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Primary visual cortex

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https://www.readbyqxmd.com/read/28822837/delayed-pain-decrease-following-m1-tdcs-in-spinal-cord-injury-a-randomized-controlled-clinical-trial
#1
Aurore Thibaut, Sandra Carvalho, Leslie Morse, Ross Zafonte, Felipe Fregni
Despite some encouraging findings for the treatment of neuropathic pain in patients with spinal cord injury (SCI), transcranial direct current stimulation (tDCS) directed to the primary motor cortex (M1) has faced some mixed results. Prior to translating this technology to clinical care, consistent results and durable effects need to be found. We, therefore, aimed to assess the direct and long-term effects of tDCS on pain following SCI. We performed a two-phase randomized sham-controlled clinical trial where patients received 5days of tDCS followed by at 3-month follow-up period (Phase I); then, Phase II consisted of 10days of tDCS with an 8-week follow-up period...
August 16, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28821808/repetition-suppression-to-objects-is-modulated-by-stimulus-specific-expectations
#2
Christian Utzerath, Elexa St John-Saaltink, Jan Buitelaar, Floris P de Lange
Repeated exposure to the same stimulus results in an attenuated brain response in cortical regions that are activated during the processing of that stimulus. This phenomenon, called repetition suppression (RS), has been shown to be modulated by expectation. Typically, this is achieved by varying the probability of stimulus repetitions (Prep) between blocks of an experiment, generating an abstract expectation that 'things will repeat'. Here, we examined whether stimulus-specific expectations also modulate RS...
August 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28821672/audio-visual-modulation-in-mouse-v1-depends-on-cross-modal-stimulus-configuration-and-congruency
#3
Guido T Meijer, Jorrit S Montijn, Cyriel M A Pennartz, Carien S Lansink
The sensory neocortex is a highly connected associative network, in which information from multiple senses is integrated, even at the level of the primary sensory areas. Although this view is supported by a growing body of empirical evidence, the neural mechanisms of cross-modal integration in primary sensory areas, such as the primary visual cortex (V1), are still largely unknown. Using two-photon calcium imaging in awake mice, we show that the encoding of audio-visual stimuli in V1 neuronal populations is highly dependent on the features of the stimulus constituents...
August 8, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28821662/visual-receptive-field-heterogeneity-and-functional-connectivity-of-adjacent-neurons-in-primate-fronto-parietal-association-cortices
#4
Pooja Viswanathan, Andreas Nieder
The basic organization principles of the primary visual cortex (V1) are commonly assumed to also hold in the association cortex such that neurons within a cortical column share functional connectivity patterns and represent the same region of the visual field. We mapped the visual receptive fields (RFs) of neurons recorded at the same electrode in the ventral intraparietal area (VIP) and the lateral prefrontal cortex (PFC) of rhesus monkeys. We report that the spatial characteristics of visual receptive fields between adjacent neurons differed considerably, with increasing heterogeneity from VIP to PFC...
August 11, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28821647/plasticity-beyond-v1-reinforcement-of-motion-perception-upon-binocular-central-retinal-lesions-in-adulthood
#5
Kalina Burnat, Tjing-Tjing Hu, Małgorzata Kossut, Ulf T Eysel, Lutgarde Arckens
Induction of a central retinal lesion in both eyes of adult mammals is a model for macular degeneration and leads to retinotopic map reorganization in the primary visual cortex (V1). Here we characterized the spatio-temporal dynamics of molecular activity levels in the central and peripheral representation of five higher order visual areas, V2/18, V3/19, V4/21a,V5/PMLS, area 7, and V1/17, in adult cats with central 10° retinal lesions (both sexes), by means of real-time PCR for the neuronal activity reporter gene zif268...
August 16, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28817581/population-activity-structure-of-excitatory-and-inhibitory-neurons
#6
Sean R Bittner, Ryan C Williamson, Adam C Snyder, Ashok Litwin-Kumar, Brent Doiron, Steven M Chase, Matthew A Smith, Byron M Yu
Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons...
2017: PloS One
https://www.readbyqxmd.com/read/28815879/calibrated-imaging-reveals-altered-grey-matter-metabolism-related-to-white-matter-microstructure-and-symptom-severity-in-multiple-sclerosis
#7
Nicholas A Hubbard, Monroe P Turner, Minhui Ouyang, Lyndahl Himes, Binu P Thomas, Joanna L Hutchison, Shawheen Faghihahmadabadi, Scott L Davis, Jeremy F Strain, Jeffrey Spence, Daniel C Krawczyk, Hao Huang, Hanzhang Lu, John Hart, Teresa C Frohman, Elliot M Frohman, Darin T Okuda, Bart Rypma
Multiple sclerosis (MS) involves damage to white matter microstructures. This damage has been related to grey matter function as measured by standard, physiologically-nonspecific neuroimaging indices (i.e., blood-oxygen-level dependent signal [BOLD]). Here, we used calibrated functional magnetic resonance imaging and diffusion tensor imaging to examine the extent to which specific, evoked grey matter physiological processes were associated with white matter diffusion in MS. Evoked changes in BOLD, cerebral blood flow (CBF), and oxygen metabolism (CMRO2 ) were measured in visual cortex...
August 16, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28814675/retinal-amyloid-pathology-and-proof-of-concept-imaging-trial-in-alzheimer-s-disease
#8
Yosef Koronyo, David Biggs, Ernesto Barron, David S Boyer, Joel A Pearlman, William J Au, Shawn J Kile, Austin Blanco, Dieu-Trang Fuchs, Adeel Ashfaq, Sally Frautschy, Gregory M Cole, Carol A Miller, David R Hinton, Steven R Verdooner, Keith L Black, Maya Koronyo-Hamaoui
BACKGROUND: Noninvasive detection of Alzheimer's disease (AD) with high specificity and sensitivity can greatly facilitate identification of at-risk populations for earlier, more effective intervention. AD patients exhibit a myriad of retinal pathologies, including hallmark amyloid β-protein (Aβ) deposits. METHODS: Burden, distribution, cellular layer, and structure of retinal Aβ plaques were analyzed in flat mounts and cross sections of definite AD patients and controls (n = 37)...
August 17, 2017: JCI Insight
https://www.readbyqxmd.com/read/28811255/cortical-layers-cyto-myelo-receptor-and-synaptic-architecture-in-human-cortical-areas
#9
REVIEW
Nicola Palomero-Gallagher, Karl Zilles
Cortical layers have classically been identified by their distinctive and prevailing cell types and sizes, as well as the packing densities of cell bodies or myelinated fibers. The densities of multiple receptors for classical neurotransmitters also vary across the depth of the cortical ribbon, and thus determine the neurochemical properties of cyto- and myeloarchitectonic layers. However, a systematic comparison of the correlations between these histologically definable layers and the laminar distribution of transmitter receptors is currently lacking...
August 12, 2017: NeuroImage
https://www.readbyqxmd.com/read/28808597/visual-evoked-potentials-in-primary-open-angle-glaucoma
#10
Mukesh Kumar Jha, Dilip Thakur, Nirmala Limbu, Badri Prasad Badhu, Bishnu Hari Paudel
BACKGROUND AND AIMS: Visual evoked potentials (VEPs) assess the integrity of the visual pathways from the optic nerve to the occipital cortex. Optic disc cupping and visual field loss have been associated with prolongation of latency of VEP in primary open angle glaucoma (POAG). METHODS: Pattern reversal and flash VEP tests were done in consenting 20 primary open angle glaucoma eyes and 40 normal control eyes. RESULTS: In POAG cases, the refractive error [3...
2017: Journal of Neurodegenerative Diseases
https://www.readbyqxmd.com/read/28808026/superior-colliculus-encodes-visual-saliency-before-the-primary-visual-cortex
#11
Brian J White, Janis Y Kan, Ron Levy, Laurent Itti, Douglas P Munoz
Models of visual attention postulate the existence of a bottom-up saliency map that is formed early in the visual processing stream. Although studies have reported evidence of a saliency map in various cortical brain areas, determining the contribution of phylogenetically older pathways is crucial to understanding its origin. Here, we compared saliency coding from neurons in two early gateways into the visual system: the primary visual cortex (V1) and the evolutionarily older superior colliculus (SC). We found that, while the response latency to visual stimulus onset was earlier for V1 neurons than superior colliculus superficial visual-layer neurons (SCs), the saliency representation emerged earlier in SCs than in V1...
August 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28801826/brain-activity-changes-in-somatosensory-and-emotion-related-areas-with-medial-patellofemoral-ligament-deficiency
#12
Masaru Kadowaki, Taku Tadenuma, Nobuyuki Kumahashi, Yuji Uchio
BACKGROUND: Patellar instability with medial patellofemoral ligament (MPFL) deficiency is a common sports injury among young people. Although nonoperative and surgical treatment can provide stability of the patella, patients often have anxiety related to the knee. We speculate that neural dysfunction may be related to anxiety in these patients; however, the mechanism in the brain that generates this anxiety remains unknown. QUESTIONS/PURPOSES: (1) How does brain activity in patients with MPFL deficiency change in the areas related to somatic sensation against lateral shift of the patella? (2) How does patella instability, which can lead to continuous fear or apprehension for dislocation, influence brain activity in the areas related to emotion? METHODS: Nineteen patients with MPFL deficiency underwent surgical reconstruction in our hospital from April 2012 to March 2014...
August 11, 2017: Clinical Orthopaedics and related Research
https://www.readbyqxmd.com/read/28801252/measuring-the-effects-of-attention-to-individual-fingertips-in-somatosensory-cortex-using-ultra-high-field-7t-fmri
#13
Alexander M Puckett, Saskia Bollmann, Markus Barth, Ross Cunnington
Attention to sensory information has been shown to modulate the neuronal processing of that information. For example, visuospatial attention acts by modulating responses at retinotopically appropriate regions of visual cortex (Puckett and DeYoe, 2015; Tootell et al. 1998). Much less, however, is known about the neuronal processing associated with attending to other modalities of sensory information. One reason for this is that visual cortex is relatively large, and therefore easier to access non-invasively in humans using tools such as functional magnetic resonance imaging (fMRI)...
August 8, 2017: NeuroImage
https://www.readbyqxmd.com/read/28794459/multiple-excitatory-actions-of-orexins-upon-thalamo-cortical-neurons-in-dorsal-lateral-geniculate-nucleus-implications-for-vision-modulation-by-arousal
#14
Lukasz Chrobok, Katarzyna Palus-Chramiec, Anna Chrzanowska, Mariusz Kepczynski, Marian Henryk Lewandowski
The orexinergic system of the lateral hypothalamus plays a crucial role in maintaining wakefulness and mediating arousal in a circadian time-dependent manner. Due to the extensive connections of orexinergic neurons, both orexins (OXA and OXB) exert mainly excitatory effects upon remote brain areas, including the thalamus. The dorsal lateral geniculate nucleus (DLG) is a relay thalamic centre for the visual system. Its thalamo-cortical (TC) neurons convey photic information from the retina to the primary visual cortex...
August 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28794407/focal-cortical-seizures-start-as-standing-waves-and-propagate-respecting-homotopic-connectivity
#15
L Federico Rossi, Robert C Wykes, Dimitri M Kullmann, Matteo Carandini
Focal epilepsy involves excessive cortical activity that propagates both locally and distally. Does this propagation follow the same routes as normal cortical activity? We pharmacologically induced focal seizures in primary visual cortex (V1) of awake mice, and compared their propagation to the retinotopic organization of V1 and higher visual areas. We used simultaneous local field potential recordings and widefield imaging of a genetically encoded calcium indicator to measure prolonged seizures (ictal events) and brief interictal events...
August 9, 2017: Nature Communications
https://www.readbyqxmd.com/read/28791331/temporal-processing-in-the-visual-cortex-of-the-awake-and-anesthetized-rat
#16
Ida E J Aasebø, Mikkel E Lepperød, Maria Stavrinou, Sandra Nøkkevangen, Gaute Einevoll, Torkel Hafting, Marianne Fyhn
The activity pattern and temporal dynamics within and between neuron ensembles are essential features of information processing and believed to be profoundly affected by anesthesia. Much of our general understanding of sensory information processing, including computational models aimed at mathematically simulating sensory information processing, rely on parameters derived from recordings conducted on animals under anesthesia. Due to the high variety of neuronal subtypes in the brain, population-based estimates of the impact of anesthesia may conceal unit- or ensemble-specific effects of the transition between states...
July 2017: ENeuro
https://www.readbyqxmd.com/read/28782899/neural-predictors-of-motor-control-and-impact-of-visuo-proprioceptive-information-in-youth
#17
Sharissa H A Corporaal, Jolien Gooijers, Sima Chalavi, Boris Cheval, Stephan P Swinnen, Matthieu P Boisgontier
For successful motor control, the central nervous system is required to combine information from the environment and the current body state, which is provided by vision and proprioception respectively. We investigated the relative contribution of visual and proprioceptive information to upper limb motor control and the extent to which structural brain measures predict this performance in youth (n = 40; age range 9-18 years). Participants performed a manual tracking task, adopting in-phase and anti-phase coordination modes...
August 7, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28777059/modality-specific-changes-in-motor-cortex-excitability-after-visuo-proprioceptive-realignment
#18
Felipe Munoz-Rubke, Jasmine L Mirdamadi, Anna K Lynch, Hannah J Block
Spatial realignment of visual and proprioceptive estimates of hand position is necessary both to keep the estimates in register over time and to compensate for sensory perturbations. Such realignment affects perceived hand position, which the brain must use to plan hand movements. We would therefore expect visuo-proprioceptive realignment to affect the motor system at some level, but the physiological basis of this interaction is unknown. Here, we asked whether activity in primary motor cortex (M1), a well-known substrate of motor control, shows evidence of change after visuo-proprioceptive realignment...
August 4, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/28771634/regional-gray-matter-correlates-of-memory-for-emotion-laden-words-in-middle-aged-and-older-adults-a-voxel-based-morphometry-study
#19
Carina Saarela, Juho Joutsa, Matti Laine, Riitta Parkkola, Juha O Rinne, Mira Karrasch
Emotional content is known to enhance memory in a content-dependent manner in healthy populations. In middle-aged and older adults, a reduced preference for negative material, or even an enhanced preference for positive material has been observed. This preference seems to be modulated by the emotional arousal that the material evokes. The neuroanatomical basis for emotional memory processes is, however, not well understood in middle-aged and older healthy people. Previous research on local gray matter correlates of emotional memory in older populations has mainly been conducted with patients suffering from various neurodegenerative diseases...
2017: PloS One
https://www.readbyqxmd.com/read/28769042/local-opposite-orientation-preferences-in-v1-fmri-sensitivity-to-fine-grained-pattern-information
#20
Arjen Alink, Alexander Walther, Alexandra Krugliak, Nikolaus Kriegeskorte
The orientation of a visual grating can be decoded from human primary visual cortex (V1) using functional magnetic resonance imaging (fMRI) at conventional resolutions (2-3 mm voxel width, 3T scanner). It is unclear to what extent this information originates from different spatial scales of neuronal selectivity, ranging from orientation columns to global areal maps. According to the global-areal-map account, fMRI orientation decoding relies exclusively on fMRI voxels in V1 exhibiting a radial or vertical preference...
August 2, 2017: Scientific Reports
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