keyword
MENU ▼
Read by QxMD icon Read
search

Primary visual cortex

keyword
https://www.readbyqxmd.com/read/28545983/feedback-from-higher-to-lower-visual-areas-for-visual-recognition-may-be-weaker-in-the-periphery-glimpses-from-the-perception-of-brief-dichoptic-stimuli
#1
Li Zhaoping
Eye movements bring attended visual inputs to the center of vision for further processing. Thus, central and peripheral vision should have different functional roles. Here, we use observations of visual perception under dichoptic stimuli to infer that there is a difference in the top-down feedback from higher brain centers to primary visual cortex. Visual stimuli to the two eyes were designed such that the sum and difference of the binocular input from the two eyes have the form of two different gratings. These gratings differed in their motion direction, tilt direction, or color, and duly evoked ambiguous percepts for the corresponding feature...
May 22, 2017: Vision Research
https://www.readbyqxmd.com/read/28542191/spontaneous-cortical-activity-is-transiently-poised-close-to-criticality
#2
Gerald Hahn, Adrian Ponce-Alvarez, Cyril Monier, Giacomo Benvenuti, Arvind Kumar, Frédéric Chavane, Gustavo Deco, Yves Frégnac
Brain activity displays a large repertoire of dynamics across the sleep-wake cycle and even during anesthesia. It was suggested that criticality could serve as a unifying principle underlying the diversity of dynamics. This view has been supported by the observation of spontaneous bursts of cortical activity with scale-invariant sizes and durations, known as neuronal avalanches, in recordings of mesoscopic cortical signals. However, the existence of neuronal avalanches in spiking activity has been equivocal with studies reporting both its presence and absence...
May 24, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28539425/perceptual-competition-promotes-suppression-of-reward-salience-in-behavioral-selection-and-neural-representation
#3
Mengyuan Gong, Ke Jia, Sheng Li
Visual attentional selection is influenced by the value of objects. Previous studies have demonstrated that reward-associated items lead to rapid distraction and associated behavioral costs, which are difficult to override with top-down control. However, it has not been determined whether a perceptually competitive environment could render the reward-driven distraction more susceptible to top-down suppression. Here, we trained both genders of human subjects to associate two orientations with high and low magnitudes of reward...
May 24, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28534870/time-compressed-preplay-of-anticipated-events-in-human-primary-visual-cortex
#4
Matthias Ekman, Peter Kok, Floris P de Lange
Perception is guided by the anticipation of future events. It has been hypothesized that this process may be implemented by pattern completion in early visual cortex, in which a stimulus sequence is recreated after only a subset of the visual input is provided. Here we test this hypothesis using ultra-fast functional magnetic resonance imaging to measure BOLD activity at precisely defined receptive field locations in visual cortex (V1) of human volunteers. We find that after familiarizing subjects with a spatial sequence, flashing only the starting point of the sequence triggers an activity wave in V1 that resembles the full stimulus sequence...
May 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28534668/does-spatial-attention-modulate-the-earliest-component-of-the-visual-evoked-potential
#5
Hannah M Baumgartner, Christian J Graulty, Steven A Hillyard, Michael A Pitts
Whether visual spatial attention can modulate feedforward input to human primary visual cortex (V1) is debated. A prominent and long-standing hypothesis is that visual spatial attention can influence processing in V1, but only at delayed latencies suggesting a feedback-mediated mechanism and a lack of modulation during the initial afferent volley. The most promising challenge to this hypothesis comes from an event-related potential (ERP) study that showed an amplitude enhancement of the earliest visual ERP component, called the "C1", in response to spatially-attended relative to spatially-unattended stimuli (Kelly et al...
May 23, 2017: Cognitive Neuroscience
https://www.readbyqxmd.com/read/28533402/behavioral-and-neural-correlates-to-multisensory-detection-of-sick-humans
#6
Christina Regenbogen, John Axelsson, Julie Lasselin, Danja K Porada, Tina Sundelin, Moa G Peter, Mats Lekander, Johan N Lundström, Mats J Olsson
Throughout human evolution, infectious diseases have been a primary cause of death. Detection of subtle cues indicating sickness and avoidance of sick conspecifics would therefore be an adaptive way of coping with an environment fraught with pathogens. This study determines how humans perceive and integrate early cues of sickness in conspecifics sampled just hours after the induction of immune system activation, and the underlying neural mechanisms for this detection. In a double-blind placebo-controlled crossover design, the immune system in 22 sample donors was transiently activated with an endotoxin injection [lipopolysaccharide (LPS)]...
May 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28533117/activation-induced-changes-in-gaba-functional-mrs-at-7t-with-mega-slaser
#7
Chen Chen, Hilmar P Sigurdsson, Sophia E Pépés, Dorothee P Auer, Peter G Morris, Paul S Morgan, Penny A Gowland, Stephen R Jackson
Functional magnetic resonance spectroscopy (fMRS) has been used to assess the dynamic metabolic responses of the brain to a physiological stimulus non-invasively. However, only limited information on the dynamic functional response of γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain, is available. We aimed to measure the activation-induced changes in GABA unambiguously using a spectral editing method, instead of the conventional direct detection techniques used in previous fMRS studies...
May 19, 2017: NeuroImage
https://www.readbyqxmd.com/read/28532362/mechanisms-of-orientation-selectivity-in-the-primary-visual-cortex
#8
Nicholas J Priebe
The mechanisms underlying the emergence of orientation selectivity in the visual cortex have been, and continue to be, the subjects of intense scrutiny. Orientation selectivity reflects a dramatic change in the representation of the visual world: Whereas afferent thalamic neurons are generally orientation insensitive, neurons in the primary visual cortex (V1) are extremely sensitive to stimulus orientation. This profound change in the receptive field structure along the visual pathway has positioned V1 as a model system for studying the circuitry that underlies neural computations across the neocortex...
October 14, 2016: Annual Review of Vision Science
https://www.readbyqxmd.com/read/28532356/probing-human-visual-deficits-with-functional-magnetic-resonance-imaging
#9
Stelios M Smirnakis
Much remains to be understood about visual system malfunction following injury. The resulting deficits range from dense, visual field scotomas to mild dysfunction of visual perception. Despite the predictive value of anatomical localization studies, much patient-to-patient variability remains regarding (a) perceptual abilities following injury and (b) the capacity of individual patients for visual rehabilitation. Visual field perimetry is used to characterize the visual field deficits that result from visual system injury...
October 14, 2016: Annual Review of Vision Science
https://www.readbyqxmd.com/read/28531897/magnetic-resonance-imaging-of-the-brain-of-a-monotreme-the-short-beaked-echidna-tachyglossus-aculeatus
#10
Sandilya Cherupalli, Craig D Hardman, Andre Bongers, Ken W S Ashwell
We used magnetic resonance imaging to study the anatomy of cortical regions, nuclear groups, and major tracts in the brain of a monotreme, i.e., the short-beaked echidna (Tachyglossus aculeatus). Our specimens were from a collection held at the Australian Museum in Sydney and had been stored in formaldehyde solution for at least 70 years. Despite this, we were able to detect fine detail in the nuclear divisions of structures as well as in fiber tracts. In particular, we could detect the medial lemniscus as it approached the ventral posterior thalamic nucleus, subdivisions within the ventral posterior thalamic nucleus, lamination and subdivisions within the hippocampal formation, components of the olfactory pathways, and nuclei within the temporal amygdala...
May 23, 2017: Brain, Behavior and Evolution
https://www.readbyqxmd.com/read/28530661/causal-evidence-for-retina-dependent-and-independent-visual-motion-computations-in-mouse-cortex
#11
Daniel Hillier, Michele Fiscella, Antonia Drinnenberg, Stuart Trenholm, Santiago B Rompani, Zoltan Raics, Gergely Katona, Josephine Juettner, Andreas Hierlemann, Balazs Rozsa, Botond Roska
How neuronal computations in the sensory periphery contribute to computations in the cortex is not well understood. We examined this question in the context of visual-motion processing in the retina and primary visual cortex (V1) of mice. We disrupted retinal direction selectivity, either exclusively along the horizontal axis using FRMD7 mutants or along all directions by ablating starburst amacrine cells, and monitored neuronal activity in layer 2/3 of V1 during stimulation with visual motion. In control mice, we found an over-representation of cortical cells preferring posterior visual motion, the dominant motion direction an animal experiences when it moves forward...
May 22, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28523280/differences-in-orientation-tuning-between-pinwheel-and-domain-neurons-in-primary-visual-cortex-depend-on-contrast-and-size
#12
Yong-Jun Liu, Maziar Hashemi-Nezhad, David C Lyon
Intrinsic signal optical imaging reveals a highly modular map of orientation preference in the primary visual cortex (V1) of several species. This orientation map is characterized by domains and pinwheels where local circuitry is either more or less orientation selective, respectively. It has now been repeatedly demonstrated that neurons in pinwheels tend to be more broadly tuned to orientation, likely due to the broad range of orientation preference of the neighboring neurons forming pinwheels. However, certain stimulus conditions, such as a decrease in contrast or an increase in size, significantly sharpen tuning widths of V1 neurons...
July 2017: Neurophotonics
https://www.readbyqxmd.com/read/28520739/timing-dependent-ltp-and-ltd-in-mouse-primary-visual-cortex-following-different-visual-deprivation-models
#13
Yatu Guo, Wei Zhang, Xia Chen, Junhong Fu, Wenbo Cheng, Desheng Song, Xiaolei Qu, Zhuo Yang, Kanxing Zhao
Visual deprivation during the critical period induces long-lasting changes in cortical circuitry by adaptively modifying neuro-transmission and synaptic connectivity at synapses. Spike timing-dependent plasticity (STDP) is considered a strong candidate for experience-dependent changes. However, the visual deprivation forms that affect timing-dependent long-term potentiation(LTP) and long-term depression(LTD) remain unclear. Here, we demonstrated the temporal window changes of tLTP and tLTD, elicited by coincidental pre- and post-synaptic firing, following different modes of 6-day visual deprivation...
2017: PloS One
https://www.readbyqxmd.com/read/28512442/posterior-anterior-brain-maturation-reflected-in-perceptual-motor-and-cognitive-performance
#14
Patrícia Gerván, Péter Soltész, Orsolya Filep, Andrea Berencsi, Ilona Kovács
Based on several postmortem morphometric and in vivo imaging studies it has been postulated that brain maturation roughly follows a caudal to rostral direction. In this study, we linked this maturational pattern to psychological function employing a series of well-established behavioral tasks. We addressed three distinct functions and brain regions with a perceptual (contour integration, CI), motor (finger tapping, FT), and executive control (Navon global-local) task. Our purpose was to investigate basic visual integration functions relying on primary visual cortex (V1) in CI; motor coordination function related to primary motor cortex (M1) in FT, and the executive control component, switching, related to the dorsolateral prefrontal region of the brain in the Navon task...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28508035/flashing-lights-induce-prolonged-distortions-in-visual-cortical-responses-and-visual-perception
#15
Genki Minamisawa, Kenta Funayama, Nobuyoshi Matsumoto, Norio Matsuki, Yuji Ikegaya
The primary sensory neocortex generates an internal representation of the environment, and its circuit reorganization is thought to lead to a modification of sensory perception. This reorganization occurs primarily through activity-dependent plasticity and has been well documented in animals during early developmental stages. Here, we describe a new method for the noninvasive induction of long-term plasticity in the mature brain: simple transient visual stimuli (i.e., flashing lights) can be used to induce prolonged modifications in visual cortical processing and visually driven behaviors...
May 2017: ENeuro
https://www.readbyqxmd.com/read/28507133/cholinergic-shaping-of-neural-correlations
#16
Victor Minces, Lucas Pinto, Yang Dan, Andrea A Chiba
A primary function of the brain is to form representations of the sensory world. Its capacity to do so depends on the relationship between signal correlations, associated with neuronal receptive fields, and noise correlations, associated with neuronal response variability. It was recently shown that the behavioral relevance of sensory stimuli can modify the relationship between signal and noise correlations, presumably increasing the encoding capacity of the brain. In this work, we use data from the visual cortex of the awake mouse watching naturalistic stimuli and show that a similar modification is observed under heightened cholinergic modulation...
May 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28507127/development-of-visual-category-selectivity-in-ventral-visual-cortex-does-not-require-visual-experience
#17
Job van den Hurk, Marc Van Baelen, Hans P Op de Beeck
To what extent does functional brain organization rely on sensory input? Here, we show that for the penultimate visual-processing region, ventral-temporal cortex (VTC), visual experience is not the origin of its fundamental organizational property, category selectivity. In the fMRI study reported here, we presented 14 congenitally blind participants with face-, body-, scene-, and object-related natural sounds and presented 20 healthy controls with both auditory and visual stimuli from these categories. Using macroanatomical alignment, response mapping, and surface-based multivoxel pattern analysis, we demonstrated that VTC in blind individuals shows robust discriminatory responses elicited by the four categories and that these patterns of activity in blind subjects could successfully predict the visual categories in sighted controls...
May 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28506486/preoperative-and-intraoperative-neurophysiological-investigations-for-surgical-resections-in-functional-areas
#18
G Huberfeld, A Trébuchon, L Capelle, J-M Badier, S Chen, J-P Lefaucheur, M Gavaret
Brain regions are removed to treat lesions, but great care must be taken not to disturb or remove functional areas in the lesion and in surrounding tissue where healthy and diseased cells may be intermingled, especially for infiltrating tumors. Cortical functional areas and fiber tracts can be localized preoperatively by probabilistic anatomical tools, but mapping of functional integrity by neurophysiology is essential. Identification of the primary motor cortex seems to be more effectively performed with transcranial magnetic stimulation (TMS) than functional magnetic resonance imaging (fMRI)...
May 12, 2017: Neuro-Chirurgie
https://www.readbyqxmd.com/read/28503804/neural-correlates-of-visuomotor-adjustments-during-scaling-of-human-finger-movements-fmri-during-visuomotor-scaling-of-finger-movements
#19
Johannes Brand, Lars Michels, Romy Bakker, Marie-Claude Hepp-Reymond, Daniel Kiper, Manfred Morari, Kynan Eng
Visually guided finger movements include online feedback of current effector position to guide target approach. This visual feedback may be scaled or otherwise distorted by unpredictable perturbations. Although adjustments to visual feedback scaling have been studied before, the underlying brain activation differences between upscaling (visual feedback larger than real movement) and downscaling (feedback smaller than real movement) are currently unknown. Brain activation differences between upscaling and downscaling might be expected because within-trial adjustments during upscaling require corrective backwards accelerations, whereas correcting for downscaling requires forward accelerations...
May 15, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28500299/visual-processing-mode-switching-regulated-by-vip-cells
#20
Jung Hoon Lee, Stefan Mihalas
The responses of neurons in mouse primary visual cortex (V1) to visual stimuli depend on behavioral states. Specifically, surround suppression is reduced during locomotion. Although locomotion-induced vasoactive intestinal polypeptide positive (VIP) interneuron depolarization can account for the reduction of surround suppression, the functions of VIP cell depolarization are not fully understood. Here we utilize a firing rate model and a computational model to elucidate the potential functions of VIP cell depolarization during locomotion...
May 12, 2017: Scientific Reports
keyword
keyword
54569
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"