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https://www.readbyqxmd.com/read/28645845/the-feature-weighted-receptive-field-an-interpretable-encoding-model-for-complex-feature-spaces
#1
REVIEW
Ghislain St-Yves, Thomas Naselaris
We introduce the feature-weighted receptive field (fwRF), an encoding model designed to balance expressiveness, interpretability and scalability. The fwRFis organized around the notion of a feature map-a transformation of visual stimuli into visual features that preserves the topology of visual space (but not necessarily the native resolution of the stimulus). The key assumption of the fwRFmodel is that activity in each voxel encodes variation in a spatially localized region across multiple feature maps. This region is fixed for all feature maps; however, the contribution of each feature map to voxel activity is weighted...
June 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28645069/controlled-single-bubble-cavitation-collapse-results-in-jet-induced-injury-in-brain-tissue
#2
Saranya Canchi, Karen Kelly, Yu Hong, Michael A King, Ghatu Subhash, Malisa Sarntinoranont
Multiscale damage due to cavitation is considered as a potential mechanism of traumatic brain injury (TBI) associated with explosion. In this study, we employed a TBI relevant hippocampal ex vivo slice model to induce bubble cavitation. Placement of single reproducible seed bubbles allowed control of size, number, and tissue location to visualize and measure deformation parameters. Maximum strain value was measured at 45 µs after bubble collapse, presented with a distinct contour and coincided temporally and spatially with the liquid jet...
June 15, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28641104/constructing-the-external-world
#3
Jiseok Lee, Alison L Barth
In this issue of Neuron, Pluta et al. (2017) find a novel map of external space in primary somatosensory cortex, generated by multi-whisker interactions during active touch.
June 21, 2017: Neuron
https://www.readbyqxmd.com/read/28640923/how-much-detail-is-needed-in-modeling-a-transcranial-magnetic-stimulation-figure-8-coil-measurements-and-brain-simulations
#4
Petar I Petrov, Stefano Mandija, Iris E C Sommer, Cornelis A T van den Berg, Sebastiaan F W Neggers
BACKGROUND: Despite TMS wide adoption, its spatial and temporal patterns of neuronal effects are not well understood. Although progress has been made in predicting induced currents in the brain using realistic finite element models (FEM), there is little consensus on how a magnetic field of a typical TMS coil should be modeled. Empirical validation of such models is limited and subject to several limitations. METHODS: We evaluate and empirically validate models of a figure-of-eight TMS coil that are commonly used in published modeling studies, of increasing complexity: simple circular coil model; coil with in-plane spiral winding turns; and finally one with stacked spiral winding turns...
2017: PloS One
https://www.readbyqxmd.com/read/28640816/topographic-independent-component-analysis-reveals-random-scrambling-of-orientation-in-visual-space
#5
Marina Martinez-Garcia, Luis M Martinez, Jesús Malo
Neurons at primary visual cortex (V1) in humans and other species are edge filters organized in orientation maps. In these maps, neurons with similar orientation preference are clustered together in iso-orientation domains. These maps have two fundamental properties: (1) retinotopy, i.e. correspondence between displacements at the image space and displacements at the cortical surface, and (2) a trade-off between good coverage of the visual field with all orientations and continuity of iso-orientation domains in the cortical space...
2017: PloS One
https://www.readbyqxmd.com/read/28638719/abnormal-amplitude-of-low-frequency-fluctuations-and-functional-connectivity-of-resting-state-functional-magnetic-resonance-imaging-in-patients-with-leukoaraiosis
#6
Rongchuan Cheng, Honglin Qi, Yong Liu, Shifu Zhao, Chuanming Li, Chen Liu, Jian Zheng
INTRODUCTION: This study aimed to investigate the cerebral function deficits in patients with leukoaraiosis (LA) and the correlation with white matter hyperintensity (WMH) using functional MRI (fMRI) technology. MATERIALS AND METHODS: Twenty-eight patients with LA and 30 volunteers were enrolled in this study. All patients underwent structural MRI and resting-state functional MRI (rs-fMRI) scanning. The amplitude of low-frequency fluctuations (ALFF) of rs-fMRI signals for the two groups was compared using two-sample t tests...
June 2017: Brain and Behavior
https://www.readbyqxmd.com/read/28637591/salicylate-induced-frequency-map-reorganization-in-four-subfields-of-the-mouse-auditory-cortex
#7
Yasutaka Yanagawa, Kengo Takasu, Hisayuki Osanai, Takashi Tateno
Salicylate is the active ingredient in aspirin, and in high-doses it is used as an experimental tool to induce transient hearing loss, tinnitus, and hyperacusis. These salicylate-induced perceptual disturbances are associated with tonotopic-map reorganization and neural activity modulation, and such neural correlates have been examined in the central auditory pathway, including the auditory cortex (AC). Although previous studies have reported that salicylate induces increases in noise-burst-evoked neural responses and reorganization of tonotopic maps in the primary AC, little is known about the effects of salicylate on other frequency-organized AC subfields such as the anterior auditory, secondary auditory, and dorsomedial fields...
June 10, 2017: Hearing Research
https://www.readbyqxmd.com/read/28634107/chronic-pramipexole-treatment-induces-compulsive-behavior-in-rats-with-6-ohda-lesions-of-the-substantia-nigra-and-ventral-tegmental-area
#8
D Dardou, L Reyrolle, C Chassain, F Durif
Dopamine replacement therapy (DRT) reduces motor symptoms in Parkinson's disease (PD), but also induces impulsive-compulsive behavior (ICB) in up to 25% of PD patients. These non-motor side effects of DRT generally follow a gradual transition from impulsive to compulsive-like-i.e. repetitive, compelled, and non-pleasurable-behavior. Here, we investigated the effect of chronic pramipexole (PPX) treatment on the onset of compulsive-like behavior, measured via the post-training signal attenuation (PTSA) procedure, in rats with dopaminergic lesions...
June 17, 2017: Behavioural Brain Research
https://www.readbyqxmd.com/read/28631354/cross-population-myelination-covariance-of-human-cerebral-cortex
#9
Zhiwei Ma, Nanyin Zhang
Cross-population covariance of brain morphometric quantities provides a measure of interareal connectivity, as it is believed to be determined by the coordinated neurodevelopment of connected brain regions. Although useful, structural covariance analysis predominantly employed bulky morphological measures with mixed compartments, whereas studies of the structural covariance of any specific subdivisions such as myelin are rare. Characterizing myelination covariance is of interest, as it will reveal connectivity patterns determined by coordinated development of myeloarchitecture between brain regions...
June 20, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28631147/the-motor-cortical-representation-of-a-muscle-is-not-homogeneous-in-brain-connectivity
#10
Jo Armour Smith, Alaa Albishi, Sarine Babikian, Skulpan Asavasopon, Beth E Fisher, Jason J Kutch
Functional connectivity patterns of the motor cortical representational area of single muscles have not been extensively mapped in humans, particularly for the axial musculature. Functional connectivity may provide a neural substrate for adaptation of muscle activity in axial muscles that have both voluntary and postural functions. The purpose of this study was to combine brain stimulation and neuroimaging to both map the cortical representation of the external oblique (EO) in primary motor cortex (M1) and supplementary motor area (SMA), and to establish the resting-state functional connectivity associated with this representation...
June 19, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28630881/review-of-functional-and-clinical-relevance-of-intrinsic-signal-optical-imaging-in-human-brain-mapping
#11
REVIEW
Katherine A Morone, Joseph S Neimat, Anna W Roe, Robert M Friedman
Intrinsic signal optical imaging (ISOI) within the first decade of its use in humans showed its capacity as a precise functional mapping tool. It is a powerful tool that can be used intraoperatively to help a surgeon to directly identify functional areas of the cerebral cortex. Its use is limited to the intraoperative setting as it requires a craniotomy and durotomy for direct visualization of the brain. It has been applied in humans to study language, somatosensory and visual cortices, cortical hemodynamics, epileptiform activity, and lesion delineation...
July 2017: Neurophotonics
https://www.readbyqxmd.com/read/28629975/anatomical-and-functional-properties-of-the-foot-and-leg-representation-in-areas-3b-1-and-2-of-primary-somatosensory-cortex-in-humans-a-7t-fmri-study
#12
Michel Akselrod, Roberto Martuzzi, Andrea Serino, Wietske van der Zwaag, Roger Gassert, Olaf Blanke
Primary somatosensory cortex (S1) processes somatosensory information and is composed of multiple subregions. In particular, tactile information from the skin is encoded in three subregions, namely Brodmann areas (BAs) 3b, 1 and 2, with each area representing a complete map of the contralateral body. Although, much is known about the somatotopic organization of the hand in human S1, less research has been carried out regarding the somatotopic maps of the foot and leg in S1. Moreover, a latero-medial S1 organization along the superior part of the postcentral gyrus has been reported when moving from hip to toes, yet to date there is no study investigating leg/foot maps within the different subregions of S1...
June 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/28629874/neural-activity-during-attentional-conflict-predicts-reduction-in-tinnitus-perception-following-rtms
#13
G A James, J D Thostenson, G Brown, G Carter, H Hayes, S P Tripathi, D J Dobry, R B Govindan, J L Dornhoffer, D K Williams, C D Kilts, M S Mennemeier
BACKGROUND: Subjective idiopathic tinnitus is an intrusive, distracting, and potentially disabling disorder characterized by phantom perception of sounds. Although tinnitus has no approved pharmacologic treatment, recent evidence supports the use of repetitive transcranial magnetic stimulation (rTMS) to alleviate tinnitus symptoms. OBJECTIVE/HYPOTHESIS: Repetitive TMS delivered over the middle superior temporal gyrus (STG) may alter ratings of tinnitus awareness and annoyance more than loudness due to change in attentional processing...
June 2, 2017: Brain Stimulation
https://www.readbyqxmd.com/read/28629720/exploring-connectivity-with-large-scale-granger-causality-on-resting-state-functional-mri
#14
Adora M DSouza, Anas Z Abidin, Lutz Leistritz, Axel Wismüller
BACKGROUND: Large-scale Granger causality (lsGC) is a recently developed, resting-state functional MRI (fMRI) connectivity analysis approach that estimates multivariate voxel-resolution connectivity. Unlike most commonly used multivariate approaches, which establish coarse-resolution connectivity by aggregating voxel time-series avoiding an underdetermined problem, lsGC estimates voxel-resolution, fine-grained connectivity by incorporating an embedded dimension reduction. NEW METHOD: We investigate application of lsGC on realistic fMRI simulations, modeling smoothing of neuronal activity by the hemodynamic response function and repetition time (TR), and empirical resting-state fMRI data...
June 16, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28628004/visual-field-map-clusters-in-human-frontoparietal-cortex
#15
Wayne E Mackey, Jonathan Winawer, Clayton E Curtis
The visual neurosciences have made enormous progress in recent decades, in part because of the ability to drive visual areas by their sensory inputs, allowing researchers to reliably define visual areas across individuals and across species. Similar strategies for parcellating higher-order cortex have proven elusive. Here, using a novel experimental task and nonlinear population receptive field modeling we map and characterize the topographic organization of several regions in human frontoparietal cortex. We discover representations of both polar angle and eccentricity that are organized into clusters, similar to visual cortex, where multiple gradients of polar angle of the contralateral visual field share a confluent fovea...
June 19, 2017: ELife
https://www.readbyqxmd.com/read/28627420/distinct-neural-processes-support-post-success-and-post-error-slowing-in-the-stop-signal-task
#16
Yihe Zhang, Jaime S Ide, Sheng Zhang, Sien Hu, Nikola S Valchev, Xiaoying Tang, Chiang-Shan R Li
Executive control requires behavioral adaptation to environmental contingencies. In the stop signal task (SST), participants exhibit slower go trial reaction time (RT) following a stop trial, whether or not they successfully interrupt the motor response. In previous fMRI studies, we demonstrated activation of the right-hemispheric ventrolateral prefrontal cortex, in the area of inferior frontal gyrus, pars opercularis (IFGpo) and anterior insula (AI), during post-error slowing (PES). However, in similar analyses we were not able to identify regional activities during post-success slowing (PSS)...
June 13, 2017: Neuroscience
https://www.readbyqxmd.com/read/28626411/dissociated-crossed-speech-areas-in-a-tumour-patient
#17
Jörg Mauler, Irene Neuner, Georg Neuloh, Bruno Fimm, Frank Boers, Martin Wiesmann, Hans Clusmann, Karl-Josef Langen, N Jon Shah
In the past, the eloquent areas could be deliberately localised by the invasive Wada test. The very rare cases of dissociated crossed speech areas were accidentally found based on the clinical symptomatology. Today functional magnetic resonance imaging (fMRI)-based imaging can be employed to non-invasively localise the eloquent areas in brain tumour patients for therapy planning. A 41-year-old, left-handed man with a low-grade glioma in the left frontal operculum extending to the insular cortex, tension headaches, and anomic aphasia over 5 months underwent a pre-operative speech area localisation fMRI measurement, which revealed the evidence of the transhemispheric disposition, where the dominant Wernicke speech area is located on the left and the Broca's area is strongly lateralised to the right hemisphere...
May 2017: Case Reports in Neurology
https://www.readbyqxmd.com/read/28626050/admission-brain-cortical-volume-an-independent-determinant-of-poststroke-cognitive-vulnerability
#18
Sharmila Sagnier, Gwenaëlle Catheline, Bixente Dilharreguy, Fanny Munsch, Antoine Bigourdan, Mathilde Poli, Sabrina Debruxelles, Stéphane Olindo, Pauline Renou, François Rouanet, Vincent Dousset, Thomas Tourdias, Igor Sibon
BACKGROUND AND PURPOSE: Several markers of poststroke cognitive impairment have been reported. The role of brain cortical volume remains uncertain. The aim of this study was to evaluate the influence of brain cortical volume on cognitive outcomes using a voxel-based morphometry approach in subjects without prestroke dementia. METHODS: Ischemic stroke patients were prospectively recruited 24 to 72 hours post-stroke (M0). Cognition was evaluated at M0, 3 months, and 1 year (M12) using the Montreal Cognitive Assessment, the Isaacs set test, and the Zazzo's cancellation task...
June 16, 2017: Stroke; a Journal of Cerebral Circulation
https://www.readbyqxmd.com/read/28625485/motor-cortical-visuomotor-feedback-activity-is-initially-isolated-from-downstream-targets-in-output-null-neural-state-space-dimensions
#19
Sergey D Stavisky, Jonathan C Kao, Stephen I Ryu, Krishna V Shenoy
Neural circuits must transform new inputs into outputs without prematurely affecting downstream circuits while still maintaining other ongoing communication with these targets. We investigated how this isolation is achieved in the motor cortex when macaques received visual feedback signaling a movement perturbation. To overcome limitations in estimating the mapping from cortex to arm movements, we also conducted brain-machine interface (BMI) experiments where we could definitively identify neural firing patterns as output-null or output-potent...
June 6, 2017: Neuron
https://www.readbyqxmd.com/read/28623837/abnormal-asymmetry-in-benign-epilepsy-with-unilateral-and-bilateral-centrotemporal-spikes-a-combined-fmri-and-dti-study
#20
Weifang Cao, Yaodan Zhang, Changyue Hou, Fei Yang, Jinnan Gong, Sisi Jiang, Yue Huang, Ruhui Xiao, Cheng Luo, Xiaoming Wang, Dezhong Yao
Benign epilepsy with centrotemporal spikes (BECTS) is the most common idiopathic focal childhood epilepsy associated with either unilateral or bilateral epileptic discharge. Asymmetry as an important characteristic of the human brain is beneficial for brain functions. However, little is known about on asymmetry of BECTS patients with different epileptic spikes pattern. In the present study, we investigated functional and structural asymmetries in unilateral spikes BECTS (U_BECTS) patients and bilateral spikes BECTS (B_BECTS) patients using resting state functional magnetic resonance images and diffusion tensor imaging...
June 8, 2017: Epilepsy Research
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