects were included in the functional magnetic resonance imaging (fMRI) experiments. Both bi-handed and single-handed movements were analyzed. The power spectrum method demonstrated that right-handed subjects exhibited a larger power difference in BOLD signals between task and rest states in the right motor area than in the left motor area.... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3303329 Tue, 23 Feb 2010 00:00:00 +0100 3303329 http://www.medworm.com/index.php?rid=3285565&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162347%26dopt%3DAbstract Authors: Sannelli C, Dickhaus T, Halder S, Hammer EM, Müller KR, Blankertz B One crucial question in the design of electroencephalogram (EEG)-based brain-computer interface (BCI) experiments is the selection of EEG channels. While a setup with few channels is more convenient and requires less preparation time, a dense placement of electrodes provides more detailed information and henceforth could lead to a better classification performance. Here, we investigate this question for a specific setting: a BCI that uses the popular CSP algorithm in order to classify voluntary modulations of sensorimotor rhythms (SMR). In a first approach 13 different fixed channel configurations are compared to the full one consisting of 119 channels. The configuration with 48 channels results to be the... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3285565 Wed, 17 Feb 2010 00:00:00 +0100 3285565 http://www.medworm.com/index.php?rid=3270035&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20151193%26dopt%3DAbstract This study investigates the relationship between the estimated sources of MEG spikes and the location, distribution and size of interictal spikes in the invasive ECoG of a group of 38 epilepsy patients that are monitored for pre-surgical evaluation. An amplitude/surface area measure is defined to quantify and rank ECoG spikes. It is found that all MEG spikes are associated with an ECoG spike that is among the three highest ranked in a patient. Among the different brain regions considered, the fronto-orbital, inter-hemispheric, tempero-lateral and central regions stand out. In an accompanying simulation study it is shown that for hypothesized extended sources of larger sizes, as suggested by the data, source location, orientation and curvature can partly explain the observed sensitivity of ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3270035 Fri, 12 Feb 2010 00:00:00 +0100 3270035 http://www.medworm.com/index.php?rid=3201197&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20094766%26dopt%3DAbstract Authors: De Vico Fallani F, Maglione A, Babiloni F, Mattia D, Astolfi L, Vecchiato G, De Rinaldis A, Salinari S, Pachou E, Micheloyannis S In the present study, we studied the structural changes of the brain functional network in a group of schizophrenic (SCHZ) patients during a 2-back working memory task. Cortical signals were obtained from scalp EEG signals through the high-resolution EEG technique, which relies on realistic head models and linear inverse solutions. Functional networks were estimated by computing the spectral coherence-i.e. a measure of synchronization in the frequency domain-between the time series of all the available cortical sources. To analyze those cortical networks we followed a theoretical graph approach by computing the network density as the total number of... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3201197 Fri, 22 Jan 2010 00:00:00 +0100 3201197 http://www.medworm.com/index.php?rid=3149396&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20052528%26dopt%3DAbstract Authors: Mantini D, Marzetti L, Corbetta M, Romani GL, Del Gratta C Two major non-invasive brain mapping techniques, electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), have complementary advantages with regard to their spatial and temporal resolution. We propose an approach based on the integration of EEG and fMRI, enabling the EEG temporal dynamics of information processing to be characterized within spatially well-defined fMRI large-scale networks. First, the fMRI data are decomposed into networks by means of spatial independent component analysis (sICA), and those associated with intrinsic activity and/or responding to task performance are selected using information from the related time-courses. Next, the EEG data over all sensors are averaged with respe... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3149396 Wed, 06 Jan 2010 00:00:00 +0100 3149396 http://www.medworm.com/index.php?rid=3135933&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20043238%26dopt%3DAbstract Authors: Thut G, Pascual-Leone A PMID: 20043238 [PubMed - in process] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=3135933 Fri, 01 Jan 2010 00:00:00 +0100 3135933 http://www.medworm.com/index.php?rid=3135934&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20043199%26dopt%3DAbstract Authors: Lithari C, Frantzidis CA, Papadelis C, Vivas AB, Klados MA, Kourtidou-Papadeli C, Pappas C, Ioannides AA, Bamidis PD Men and women seem to process emotions and react to them differently. Yet, few neurophysiological studies have systematically investigated gender differences in emotional processing. Here, we studied gender differences using Event Related Potentials (ERPs) and Skin Conductance Responses (SCR) recorded from participants who passively viewed emotional pictures selected from the International Affective Picture System (IAPS). The arousal and valence dimension of the stimuli were manipulated orthogonally. The peak amplitude and peak latency of ERP components and SCR were analyzed separately, and the scalp topographies of significant ERP differences were documented. F... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3135934 Thu, 31 Dec 2009 00:00:00 +0100 3135934 http://www.medworm.com/index.php?rid=3130209&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20039116%26dopt%3DAbstract Authors: Gao JF, Yang Y, Lin P, Wang P, Zheng CX Frequent occurrence of electrooculography (EOG) artifacts leads to serious problems in interpreting and analyzing the electroencephalogram (EEG). In this paper, a robust method is presented to automatically eliminate eye-movement and eye-blink artifacts from EEG signals. Independent Component Analysis (ICA) is used to decompose EEG signals into independent components. Moreover, the features of topographies and power spectral densities of those components are extracted to identify eye-movement artifact components, and a support vector machine (SVM) classifier is adopted because it has higher performance than several other classifiers. The classification results show that feature-extraction methods are unsuitable for identifying eye-blink ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3130209 Tue, 29 Dec 2009 00:00:00 +0100 3130209 http://www.medworm.com/index.php?rid=3120652&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20033272%26dopt%3DAbstract In conclusion, the TV commercials proposed to the population analyzed have increased the HR values and the cerebral activity mainly in the theta band in the left hemisphere when they will be memorized and judged pleasant. Further research with an extended set of subjects will be necessary to further validate the observations reported in this paper. However, these conclusions seems reasonable and well inserted in the already existing literature on this topic related to the HERA model. PMID: 20033272 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=3120652 Tue, 22 Dec 2009 00:00:00 +0100 3120652 http://www.medworm.com/index.php?rid=3105664&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20020193%26dopt%3DAbstract This study demonstrates the feasibility of reducing the saccade linked gamma band artefact. PMID: 20020193 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=3105664 Fri, 18 Dec 2009 00:00:00 +0100 3105664 http://www.medworm.com/index.php?rid=3061758&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19960364%26dopt%3DAbstract In this study, we recorded high-density evoked potentials in 12 healthy control subjects and 11 amnesic patients with various types of brain damage affecting the medial temporal lobes, diencephalic structures, or both. Subjects performed a continuous recognition task composed of meaningful designs. Using whole-scalp spatiotemporal mapping techniques, we found that, during the first 200 ms following picture presentation, map configuration of amnesics and controls were indistinguishable. Beyond this period, processing significantly differed. Between 200 and 350 ms, amnesic patients expressed different topographical maps than controls in response to new and repeated pictures. From 350 to 550 ms, healthy subjects showed modulation of the same maps in response to new and repeated items. In amne... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3061758 Fri, 04 Dec 2009 00:00:00 +0100 3061758 http://www.medworm.com/index.php?rid=3041667&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19946737%26dopt%3DAbstract Authors: Vidaurre C, Blankertz B Brain-Computer Interfaces (BCIs) allow a user to control a computer application by brain activity as acquired, e.g., by EEG. One of the biggest challenges in BCI research is to understand and solve the problem of "BCI Illiteracy", which is that BCI control does not work for a non-negligible portion of users (estimated 15 to 30%). Here, we investigate the illiteracy problem in BCI systems which are based on the modulation of sensorimotor rhythms. In this paper, a sophisticated adaptation scheme is presented which guides the user from an initial subject-independent classifier that operates on simple features to a subject-optimized state-of-the-art classifier within one session while the user interacts the whole time with the same feedback application. Whi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3041667 Sat, 28 Nov 2009 00:00:00 +0100 3041667 http://www.medworm.com/index.php?rid=3037137&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19943100%26dopt%3DAbstract Authors: Huang MX, Lee RR, Gaa KM, Song T, Harrington DL, Loh C, Theilmann RJ, Edgar JC, Miller GA, Canive JM, Granholm E Although impairments related to somatosensory perception are common in schizophrenia, they have rarely been examined in functional imaging studies. In the present study, magnetoencephalography (MEG) was used to identify neural networks that support attention to somatosensory stimuli in healthy adults and abnormalities in these networks in patient with schizophrenia. A median-nerve oddball task was used to probe attention to somatosensory stimuli, and an advanced, high-resolution MEG source-imaging method was applied to assess activity throughout the brain. In nineteen healthy subjects, attention-related activation was seen in a sensorimotor network involving primary... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3037137 Fri, 27 Nov 2009 00:00:00 +0100 3037137 http://www.medworm.com/index.php?rid=3037136&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19943101%26dopt%3DAbstract Authors: Vrba J, Taulu S, Nenonen J, Ahonen A We have combined Signal Space Separation and beamformers (SSS beamformer). The SSS beamformer was tested by simulation in the presence of simulated brain noise. The SSS beamformer performs at least as well as the conventional beamformer, provided that the expansion order is sufficiently high. For beamformer outputs which depend on power or power difference normalized by the projected noise, the spatial resolution of the SSS beamformer is significantly better than that of the conventional beamformers if the sources are deeper, and about the same as that of the conventional beamformer when the sources are superficial. For beamformer outputs which depend on the ratio of powers, the spatial resolutions of the SSS and conventional beamfomers are... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3037136 Fri, 27 Nov 2009 00:00:00 +0100 3037136 http://www.medworm.com/index.php?rid=3037135&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19943102%26dopt%3DAbstract Authors: Koles ZJ, Lind JC, Flor-Henry P This is a quantitative EEG study of gender-related differences in brain function. It is novel in that to elicit gender differences, it was necessary to apply a spatial filter to the EEGs that was effective for suppressing components common to different cognitive states. The study involved estimates of both the source-current power density in the brain and the complex coherence between different regions in the brain, the latter probably unique in EEG source analysis. Gender effects are shown in terms of differences in both lateralized source power and complex coherence in response to verbal and spatial cognitive challenges. The results provide evidence that verbal and spatial challenges are more lateralized in males than in females, that females ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3037135 Fri, 27 Nov 2009 00:00:00 +0100 3037135 http://www.medworm.com/index.php?rid=3009310&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19921416%26dopt%3DAbstract In this study we used EEG-fMRI to determine the possible correlation between topographical movement-related EEG changes in brain oscillatory activity recorded from EEG electrodes over the scalp and fMRI cortical responses in motor areas during finger movement. Thirty-two channels of EEG were recorded in 12 subjects during eyes-closed condition inside a three T magnetic resonance (MR) scanner using an MR-compatible EEG recording system. Off-line MRI artifact subtraction software was applied to obtain continuous EEG data during fMRI acquisition. For EEG data analysis we used a time-frequency approach to measure time by varying the energy in a signal at a given frequency band by the convolution of the EEG signal with a wavelet family in the alpha and beta bands. The correlation between the BO... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3009310 Wed, 18 Nov 2009 00:00:00 +0100 3009310 http://www.medworm.com/index.php?rid=3009309&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19921417%26dopt%3DAbstract Authors: Rotenberg A Recent advances in methods for transcranial magnetic stimulation (TMS) enable its coupling to real-time EEG (TMS-EEG). Although TMS-EEG is applied largely in neurophysiology research, there are prospects for its use in clinical TMS practice, particularly in epilepsy where EEG is already in wide use, and where TMS is emerging as a diagnostic and therapeutic tool. In diagnostic applications, TMS-EEG may provide a useful measure of cortical excitability at baseline or after antiepileptic treatment. For therapeutic purposes, TMS-EEG may be of use in selection of appropriate TMS strength outside of the motor cortex where the threshold for cortical activation is more apparent with the aid of EEG. In other realistic clinical applications, TMS-EEG may be of use in real-tim... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3009309 Tue, 17 Nov 2009 00:00:00 +0100 3009309 http://www.medworm.com/index.php?rid=3003419&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19915972%26dopt%3DAbstract Authors: Johnson JS, Hamidi M, Postle BR A commonly held view is that, when delivered during the performance of a task, repetitive TMS (rTMS) influences behavior by producing transient "virtual lesions" in targeted tissue. However, findings of rTMS-related improvements in performance are difficult to reconcile with this assumption. With regard to the mechanism whereby rTMS influences concurrent task performance, a combined rTMS/EEG study conducted in our lab has revealed a complex set of relations between rTMS, EEG activity, and behavioral performance, with the effects of rTMS on power in the alpha band and on alpha:gamma phase synchrony each predicting its effect on behavior. These findings suggest that rTMS influences performance by biasing endogenous task-related oscillatory dynamic... Brain Topography journals http://www.medworm.com/rss/comments.php?id=3003419 Sat, 14 Nov 2009 00:00:00 +0100 3003419 http://www.medworm.com/index.php?rid=2836087&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19779823%26dopt%3DAbstract We report high relatedness/similarity estimates for fraternal siblings concordant for TS (r = 0.86-0.60) in the middle frontal-motor/cingulate/insular cortices. Regression analysis revealed significant negative correlations in the right insula with the YGTSS (r = -0.41, F = 6.09, P < 0.02) and the left cingulated cortex with the (CY-BOCS) (r = -0.35, F = 4.30, P < 0.05). Since previous findings have concluded that normal fraternal siblings are less alike in frontal cortices, the present findings may be attributed to TS. We speculate that the high ICC between siblings and the negative correlation between TS symptoms severity and cortical thickness measurements are related to the disturbances in the maturation of the motor-cingulate-insular cortical neural system that mediate self-regu... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2836087 Sun, 27 Sep 2009 18:28:05 +0100 2836087 http://www.medworm.com/index.php?rid=2742242&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19711180%26dopt%3DAbstract Authors: Toth M, Faludi B, Wackermann J, Czopf J, Kondakor I EEG background activity of patients with obstructive sleep apnea syndrome (OSAS, N = 25) was compared to that of normal controls (N = 14) to reflect alterations of brain electrical activity caused by chronic intermittent hypoxia in OSAS. Global and regional (left vs. right, anterior vs. posterior) measures of spatial complexity (Omega) were used to characterize the degree of spatial synchrony of EEG. Low resolution electromagnetic tomography (LORETA) was used to localize generators of EEG activity in separate frequency bands. Comparing patients to controls, lower Omega complexity was found globally and in the right hemisphere. Using LORETA, an increased medium frequency activity was seen bilaterally in the precuneus, paracent... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2742242 Wed, 26 Aug 2009 23:00:00 +0100 2742242 http://www.medworm.com/index.php?rid=2736608&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19705276%26dopt%3DAbstract Authors: Takeuchi M, Hori E, Takamoto K, Tran AH, Satoru K, Ishikawa A, Ono T, Endo S, Nishijo H To investigate relationships between hemodynamic responses and neural activities in the somatosensory cortices, hemodynamic responses by near infrared spectroscopy (NIRS) and electroencephalograms (EEGs) were recorded simultaneously while subjects received electrical stimulation in the right median nerve. The statistical significance of the hemodynamic responses was evaluated by a general linear model (GLM) with the boxcar design matrix convoluted with Gaussian function. The resulting NIRS and EEGs data were stereotaxically superimposed on the reconstructed brain of each subject. The NIRS data indicated that changes in oxy-hemoglobin concentration increased at the contralateral primary soma... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2736608 Mon, 24 Aug 2009 23:00:00 +0100 2736608 http://www.medworm.com/index.php?rid=2730655&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19701702%26dopt%3DAbstract This study provides results to support the notion that deviations in cognitive function(s) attributed to the auditory P50 in adults might involve abnormalities in neuronal activity of the frontal lobe or in the interaction between the frontal and temporal lobes. Validation and localisation of progenitors of the adults' P50 in young children is a much-needed step in the understanding of the biological significance of different subcomponents that comprise the auditory P50 in the adult brain. In combination with other approaches investigating neuronal mechanisms of auditory P50, the present results contribute to the greater understanding of what and why neuronal activity underlying this response is aberrant in a number of brain dysfunctions. Moreover, the present source localisation results o... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2730655 Fri, 21 Aug 2009 23:00:00 +0100 2730655 http://www.medworm.com/index.php?rid=2675453&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19653090%26dopt%3DAbstract Authors: Tei S, Faber PL, Lehmann D, Tsujiuchi T, Kumano H, Pascual-Marqui RD, Gianotti LR, Kochi K Many meditation exercises aim at increased awareness of ongoing experiences through sustained attention and at detachment, i.e., non-engaging observation of these ongoing experiences by the intent not to analyze, judge or expect anything. Long-term meditation practice is believed to generalize the ability of increased awareness and greater detachment into everyday life. We hypothesized that neuroplasticity effects of meditation (correlates of increased awareness and detachment) would be detectable in a no-task resting state. EEG recorded during resting was compared between Qigong meditators and controls. Using LORETA (low resolution electromagnetic tomography) to compute the intracerebra... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2675453 Mon, 03 Aug 2009 23:00:00 +0100 2675453 http://www.medworm.com/index.php?rid=2675452&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19653091%26dopt%3DAbstract This study examined the brain electrical activity changes in 26 participants (14 males M = 21.64, SD = 3.99; 12 females M = 24.42, SD = 4.36), during a passive face viewing task, a scrambled face task and separate emotion and gender face discrimination tasks. The steady state visual evoked potential (SSVEP) was recorded from 64-electrode sites. Consistent with previous research, face related activity was evidenced at scalp regions over the parieto-temporal region approximately 170 ms after stimulus presentation. Results also identified different SSVEP spatio-temporal changes associated with the processing of static and dynamic facial emotions with respect to gender, with static stimuli predominately associated with an increase in inhibitory processing within the frontal region. Dynamic fac... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2675452 Mon, 03 Aug 2009 23:00:00 +0100 2675452 http://www.medworm.com/index.php?rid=2550472&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19557510%26dopt%3DAbstract Authors: Ramon C, Freeman WJ, Holmes M, Ishimaru A, Haueisen J, Schimpf PH, Rezvanian E Electrical dipoles oriented perpendicular to the cortical surface are the primary source of the scalp EEGs and MEGs. Thus, in particular, gyri and sulci structures on the cortical surface have a definite possibility to influence the EEGs and MEGs. This was examined by comparing the spatial power spectral density (PSD) of the upper portion of the human cortex in MRI slices to that of simulated scalp EEGs and MEGs. The electrical activity was modeled with 2,650 dipolar sources oriented normal to the local cortical surface. The resulting scalp potentials were calculated with a finite element model of the head constructed from 51 segmented sagittal MR images. The PSD was computed after taking the fast F... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2550472 Thu, 25 Jun 2009 23:00:00 +0100 2550472 http://www.medworm.com/index.php?rid=2525482&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19499197%26dopt%3DAbstract In this study, co-registration of Transcranial Magnetic Stimulation (TMS) and Electroencephalographic activity (EEG) has been used to investigate the spreading of cortical connections from the parietal cortex in healthy volunteers. TMS on the left parietal cortex activated a network of prefrontal regions in the contra-lateral hemisphere in a time range of 102-167 ms after the stimulus. Moreover, activation in the ipsi-lateral middle temporal and fusiform gyri was observed at 171-177 ms after delivery of TMS. Findings suggest the existence of late driven connections between parietal and prefrontal regions that could partially represent the neural pathway related to attention, even if, in this experiment, no attentional processing was requested. Late connections between dorsal and ventral st... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525482 Thu, 04 Jun 2009 23:00:00 +0100 2525482 http://www.medworm.com/index.php?rid=2525484&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19455411%26dopt%3DAbstract This study revealed the possibility that the left sensorimotor cortex was more closely involved in non-verbal mouth movement in men, suggesting sex-related differences in sensorimotor cortex activation. PMID: 19455411 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525484 Tue, 19 May 2009 23:00:00 +0100 2525484 http://www.medworm.com/index.php?rid=2525486&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19452270%26dopt%3DAbstract Authors: Foxe JJ, Molholm S PMID: 19452270 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525486 Mon, 18 May 2009 23:00:00 +0100 2525486 http://www.medworm.com/index.php?rid=2525490&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19415481%26dopt%3DAbstract Authors: Hugenschmidt CE, Mozolic JL, Tan H, Kraft RA, Laurienti PJ Behavioral research indicates that healthy aging is accompanied by maintenance of voluntary attentional function in many situations, suggesting older adults are able to use attention to enhance and suppress neural activity. However, other experiments show increased distractibility with age, suggesting a failure of attention. One hypothesis for these apparently conflicting findings is that older adults experience a greater sensory processing load at baseline compared to younger adults. In this situation, older adults might successfully modulate sensory cortical activity relative to a baseline referent condition, but the increased baseline load results in more activity than younger adults after attentional modulation. Th... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525490 Mon, 04 May 2009 23:00:00 +0100 2525490 http://www.medworm.com/index.php?rid=2525488&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19415482%26dopt%3DAbstract Authors: Vroomen J, de Gelder B PMID: 19415482 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525488 Mon, 04 May 2009 23:00:00 +0100 2525488 http://www.medworm.com/index.php?rid=2525492&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19408112%26dopt%3DAbstract Authors: Zhong Y, Wang H, Lu G, Zhang Z, Jiao Q, Liu Y A fMRI connectivity analysis approach combining principal component analysis (PCA) and regression analysis is proposed to detect functional connectivity between the brain regions. By first using PCA to identify clusters within the vectors of fMRI time series, more energy and information features in the signal can be maintained than using averaged values from brain regions of interest. Then, regression analysis can be applied to the extracted principal components in order to further investigate functional connectivity. Finally, t-test is applied and the patterns with t-values lager than a threshold are considered as functional connectivity mappings. The validity and reliability of the presented method were demonstrated with both sim... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525492 Thu, 30 Apr 2009 23:00:00 +0100 2525492 http://www.medworm.com/index.php?rid=2525494&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19404730%26dopt%3DAbstract Authors: Ponton CW, Bernstein LE, Auer ET The functional organization of cortical speech processing is thought to be hierarchical, increasing in complexity and proceeding from primary sensory areas centrifugally. The current study used the mismatch negativity (MMN) obtained with electrophysiology (EEG) to investigate the early latency period of visual speech processing under both visual-only (VO) and audiovisual (AV) conditions. Current density reconstruction (CDR) methods were used to model the cortical MMN generator locations. MMNs were obtained with VO and AV speech stimuli at early latencies (approximately 82-87 ms peak in time waveforms relative to the acoustic onset) and in regions of the right lateral temporal and parietal cortices. Latencies were consistent with bottom-up proce... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525494 Wed, 29 Apr 2009 23:00:00 +0100 2525494 http://www.medworm.com/index.php?rid=2525498&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19404728%26dopt%3DAbstract Authors: Holmes NP The principle of inverse effectiveness (PoIE) in multisensory integration states that, as the responsiveness to individual sensory stimuli decreases, the strength of multisensory integration increases. I discuss three potential problems in the analysis of multisensory data with regard to the PoIE. First, due to 'regression towards the mean,' the PoIE may often be observed in datasets that are analysed post-hoc (i.e., when sorting the data by the unisensory responses). The solution is to design discrete levels of stimulus intensity a priori. Second, due to neurophysiological or methodological constraints on responsiveness, the PoIE may be, in part, a consequence of 'floor' and 'ceiling' effects. The solution is to avoid analysing or interpreting data that are too clos... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525498 Tue, 28 Apr 2009 23:00:00 +0100 2525498 http://www.medworm.com/index.php?rid=2525496&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19404729%26dopt%3DAbstract In this study, we examined event-related potentials (ERPs) elicited by laser dots projected onto or above participants' index and middle fingers during a sustained-attention task. We hypothesized that visual stimuli projected onto the hand would elicit differences in ERP deflections related to sensory gating and categorization in comparison to when projected close to the hand. Participants responded via a footswitch to rare target flashes of light occurring on or directly above the middle finger of the attended hand. We found enhanced amplitudes of the N1 and P3 deflections when the stimuli fell onto the finger tips as opposed to above them. Furthermore, the N1 for unattended stimuli was less suppressed when the lasers were projected onto the fingers. Behaviorally, participants were less a... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525496 Tue, 28 Apr 2009 23:00:00 +0100 2525496 http://www.medworm.com/index.php?rid=2525502&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19384602%26dopt%3DAbstract Authors: Brefczynski-Lewis J, Lowitszch S, Parsons M, Lemieux S, Puce A In an everyday social interaction we automatically integrate another's facial movements and vocalizations, be they linguistic or otherwise. This requires audiovisual integration of a continual barrage of sensory input-a phenomenon previously well-studied with human audiovisual speech, but not with non-verbal vocalizations. Using both fMRI and ERPs, we assessed neural activity to viewing and listening to an animated female face producing non-verbal, human vocalizations (i.e. coughing, sneezing) under audio-only (AUD), visual-only (VIS) and audiovisual (AV) stimulus conditions, alternating with Rest (R). Underadditive effects occurred in regions dominant for sensory processing, which showed AV activation greater than... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525502 Wed, 22 Apr 2009 23:00:00 +0100 2525502 http://www.medworm.com/index.php?rid=2525500&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19387818%26dopt%3DAbstract Authors: Cardinali L, Brozzoli C, Farnè A To sensibly interact with the environment, like when grasping objects and navigating through space, the brain needs to compute not only target- and environment-related inputs, but also the size and spatial location of the entire body as well as of its parts. The neuronal construction and dynamic updating throughout the entire life of this bodily representation, commonly termed body schema in the literature, appears essential for efficient motor control and skilful tool-use. Meanwhile, recent contributions to the study of spatial multisensory processing have identified the peripersonal space as a particular region surrounding the body that acts as an interface between the body and the environment, for defensive and/or purposeful actions tow... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2525500 Wed, 22 Apr 2009 23:00:00 +0100 2525500 http://www.medworm.com/index.php?rid=2300749&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19337824%26dopt%3DAbstract Authors: Colonius H, Diederich A, Steenken R Saccadic reaction time (SRT) to a visual target tends to be shorter when auditory stimuli are presented in close temporal and spatial proximity, even when subjects are instructed to ignore the auditory non-target (focused attention paradigm). Previous studies using pairs of visual and auditory stimuli differing in both azimuth and vertical position suggest that the amount of SRT facilitation decreases not with the physical but with the perceivable distance between visual target and auditory non-target. Steenken et al. (Brain Res 1220:150-156, 2008) presented an additional white-noise masker background of three seconds duration. Increasing the masker level had a diametrical effect on SRTs in spatially coincident versus disparate stimulus conf... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2300749 Wed, 01 Apr 2009 04:00:00 +0100 2300749 http://www.medworm.com/index.php?rid=2300750&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19330441%26dopt%3DAbstract Authors: Lacey S, Tal N, Amedi A, Sathian K This review surveys the recent literature on visuo-haptic convergence in the perception of object form, with particular reference to the lateral occipital complex (LOC) and the intraparietal sulcus (IPS) and discusses how visual imagery or multisensory representations might underlie this convergence. Drawing on a recent distinction between object- and spatially-based visual imagery, we propose a putative model in which LOtv, a subregion of LOC, contains a modality-independent representation of geometric shape that can be accessed either bottom-up from direct sensory inputs or top-down from frontoparietal regions. We suggest that such access is modulated by object familiarity: spatial imagery may be more important for unfamiliar objects and in... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2300750 Sat, 28 Mar 2009 04:00:00 +0100 2300750 http://www.medworm.com/index.php?rid=2300752&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19326203%26dopt%3DAbstract Authors: Azulay H, Striem E, Amedi A People tend to close their eyes when trying to retrieve an event or a visual image from memory. However the brain mechanisms behind this phenomenon remain poorly understood. Recently, we showed that during visual mental imagery, auditory areas show a much more robust deactivation than during visual perception. Here we ask whether this is a special case of a more general phenomenon involving retrieval of intrinsic, internally stored information, which would result in crossmodal deactivations in other sensory cortices which are irrelevant to the task at hand. To test this hypothesis, a group of 9 sighted individuals were scanned while performing a memory retrieval task for highly abstract words (i.e., with low imaginability scores). We also scanned a ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2300752 Fri, 27 Mar 2009 04:00:00 +0100 2300752 http://www.medworm.com/index.php?rid=2300751&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19326204%26dopt%3DAbstract Authors: Allman BL, Keniston LP, Meredith MA Traditionally, neuronal studies of multisensory processing proceeded by first identifying neurons that were overtly multisensory (e.g., bimodal, trimodal) and then testing them. In contrast, the present study examined, without precondition, neurons in an extrastriate visual area of the cat for their responses to separate (visual, auditory) and combined-modality (visual and auditory) stimulation. As expected, traditional bimodal forms of multisensory neurons were identified. In addition, however, many neurons that were activated only by visual stimulation (i.e., unimodal) had that response modulated by the presence of an auditory stimulus. Some unimodal neurons showed multisensory responses that were statistically different from their visual ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2300751 Fri, 27 Mar 2009 04:00:00 +0100 2300751 http://www.medworm.com/index.php?rid=2300753&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19322649%26dopt%3DAbstract Authors: Corrigan NM, Richards T, Webb SJ, Murias M, Merkle K, Kleinhans NM, Johnson LC, Poliakov A, Aylward E, Dawson G Brain activity patterns during face processing have been extensively explored with functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs). ERP source localization adds a spatial dimension to the ERP time series recordings, which allows for a more direct comparison and integration with fMRI findings. The goals for this study were (1) to compare the spatial descriptions of neuronal activity during face processing obtained with fMRI and ERP source localization using low-resolution electromagnetic tomography (LORETA), and (2) to use the combined information from source localization and fMRI to explore how the temporal sequence of brain activity ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2300753 Thu, 26 Mar 2009 04:00:00 +0100 2300753 http://www.medworm.com/index.php?rid=2275003&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19288184%26dopt%3DAbstract This article highlights current hypotheses regarding the mechanisms of action of TBS and some central factors which may influence cortical responses to TBS. Furthermore, previous and ongoing research performed in the field of TBS on the motor cortex is summarized. PMID: 19288184 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=2275003 Sat, 14 Mar 2009 04:00:00 +0100 2275003 http://www.medworm.com/index.php?rid=2242663&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19266276%26dopt%3DAbstract Authors: Zaehle T, Jancke L, Herrmann CS, Meyer M In the present study, we investigated the pre-attentive processing of low-level acoustic properties and the impact of this mechanism on functional lateralization in the human auditory system. Mismatch negativity (MMN) of the event-related potentials (ERP) were recorded in 19 adult humans who passively listened to a standard stimulus and spectrally and temporally deviant sounds. We predicted modulations of the MMN amplitude in response to spectrally and temporally graded deviants. Based on recent models of functional hemispheric lateralisation, we further hypothesized a left-lateralized source of the MMN in response to temporal deviants and, in contrast, a right-lateralized source of the MMN in response to spectral deviants. In agreement... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2242663 Fri, 06 Mar 2009 05:00:00 +0100 2242663 http://www.medworm.com/index.php?rid=2218316&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19241152%26dopt%3DAbstract Authors: Miniussi C, Thut G The combination of brain stimulation by transcranial magnetic stimulation (TMS) with simultaneous electroencephalographic (EEG) imaging has become feasible due to recent technical developments. The TMS-EEG integration provides real-time information on cortical reactivity and connectivity through the analysis of TMS-evoked potentials (TEPs), and how functional activity links to behavior through the study of TMS-induced modulations thereof. It reveals how these effects vary as a function of neuronal state, differing between individuals and patient groups but also changing rapidly over time during task performance. This review discusses the wide range of possible TMS-EEG applications and what new information may be gained using this technique on the dynamics of... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2218316 Wed, 25 Feb 2009 05:00:00 +0100 2218316 http://www.medworm.com/index.php?rid=2212457&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19234780%26dopt%3DAbstract Authors: Jerbi K, Freyermuth S, Dalal S, Kahane P, Bertrand O, Berthoz A, Lachaux JP Recent evidence suggests that transient increases in scalp electroencephalography (EEG) gamma band power (above 30 Hz) can be due to miniature eye movements. Although, these findings do not raise doubts about the widely established role of gamma range neural synchrony, it does call for caution when it comes to interpreting high frequency scalp EEG data. By contrast, gamma-band activity detected with intracerebral EEG (iEEG) is assumed to be immune to such miniature saccade artefacts. Here, we show for the first time, that while this is indeed largely the case, intracerebral recordings in the temporal pole of implanted patients can be contaminated by saccadic eye muscle artefacts resulting in typical hi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2212457 Sat, 21 Feb 2009 05:00:00 +0100 2212457 http://www.medworm.com/index.php?rid=2212456&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19234781%26dopt%3DAbstract Authors: Yuval-Greenberg S, Deouell LY The contraction of the extra-ocular muscles, during the execution of saccades, produces a strong electric potential in the EEG called the saccadic spike potential (SP). At the frequency spectrum, this SP manifests as a broadband response with most of its power at the gamma-band frequencies. Saccadic activity is known to follow a time-pattern of repression (at around 50-150 ms post stimulus) which is followed by a large increase in saccadic rate at around 200-300 ms post stimulus. Due to this temporal pattern relative to the stimulus, and to the appearance of a SP at each saccade, this increase in saccadic rate shows up after averaging as an increase in gamma-band activity at the time-range of 200-300 ms. Thus, the broadband-transient "induced gamm... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2212456 Sat, 21 Feb 2009 05:00:00 +0100 2212456 http://www.medworm.com/index.php?rid=2205809&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19229605%26dopt%3DAbstract Authors: Pope KJ, Fitzgibbon SP, Lewis TW, Whitham EM, Willoughby JO We recorded scalp electrical activity before and after full neuro-muscular paralysis in 5 volunteers and determined differences due to elimination of muscular activity on several standard applications of EEG. Due to paralysis, there were reductions in 'noisiness' of the standard scalp recordings which were maximal over the peripheral scalp, not explained by abolition of movement artefact, and best accounted for by sustained EMG activity in resting individuals. There was a corresponding reduction in spectral power in the gamma range. In central leads, the extent of gamma frequency coherence during a non-time-locked mental task (1 s epochs) was reduced by paralysis, likely due to a reduction in gamma-frequency coherence... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2205809 Fri, 20 Feb 2009 05:00:00 +0100 2205809 http://www.medworm.com/index.php?rid=2188646&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19214730%26dopt%3DAbstract Authors: Shackman AJ, McMenamin BW, Slagter HA, Maxwell JS, Greischar LL, Davidson RJ Muscle or electromyogenic (EMG) artifact poses a serious risk to inferential validity for any electroencephalography (EEG) investigation in the frequency-domain owing to its high amplitude, broad spectrum, and sensitivity to psychological processes of interest. Even weak EMG is detectable across the scalp in frequencies as low as the alpha band. Given these hazards, there is substantial interest in developing EMG correction tools. Unfortunately, most published techniques are subjected to only modest validation attempts, rendering their utility questionable. We review recent work by our laboratory quantitatively investigating the validity of two popular EMG correction techniques, one using the general ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2188646 Thu, 12 Feb 2009 05:00:00 +0100 2188646 http://www.medworm.com/index.php?rid=2184709&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19212812%26dopt%3DAbstract Authors: Michel CM, Murray MM PMID: 19212812 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=2184709 Wed, 11 Feb 2009 05:00:00 +0100 2184709 http://www.medworm.com/index.php?rid=2184711&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19205863%26dopt%3DAbstract Authors: Schroeder CE, Lakatos P The idea that gamma enhancement reflects a state of high neuronal excitability and synchrony, critical for active brain operations, sets gamma up as a "master" or executor process that determines whether an input is effectively integrated and an effective output is generated. However, gamma amplitude is often coupled to the phase of lower frequency delta or theta oscillations, which would make gamma a "slave" to lower frequency activity. Gamma enslavement is productive and typical during rhythmic mode brain operations; when a predictable rhythm is in play, low and mid-frequency oscillations can be entrained and their excitability fluctuations of put to work in sensory and motor functions. When there is no task relevant rhythm that the system can entrain... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2184711 Tue, 10 Feb 2009 05:00:00 +0100 2184711 http://www.medworm.com/index.php?rid=2174927&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19199019%26dopt%3DAbstract Authors: Ohla K, Hudry J, le Coutre J Electrogustometry (EGM) is the standard tool to assess gustatory functions in clinical environments. The stimulation elicits a percept often described as metallic, sour or salty, also referred to as electric taste. To date, the neuronal mechanisms that underlie electric taste perception are not yet fully understood. Electroencephalographic (EEG) approaches will certainly complement behavioral procedures and, furthermore, extend the understanding of gustatory processing in general and disturbances of gustatory functions in particular. We used anodal pulses applied to the tip of the participants' tongue while EEG was recorded. The major disadvantage of combining EEG and EGM, namely the electrical stimulation artifact, was overcome by means of Indepen... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2174927 Fri, 06 Feb 2009 05:00:00 +0100 2174927 http://www.medworm.com/index.php?rid=2174926&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19199020%26dopt%3DAbstract Authors: Collignon O, Davare M, Olivier E, De Volder AG It is well known that, following an early visual deprivation, the neural network involved in processing auditory spatial information undergoes a profound reorganization. In particular, several studies have demonstrated an extensive activation of occipital brain areas, usually regarded as essentially "visual", when early blind subjects (EB) performed a task that requires spatial processing of sounds. However, little is known about the possible consequences of the activation of occipitals area on the function of the large cortical network known, in sighted subjects, to be involved in the processing of auditory spatial information. To address this issue, we used event-related transcranial magnetic stimulation (TMS) to induce virtual ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2174926 Fri, 06 Feb 2009 05:00:00 +0100 2174926 http://www.medworm.com/index.php?rid=2164489&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19194794%26dopt%3DAbstract Authors: Catena A, Houghton G, Valdés B, Fuentes LJ Masked priming experiments are frequently used to study automatic aspects of word processing. Direct measures of such processing obtained with functional neuroimaging techniques (ERPs, fMRI, etc.) need to isolate the neural activation related to relevant events when they are rapidly followed by others (a situation found in other popular paradigms such as the attentional blink and repetition blindness). Here we examine the assumption of "simple insertion", which underlies the use of subtraction to isolate components of temporally overlapping waveforms. We propose two novel linear methods and illustrate how they extract temporal and spatial ERP components that the subtraction method fails to detect. We show this through the analysi... Brain Topography journals http://www.medworm.com/rss/comments.php?id=2164489 Thu, 05 Feb 2009 05:00:00 +0100 2164489 http://www.medworm.com/index.php?rid=1981963&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19023662%26dopt%3DAbstract Authors: Whittingstall K, Wilson D, Schmidt M, Stroink G PMID: 19023662 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=1981963 Sun, 23 Nov 2008 15:30:48 +0100 1981963 http://www.medworm.com/index.php?rid=1962273&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19005748%26dopt%3DAbstract This study suggests a definition of SI that gives a semiautomatic and relatively robust algorithm for assessment. The method employs spike detection by means of template matching of the current source density estimate. The percentage of time within an epoch with interspike interval (ISI) below a given limit, usually 3 s, is returned as the SI. This is calculated during daytime and in non-REM sleep. The standard epoch length is 10 min. The parameter selection is discussed in the context of the influence of spikes and bursts on cognition. The described method gives reproducible results in routine use, gives clinical valuable information, and is easily implemented in a clinical setting. There is only a minor added workload for the electroencephalographer. PMID: 19005748 [PubMed - as suppl... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1962273 Thu, 13 Nov 2008 05:00:00 +0100 1962273 http://www.medworm.com/index.php?rid=1962272&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19005749%26dopt%3DAbstract Authors: Dimitriadis SI, Laskaris NA, Del Rio-Portilla Y, Koudounis GC Following a nonlinear dynamics approach, we investigated the emergence of functional clusters which are related with spontaneous brain activity during sleep. Based on multichannel EEG traces from 10 healthy subjects, we compared the functional connectivity across different sleep stages. Our exploration commences with the conjecture of a small-world patterning, present in the scalp topography of the measured electrical activity. The existence of such a communication pattern is first confirmed for our data and then precisely determined by means of two distinct measures of non-linear interdependence between time-series. A graph encapsulating the small-world network structure along with the relative interdependence stre... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1962272 Thu, 13 Nov 2008 05:00:00 +0100 1962272 http://www.medworm.com/index.php?rid=1926867&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18958615%26dopt%3DAbstract Authors: Korb AS, Cook IA, Hunter AM, Leuchter AF Many brain regions show metabolic and perfusion abnormalities in major depressive disorder (MDD), including anterior cingulate and prefrontal cortices. Some of these same areas also show abnormal function with low resolution electromagnetic tomography (LORETA). However, LORETA results are not always consistent across studies, nor with findings from other imaging modalities. These discrepancies may be due, among other factors, to the sensitivity of EEG source localization to different electrode montages. Thirty-six channel EEG was collected from healthy controls and age- and gender-matched unmedicated subjects with MDD (n = 74). EEGs were analyzed with LORETA to assess resting state current density at each of 2,394 cortical voxels. For c... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1926867 Wed, 29 Oct 2008 04:00:00 +0100 1926867 http://www.medworm.com/index.php?rid=1863644&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18841455%26dopt%3DAbstract In this study, we used a visual stimuli designed to shift cortical activity from anterior to posterior regions of the visual cortex. Using EEG and FMRI, we investigated how shifts in +BOLD and -BOLD location were correlated to shifts in the N75 and P100 visual evoked potential (VEP) dipolar sources. The results show that the N75 dipole along with +BOLD, were indeed shifted from posterior to anterior regions of the visual cortex. The P100 VEP component, along with the -BOLD were not shifted to the same extent, indicating that N75 is better correlated to +BOLD than to -BOLD. These findings indicate how different components of the EEG signal are related to the positive and negative BOLD responses, which may aid in interpreting the relationship between visually evoked EEG and FMRI signals. ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1863644 Thu, 09 Oct 2008 04:00:00 +0100 1863644 http://www.medworm.com/index.php?rid=1863643&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18841456%26dopt%3DAbstract Conclusions This pattern of results implies that L: -theanine plays a more general role in attentional processing, facilitating longer-lasting processes responsible for sustaining attention across the timeframe of a difficult task, rather than affecting specific moment-to-moment phasic deployment processes. PMID: 18841456 [PubMed - as supplied by publisher] (Source: Brain Topography) Brain Topography journals http://www.medworm.com/rss/comments.php?id=1863643 Thu, 09 Oct 2008 04:00:00 +0100 1863643 http://www.medworm.com/index.php?rid=1807087&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18800243%26dopt%3DAbstract Authors: Overney LS, Blanke O The brain processes associated with mental imagery have long been a matter of debate. Neuroimaging and neuropsychological studies have yielded diverging evidence of mental transformation activating the right hemisphere, the left hemisphere, or both. Here, using a mirror/normal discrimination task with rotated body parts (BPs) and external objects (EOs), we describe the case of a patient who developed a selective deficit in mental imagery of such BPs due to left posterior parietal brain damage. In addition, the patient's deficit predominated for pictures of right arms (i.e., arms corresponding to the patient's imagined contralesional arm) and was further characterised by an inability to distinguish between anatomically possible and impossible arm positions.... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1807087 Thu, 18 Sep 2008 04:00:00 +0100 1807087 http://www.medworm.com/index.php?rid=1795421&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18791818%26dopt%3DAbstract Authors: Silvanto J, Pascual-Leone A Transcranial magnetic stimulation (TMS), a tool that allows noninvasive modulation of cortical neural activity, has become an important tool in cognitive neuroscience and is being increasingly explored in neurotherapeutics. Amongst the factors that are likely to influence its efficacy, the importance of the baseline cortical activation state on the impact of TMS has not received much attention. However, this state-dependency is important as the neural impact of any external stimulus represents an interaction with the ongoing brain activity at the time of stimulation. The effects of any external stimulus are therefore not only determined by the properties of that stimulus but also by the activation state of the brain. Here we review the existing evid... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1795421 Sat, 13 Sep 2008 04:00:00 +0100 1795421 http://www.medworm.com/index.php?rid=1786703&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18784997%26dopt%3DAbstract Parvocellular and Magnocellular Contributions to the Initial Generators of the Visual Evoked Potential: High-Density Electrical Mapping of the "C1" Component. Brain Topogr. 2008 Sep 11; Authors: Foxe JJ, Strugstad EC, Sehatpour P, Molholm S, Pasieka W, Schroeder CE, McCourt ME The C1 component of the VEP is considered to index initial afference of retinotopic regions of human visual cortex (V1 and V2). C1 onsets over central parieto-occipital scalp between 45 and 60 ms, peaks between 70 and 100 ms, and then resolves into the following P1 component. By exploiting isoluminant and low-contrast luminance stimuli, we assessed the relative contributions of the Magnocellular (M) and Parvocellular (P) pathways to generation of C1. C1 was maximal at 88 ms in a 100% luminance contrast co... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1786703 Thu, 11 Sep 2008 04:00:00 +0100 1786703 http://www.medworm.com/index.php?rid=1780461&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18780176%26dopt%3DAbstract Authors: Holz EM, Doppelmayr M, Klimesch W, Sauseng P To investigate electrophysiological correlates of action observation electroencephalogram (EEG) was recorded while participants observed repetitive biological (human) or non-biological movements (at a rate of 2 Hz). Steady-state evoked potentials were analyzed and their neural sources were investigated using low resolution electromagnetic tomography analysis (LORETA). Results revealed significantly higher activation in the primary motor and premotor cortex, supplementary motor area as well as the posterior parietal cortices during observation of biological movements, supporting mirror properties of cortical motor neurons. In addition interregional communication was analyzed. Increased coherence for distributed networks at delta (0.5... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1780461 Tue, 09 Sep 2008 04:00:00 +0100 1780461 http://www.medworm.com/index.php?rid=1751824&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18758934%26dopt%3DAbstract Authors: Minati L, Rosazza C, Zucca I, D'Incerti L, Scaioli V, Bruzzone MG We investigated the spatial correspondence between functional MRI (fMRI) activations and cortical current density maps of event-related potentials (ERPs) reconstructed without fMRI priors. The presence of a significant spatial correspondence is a prerequisite for direct integration of the two modalities, enabling to combine the high spatial resolution of fMRI with the high temporal resolution of ERPs. Four separate tasks were employed: visual stimulation with a pattern-reversal chequerboard, recognition of images of nameable objects, recognition of written words, and auditory stimulation with a piano note. ERPs were acquired with 19 recording channels, and source localisation was performed using a realistic head... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1751824 Fri, 29 Aug 2008 04:00:00 +0100 1751824 http://www.medworm.com/index.php?rid=1744141&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18726681%26dopt%3DAbstract This study examined regional cortical activations and cortico-cortical connectivity in a group of 20 high-functioning patients with schizophrenia and 20 healthy controls matched for age and sex during a 0- and a 2-back working memory (WM) task. An earlier study comparing schizophrenia patients with education level-matched healthy controls revealed less "optimally" organized network during the 2-back task, whereas a second study with healthy volunteers had suggested that the degree of cortical organization may be inversely proportional to educational level (less optimal functional connectivity in better educated individuals interpreted as the result of higher efficiency). In the present study, both groups succeeded in the 2-back WM task although healthy individuals had generally attained a ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1744141 Tue, 26 Aug 2008 04:00:00 +0100 1744141 http://www.medworm.com/index.php?rid=1684173&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18679787%26dopt%3DAbstract Authors: Clemens B, Bánk J, Piros P, Bessenyei M, Vető S, Tóth M, Kondákor I Investigating the brain of migraine patients in the pain-free interval may shed light on the basic cerebral abnormality of migraine, in other words, the liability of the brain to generate migraine attacks from time to time. Twenty unmedicated "migraine without aura" patients and a matched group of healthy controls were investigated in this explorative study. 19-channel EEG was recorded against the linked ears reference and was on-line digitized. 60 x 2-s epochs of eyes-closed, waking-relaxed activity were subjected to spectral analysis and a source localization method, low resolution electromagnetic tomography (LORETA). Absolute power was computed for 19 electrodes and four frequency bands... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1684173 Tue, 05 Aug 2008 04:00:00 +0100 1684173 http://www.medworm.com/index.php?rid=1684172&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18679788%26dopt%3DAbstract Authors: Wang Y, Xiang J, Kotecha R, Vannest J, Liu Y, Rose D, Schapiro M, Degrauw T The present study investigated the spatial and frequency differences of neuromagnetic activities between the perception of open- and closed-class words by using a 275-channel whole head magnetoencephalography (MEG) system. Two groups of words, 110 open-class and 110 closed-class, were presented visually and auditorily simultaneously. The data of 12 healthy subjects were analyzed with synthetic aperture magnetometry (SAM) which can identify the frequency-dependent volumetric distribution of evoked magnetic fields (EMFs). Both vocabulary classes elicited spectral power changes in the left inferior frontal gyrus (Broca's area) and left posterior-superior temporal gyrus (Wernicke's area) within 70-120 Hz. ... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1684172 Tue, 05 Aug 2008 04:00:00 +0100 1684172 http://www.medworm.com/index.php?rid=1650251&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18648924%26dopt%3DAbstract In this study we used EEG-fMRI to determine the possible correlation between topographical movement-related EEG changes in brain oscillatory activity recorded from EEG electrodes over the scalp and fMRI-BOLD cortical responses in motor areas during finger movement. Thirty-two channels of EEG were recorded in 9 subjects during eyes-open condition inside a 1.5 T magnetic resonance (MR) scanner using a MR-compatible EEG recording system. Off-line MRI artifact subtraction software was applied to obtain continuous EEG data during fMRI acquisition. For EEG data analysis we used the event-related-synchronization/desynchronization (ERS/ERD) approach to investigate where movement-related decreases in alpha and beta power are located. For image statistical analysis we used a general linear model (GL... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1650251 Tue, 22 Jul 2008 04:00:00 +0100 1650251 http://www.medworm.com/index.php?rid=1632807&cid=s_37629_168_f&fid=37629&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18629625%26dopt%3DAbstract Authors: Chauveau N, Franceries X, Aubry F, Celsis P, Rigaud B The T1 head template model used in Statistical Parametric Mapping Version 2000 (SPM2), was segmented into five layers (scalp, skull, CSF, grey and white matter) and implemented in 2 mm voxels. We designed a resistor mesh model (RMM), based on the finite volume method (FVM) to simulate the electrical properties of this head model along the three axes for each voxel. Then, we introduced four dipoles of high eccentricity (about 0.8) in this RMM, separately and simultaneously, to compute the potentials for two sets of conductivities. We used the direct cortical imaging technique (CIT) to recover the simulated dipoles, using 60 or 107 electrodes and with or without addition of Gaussian white noise (GWN). The use of realistic con... Brain Topography journals http://www.medworm.com/rss/comments.php?id=1632807 Wed, 16 Jul 2008 04:00:00 +0100 1632807