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https://www.readbyqxmd.com/read/29219756/awake-perimetry-testing-for-occipital-epilepsy-surgery
#1
Holger Joswig, John P Girvin, Warren T Blume, Jorge G Burneo, David A Steven
In the literature, there are few reports that provide a detailed account on the technique of visual electrocortical stimulation in the setting of resective surgery for occipital epilepsy. In this technical note, the authors describe how a 26-year-old male with long-standing occipital epilepsy underwent resective surgery under awake conditions, using electrocortical stimulation of the occipital lobe, with the aid of a laser pointer and a perimetry chart on a stand within his visual field. The eloquent primary visual cortex was found to overlap with the seizure onset zone that was previously determined with subdural electrodes...
December 8, 2017: Journal of Neurosurgery
https://www.readbyqxmd.com/read/29214728/disruption-of-network-for-visual-perception-of-natural-motion-in-primary-dystonia
#2
Koji Fujita, Wataru Sako, An Vo, Susan B Bressman, David Eidelberg
In healthy subjects, brain activation in motor regions is greater during the visual perception of "natural" target motion, which complies with the two-thirds power law, than of "unnatural" motion, which does not. It is unknown whether motion perception is normally mediated by a specific network that can be altered in the setting of disease. We used block-design functional magnetic resonance imaging and covariance analysis to identify normal network topographies activated in response to "natural" versus "unnatural" motion...
December 6, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/29203280/reduced-post-stroke-glial-scarring-in-the-infant-primate-brain-reflects-age-related-differences-in-the-regulation-of-astrogliosis
#3
Leon Teo, Anthony G Boghdadi, Mitchell de Souza, James A Bourne
Ischemic stroke remains a leading cause of disability worldwide. Surviving patients often suffer permanent neurological impairments, and spontaneous recovery rarely occurs. However, observations that early-life brain injuries, including strokes, elicit less severe long-term functional impairments, compared to adults, continue to intrigue. While much research has focussed on neuronal changes and plasticity, less is known regarding the regulation of astrogliosis and glial scar formation after a stroke at different stages of life...
December 1, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/29201639/visual-feedback-alters-force-control-and-functional-activity-in-the-visuomotor-network-after-stroke
#4
Derek B Archer, Nyeonju Kang, Gaurav Misra, Shannon Marble, Carolynn Patten, Stephen A Coombes
Modulating visual feedback may be a viable option to improve motor function after stroke, but the neurophysiological basis for this improvement is not clear. Visual gain can be manipulated by increasing or decreasing the spatial amplitude of an error signal. Here, we combined a unilateral visually guided grip force task with functional MRI to understand how changes in the gain of visual feedback alter brain activity in the chronic phase after stroke. Analyses focused on brain activation when force was produced by the most impaired hand of the stroke group as compared to the non-dominant hand of the control group...
2018: NeuroImage: Clinical
https://www.readbyqxmd.com/read/29196811/cortical-and-subcortical-connections-of-parietal-and-premotor-nodes-of-the-monkey-hand-mirror-neuron-network
#5
Stefania Bruni, Marzio Gerbella, Luca Bonini, Elena Borra, Gino Coudé, Pier Francesco Ferrari, Leonardo Fogassi, Monica Maranesi, Francesca Rodà, Luciano Simone, Francesca Ugolotti Serventi, Stefano Rozzi
Mirror neurons (MNs) are a class of cells originally discovered in the monkey ventral premotor cortex (PMv) and inferior parietal lobule (IPL). They discharge during both action execution and action observation and appear to play a crucial role in understanding others' actions. It has been proposed that the mirror mechanism is based on a match between the visual description of actions, encoded in temporal cortical regions, and their motor representation, provided by PMv and IPL. However, neurons responding to action observation have been recently found in other cortical regions, suggesting that the mirror mechanism relies on a wider network...
December 1, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/29196320/inhibition-in-simple-cell-receptive-fields-is-broad-and-off-subregion-biased
#6
M Morgan Taylor, Madineh Sedigh-Sarvestani, Leif Vigeland, Larry A Palmer, Diego Contreras
Inhibition in thalamorecipient layer 4 simple cells of primary visual cortex is believed to play important roles in establishing visual response properties and integrating visual inputs across their receptive fields (RFs). Simple cell RFs are characterized by non-overlapping, spatially restricted subregions in which visual stimuli can either increase or decrease the cell's firing rate, depending on contrast. Inhibition is believed to be triggered exclusively from visual stimulation of individual RF subregions...
December 1, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29190741/preoperative-transcranial-direct-current-stimulation-exploration-of-a-novel-strategy-to-enhance-neuroplasticity-before-surgery-to-control-postoperative-pain-a-randomized-sham-controlled-study
#7
Hugo Ribeiro, Ricardo Bertol Sesterhenn, Andressa de Souza, Ana Claudia de Souza, Monique Alves, Jessica Catarina Machado, Nathalia Bofill Burger, Iraci Lucena da Silva Torres, Luciana Cadore Stefani, Felipe Fregni, Wolnei Caumo
BACKGROUND: An imbalance in the excitatory/inhibitory systems in the pain networks may explain the persistent chronic pain after hallux valgus surgery. Thus, to contra-regulate this dysfunction, the use of transcranial direct current stimulation (tDCS) becomes attractive. OBJECTIVE: We tested the hypothesis that two preoperative active(a)-tDCS sessions compared with sham(s)-tDCS could improve the postoperative pain [as indexed by Visual Analogue Scale (VAS) at rest and during walking (primary outcomes)]...
2017: PloS One
https://www.readbyqxmd.com/read/29190326/major-feedforward-thalamic-input-into-layer-4c-of-primary-visual-cortex-in-primate
#8
Virginia Garcia-Marin, Jenna G Kelly, Michael J Hawken
One of the underlying principles of how mammalian circuits are constructed is the relative influence of feedforward to recurrent synaptic drive. It has been dogma in sensory systems that the thalamic feedforward input is relatively weak and that there is a large amplification of the input signal by recurrent feedback. Here we show that in trichromatic primates there is a major feedforward input to layer 4C of primary visual cortex. Using a combination of 3D-electron-microscopy and 3D-confocal imaging of thalamic boutons we found that the average feedforward contribution was about 20% of the total excitatory input in the parvocellular (P) pathway, about 3 times the currently accepted values for primates...
November 28, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/29186348/spiking-suppression-precedes-cued-attentional-enhancement-of-neural-responses-in-primary-visual-cortex
#9
Michele A Cox, Kacie Dougherty, Geoffrey K Adams, Eric A Reavis, Jacob A Westerberg, Brandon S Moore, David A Leopold, Alexander Maier
Attending to a visual stimulus increases its detectability, even if gaze is directed elsewhere. This covert attentional selection is known to enhance spiking across many brain areas, including the primary visual cortex (V1). Here we investigate the temporal dynamics of attention-related spiking changes in V1 of macaques performing a task that separates attentional selection from the onset of visual stimulation. We found that preceding attentional enhancement there was a sharp, transient decline in spiking following presentation of an attention-guiding cue...
November 23, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/29184207/lateral-geniculate-neurons-projecting-to-primary-visual-cortex-show-ocular-dominance-plasticity-in-adult-mice
#10
Juliane Jaepel, Mark Hübener, Tobias Bonhoeffer, Tobias Rose
Experience-dependent plasticity in the mature visual system is widely considered to be cortical. Using chronic two-photon Ca2+ imaging of thalamic afferents in layer 1 of binocular visual cortex, we provide evidence against this tenet: the respective dorsal lateral geniculate nucleus (dLGN) cells showed pronounced ocular dominance (OD) shifts after monocular deprivation in adult mice. Most (86%), but not all, of dLGN cell boutons were monocular during normal visual experience. Following deprivation, initially deprived-eye-dominated boutons reduced or lost their visual responsiveness to that eye and frequently became responsive to the non-deprived eye...
December 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/29184199/thalamic-inhibition-regulates-critical-period-plasticity-in-visual-cortex-and-thalamus
#11
Jean-Pierre Sommeijer, Mehran Ahmadlou, M Hadi Saiepour, Koen Seignette, Rogier Min, J Alexander Heimel, Christiaan N Levelt
During critical periods of development, experience shapes cortical circuits, resulting in the acquisition of functions used throughout life. The classic example of critical-period plasticity is ocular dominance (OD) plasticity, which optimizes binocular vision but can reduce the responsiveness of the primary visual cortex (V1) to an eye providing low-grade visual input. The onset of the critical period of OD plasticity involves the maturation of inhibitory synapses within V1, specifically those containing the GABAA receptor α1 subunit...
December 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/29182610/bdnf-expression-in-cat-striate-cortex-is-regulated-by-binocular-pattern-deprivation
#12
Karolina Laskowska-Macios, Lutgarde Arckens, Małgorzata Kossut, Kalina Burnat
Deprivation of patterned visual information, as in early onset congenital cataract patients, results in a severe impairment in global motion perception. Previously we reported a delayed maturation of the peripheral visual field representation in primary visual area 17, based on a 2-D DIGE screen for protein expression changes and in situ hybridization for the activity reporter gene ZIF268. To corroborate these findings we here explore the binocular pattern deprivation (BD)-regulated expression of brain-derived neurotrophic factor (BDNF), a well-described neurotrophin precipitously regulated by early visual experience...
2017: Acta Neurobiologiae Experimentalis
https://www.readbyqxmd.com/read/29181831/molecular-guidance-cues-in-the-development-of-visual-pathway
#13
REVIEW
Yupu Diao, Yuqing Chen, Peijun Zhang, Liyuan Cui, Jiayi Zhang
70%-80% of our sensory input comes from vision. Light hit the retina at the back of our eyes and the visual information is relayed into the dorsal lateral geniculate nuclei (dLGN) and primary visual cortex (V1) thereafter, constituting the image-forming visual circuit. Molecular cues are one of the key factors to guide the wiring and refinement of the image-forming visual circuit during pre- and post-embryonic stages. Distinct molecular cues are involved in different developmental stages and nucleus, suggesting diverse guidance mechanisms...
November 27, 2017: Protein & Cell
https://www.readbyqxmd.com/read/29179629/spinal-cord-injury-disrupts-resting-state-networks-in-the-human-brain
#14
Ammar Hawasli, Jerrel Rutlin, Jarod L Roland, Rory Murphy, Sheng-Kwei Song, Eric Leuthardt, Joshua Shimony, Wilson Z Ray
Despite 253,000 spinal cord injury (SCI) patients in America, little is known about how SCI affects brain networks. Spinal magnetic resonance imaging (MRI) provides only structural information with no insight into functional connectivity. Resting-state functional MRI (RS-fMRI) quantifies network connectivity through the identification of resting-state networks (RSNs) and allows detection of functionally-relevant changes during disease. Given the robust network of spinal cord afferents to the brain, we hypothesized SCI produces meaningful changes in brain RSNs...
November 27, 2017: Journal of Neurotrauma
https://www.readbyqxmd.com/read/29178660/motion-contrast-in-primary-visual-cortex-a-direct-comparison-of-single-neuron-and-population-encoding
#15
Sergio A Conde-Ocazionez, Tiago S Altavini, Thomas Wunderle, Kerstin E Schmidt
Features from outside the classical receptive field (CRF) can modulate the stimulus-driven activity of single cells in the primary visual cortex. This modulation, mediated by horizontal and feedback networks, has been extensively described as a variation of firing rate and is considered the basis of processing features as, for example, motion contrast. However, surround influences have also been identified in pairwise spiking or local field coherence. Yet, evidence about co-existence and integration of different neural signatures remains elusive...
November 27, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/29176725/distinct-neural-substrates-of-visuospatial-and-verbal-analytic-reasoning-as-assessed-by-raven-s-advanced-progressive-matrices
#16
Zhencai Chen, Alain De Beuckelaer, Xu Wang, Jia Liu
Recent studies revealed spontaneous neural activity to be associated with fluid intelligence (gF) which is commonly assessed by Raven's Advanced Progressive Matrices, and embeds two types of reasoning: visuospatial and verbal-analytic reasoning. With resting-state fMRI data, using global brain connectivity (GBC) analysis which averages functional connectivity of a voxel in relation to all other voxels in the brain, distinct neural correlates of these two reasoning types were found. For visuospatial reasoning, negative correlations were observed in both the primary visual cortex (PVC) and the precuneus, and positive correlations were observed in the temporal lobe...
November 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29168583/distinct-patterns-of-amyloid-dependent-tau-accumulation-in-lewy-body-diseases
#17
Seung Ha Lee, Hanna Cho, Jae Yong Choi, Jae Hoon Lee, Young Hoon Ryu, Myung Sik Lee, Chul Hyoung Lyoo
BACKGROUND: In addition to Lewy body pathology, amyloid-β plaques and neurofibrillary tangles that are characteristic for Alzheimer's disease are also frequently found in Lewy body diseases. OBJECTIVES: The objective of this study was to investigate tau accumulation patterns in dementia with Lewy bodies and other Lewy body diseases using in vivo (18) F-AV-1451 PET. METHODS: The study included 12 Parkinson's disease (PD) patients with normal cognition, 22 PD patients with cognitive impairment, and 18 dementia with Lewy bodies patients...
November 23, 2017: Movement Disorders: Official Journal of the Movement Disorder Society
https://www.readbyqxmd.com/read/29167810/the-pre-parasubiculum-a-hippocampal-hub-for-scene-based-cognition
#18
REVIEW
Marshall A Dalton, Eleanor A Maguire
Internal representations of the world in the form of spatially coherent scenes have been linked with cognitive functions including episodic memory, navigation and imagining the future. In human neuroimaging studies, a specific hippocampal subregion, the pre/parasubiculum, is consistently engaged during scene-based cognition. Here we review recent evidence to consider why this might be the case. We note that the pre/parasubiculum is a primary target of the parieto-medial temporal processing pathway, it receives integrated information from foveal and peripheral visual inputs and it is contiguous with the retrosplenial cortex...
October 2017: Current Opinion in Behavioral Sciences
https://www.readbyqxmd.com/read/29163117/deep-learning-predicts-correlation-between-a-functional-signature-of-higher-visual-areas-and-sparse-firing-of-neurons
#19
Chengxu Zhuang, Yulong Wang, Daniel Yamins, Xiaolin Hu
Visual information in the visual cortex is processed in a hierarchical manner. Recent studies show that higher visual areas, such as V2, V3, and V4, respond more vigorously to images with naturalistic higher-order statistics than to images lacking them. This property is a functional signature of higher areas, as it is much weaker or even absent in the primary visual cortex (V1). However, the mechanism underlying this signature remains elusive. We studied this problem using computational models. In several typical hierarchical visual models including the AlexNet, VggNet, and SHMAX, this signature was found to be prominent in higher layers but much weaker in lower layers...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/29159914/gaba-concentration-in-sensorimotor-cortex-following-high-intensity-exercise-and-relationship-to-lactate-levels
#20
James P Coxon, Robin F H Cash, Joshua J Hendrikse, Nigel C Rogasch, Ellen Stavrinos, Chao Suo, Murat Yücel
High-intensity exercise increases the concentration of circulating lactate. Cortical uptake of blood borne lactate increases during and following exercise, however the potential relationship with changes in the concentration of neurometabolites remains unclear. While changes in neurometabolite concentration have previously been demonstrated in primary visual cortex following exercise, it remains unknown whether these changes extend to regions such as sensorimotor cortex (SM) or executive regions such as dorsolateral prefrontal cortex (DLPFC)...
November 21, 2017: Journal of Physiology
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