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Primary visual cortex

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https://www.readbyqxmd.com/read/29930497/globally-normal-bistable-motion-perception-of-anisometropic-amblyopes-may-profit-from-an-unusual-coding-mechanism
#1
Jiachen Liu, Yifeng Zhou, Tzvetomir Tzvetanov
Anisometropic amblyopia is a neurodevelopmental disorder of the visual system. There is evidence that the neural deficits spread across visual areas, from the primary cortex up to higher brain areas, including motion coding structures such as MT. Here, we used bistable plaid motion to investigate changes in the underlying mechanisms of motion integration and segmentation and, thus, help us to unravel in more detail deficits in the amblyopic visual motion system. Our results showed that (1) amblyopes globally exhibited normal bistable perception in all viewing conditions compared to the control group and (2) decreased contrast led to a stronger increase in percept switches and decreased percept durations in the control group, while the amblyopic group exhibited no such changes...
2018: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/29928655/cortical-alterations-in-phobic-postural-vertigo-a-multimodal-imaging-approach
#2
Pauline Popp, Peter Zu Eulenburg, Thomas Stephan, Rainer Bögle, Maximilian Habs, Peter Henningsen, Regina Feuerecker, Marianne Dieterich
Objective: Functional dizziness syndromes are among the most common diagnoses made in patients with chronic dizziness, but their underlying neural characteristics are largely unknown. The aim of this neuroimaging study was to analyze the disease-specific brain changes in patients with phobic postural vertigo (PPV). Methods: We measured brain morphology, task response, and functional connectivity in 44 patients with PPV and 44 healthy controls. Results: The analyses revealed a relative structural increase in regions of the prefrontal cortex and the associated thalamic projection zones as well as in the primary motor cortex...
June 2018: Annals of Clinical and Translational Neurology
https://www.readbyqxmd.com/read/29915138/oscillatory-encoding-of-visual-stimulus-familiarity
#3
Samuel T Kissinger, Alexandr Pak, Yu Tang, Sotiris C Masmanidis, Alexander A Chubykin
Familiarity of the environment changes the way we perceive and encode incoming information. However, the neural substrates underlying this phenomenon are poorly understood. Here we describe a new form of experience-dependent low frequency oscillations in the primary visual cortex (V1) of awake adult male mice. The oscillations emerged in visually evoked potentials (VEPs) and single-unit activity following repeated visual stimulation. The oscillations were sensitive to the spatial frequency content of a visual stimulus and required the muscarinic acetylcholine receptors (mAChRs) for their induction and expression...
June 18, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29913971/brain-activation-due-to-postoperative-pain-from-the-right-hand-measured-with-regional-cerebral-blood-flow-using-positron-emission-tomography
#4
Torsten Gordh, Bertil Vinnars, Håkan Fischer, Hans Blomberg, Jan Modig, Mats Fredrikson, Per Hartvig
Background Brain activation resulting from acute postoperative pain has to our knowledge not previously been studied using positron emission tomography, except from one case study. The aim of this study was to monitor activation in brain sensory pathways during acute pain after surgery of the hand. A secondary aim was to compare brain activation in clinical postoperative pain to that previously reported, by the same research group, for a model of experimental pain from the same body area. Increase in regional cerebral blood flow (rCBF) is presumed to indicate neuronal activation and decrease in blood flow decreased neuronal firing...
December 29, 2017: Scandinavian Journal of Pain
https://www.readbyqxmd.com/read/29912968/information-spreading-by-a-combination-of-meg-source-estimation-and-multivariate-pattern-classification
#5
Masashi Sato, Okito Yamashita, Masa-Aki Sato, Yoichi Miyawaki
To understand information representation in human brain activity, it is important to investigate its fine spatial patterns at high temporal resolution. One possible approach is to use source estimation of magnetoencephalography (MEG) signals. Previous studies have mainly quantified accuracy of this technique according to positional deviations and dispersion of estimated sources, but it remains unclear how accurately MEG source estimation restores information content represented by spatial patterns of brain activity...
2018: PloS One
https://www.readbyqxmd.com/read/29911971/sensory-cortex-is-optimised-for-prediction-of-future-input
#6
Yosef Singer, Yayoi Teramoto, Ben Db Willmore, Andrew J King, Jan W H Schnupp, Nicol S Harper
Neurons in sensory cortex are tuned to diverse features in natural scenes. But what determines which features neurons become selective to? Here we explore the idea that neuronal selectivity is optimised to represent features in the recent sensory past that best predict immediate future inputs. We tested this hypothesis using simple feedforward neural networks, which were trained to predict the next few video or audio frames in clips of natural scenes. The networks developed receptive fields that closely matched those of real cortical neurons in different mammalian species, including the oriented spatial tuning of primary visual cortex, the frequency selectivity of primary auditory cortex and, most notably, their temporal tuning properties...
June 18, 2018: ELife
https://www.readbyqxmd.com/read/29907863/attenuation-of-retinal-vascular-development-in-neonatal-mice-subjected-to-hypoxic-ischemic-encephalopathy
#7
Ismail S Zaitoun, Ulas Cikla, Dila Zafer, Eshwar Udho, Reem Almomani, Andrew Suscha, Pelin Cengiz, Christine M Sorenson, Nader Sheibani
A significant proportion of children that survive hypoxic-ischemic encephalopathy (HIE) develop visual impairment. These visual deficits are generally attributed to injuries that occur in the primary visual cortex and other visual processing systems. Recent studies suggested that neuronal damage might also occur in the retina. An important structure affecting the viability of retinal neurons is the vasculature. However, the effects of HIE on the retinal neurovasculature have not been systemically evaluated...
June 15, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29906635/learning-of-goal-relevant-and-irrelevant-complex-visual-sequences-in-human-v1
#8
Clive R Rosenthal, Indira Mallik, Cesar Caballero-Gaudes, Martin I Sereno, David Soto
Learning and memory are supported by a network involving the medial temporal lobe and linked neocortical regions. Emerging evidence indicates that primary visual cortex (i.e., V1) may contribute to recognition memory, but this has been tested only with a single visuospatial sequence as the target memorandum. The present study used functional magnetic resonance imaging to investigate whether human V1 can support the learning of multiple, concurrent, and complex visual sequences involving discontinous (second-order) associations...
June 12, 2018: NeuroImage
https://www.readbyqxmd.com/read/29906549/theta-band-eeg-activity-over-sensorimotor-regions-is-modulated-by-expected-visual-reafferent-feedback-during-reach-planning
#9
Benjamin Dufour, François Thénault, Pierre-Michel Bernier
Activity in the primary motor cortex (M1) during reach planning is known to be correlated with the upcoming kinetics and kinematics of the hand. Yet recent work using visual-motor dissociation tasks suggests that M1 activity is also correlated with the visual consequences of an action, independent of the actual hand displacement. The goal of the present work was to investigate whether oscillatory activity over sensorimotor regions is modulated by the expectancy of visual reafferent feedback during reach planning...
June 12, 2018: Neuroscience
https://www.readbyqxmd.com/read/29905116/critical-periods-in-amblyopia
#10
Takao K Hensch, Elizabeth M Quinlan
The shift in ocular dominance (OD) of binocular neurons induced by monocular deprivation is the canonical model of synaptic plasticity confined to a postnatal critical period. Developmental constraints on this plasticity not only lend stability to the mature visual cortical circuitry but also impede the ability to recover from amblyopia beyond an early window. Advances with mouse models utilizing the power of molecular, genetic, and imaging tools are beginning to unravel the circuit, cellular, and molecular mechanisms controlling the onset and closure of the critical periods of plasticity in the primary visual cortex (V1)...
January 2018: Visual Neuroscience
https://www.readbyqxmd.com/read/29896093/unilateral-application-of-cathodal-tdcs-reduces-transcallosal-inhibition-and-improves-visual-acuity-in-amblyopic-patients
#11
Tommaso Bocci, Francesco Nasini, Matteo Caleo, Laura Restani, Davide Barloscio, Gianluca Ardolino, Alberto Priori, Lamberto Maffei, Marco Nardi, Ferdinando Sartucci
Objective: Amblyopia is a neurodevelopmental disorder characterized by visual acuity and contrast sensitivity loss, refractory to pharmacological and optical treatments in adulthood. In animals, the corpus callosum (CC) contributes to suppression of visual responses of the amblyopic eye. To investigate the role of interhemispheric pathways in amblyopic patients, we studied the response of the visual cortex to transcranial Direct Current Stimulation (tDCS) applied over the primary visual area (V1) contralateral to the "lazy eye...
2018: Frontiers in Behavioral Neuroscience
https://www.readbyqxmd.com/read/29896087/changes-of-visual-pathway-and-brain-connectivity-in-glaucoma-a-systematic-review
#12
Raffaele Nuzzi, Laura Dallorto, Teresa Rolle
Background: Glaucoma is a leading cause of irreversible blindness worldwide. The increasing interest in the involvement of the cortical visual pathway in glaucomatous patients is due to the implications in recent therapies, such as neuroprotection and neuroregeneration. Objective: In this review, we outline the current understanding of brain structural, functional, and metabolic changes detected with the modern techniques of neuroimaging in glaucomatous subjects. Methods: We screened MEDLINE, EMBASE, CINAHL, CENTRAL, LILACS, Trip Database, and NICE for original contributions published until 31 October 2017...
2018: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/29894888/increased-variability-of-stimulus-driven-cortical-responses-is-associated-with-genetic-variability-in-children-with-and-without-dyslexia
#13
T M Centanni, D Pantazis, D T Truong, J R Gruen, J D E Gabrieli, T P Hogan
Individuals with dyslexia exhibit increased brainstem variability in response to sound. It is unknown as to whether increased variability extends to neocortical regions associated with audition and reading, extends to visual stimuli, and whether increased variability characterizes all children with dyslexia or, instead, a specific subset of children. We evaluated the consistency of stimulus-evoked neural responses in children with (N = 20) or without dyslexia (N = 12) as measured by magnetoencephalography (MEG)...
May 26, 2018: Developmental Cognitive Neuroscience
https://www.readbyqxmd.com/read/29892057/top-down-feedback-controls-spatial-summation-and-response-amplitude-in-primate-visual-cortex
#14
Lauri Nurminen, Sam Merlin, Maryam Bijanzadeh, Frederick Federer, Alessandra Angelucci
Sensory information travels along feedforward connections through a hierarchy of cortical areas, which, in turn, send feedback connections to lower-order areas. Feedback has been implicated in attention, expectation, and sensory context, but the mechanisms underlying these diverse feedback functions are unknown. Using specific optogenetic inactivation of feedback connections from the secondary visual area (V2), we show how feedback affects neural responses in the primate primary visual cortex (V1). Reducing feedback activity increases V1 cells' receptive field (RF) size, decreases their responses to stimuli confined to the RF, and increases their responses to stimuli extending into the proximal surround, therefore reducing surround suppression...
June 11, 2018: Nature Communications
https://www.readbyqxmd.com/read/29885483/detectability-and-reproducibility-of-the-olfactory-fmri-signal-under-the-influence-of-magnetic-susceptibility-artifacts-in-the-primary-olfactory-cortex
#15
Jiaming Lu, Xin Wang, Zhao Qing, Zhu Li, Wen Zhang, Ying Liu, Lihua Yuan, Le Cheng, Ming Li, Bin Zhu, Xin Zhang, Qing X Yang, Bing Zhang
For human olfactory functional MRI studies, the primary olfactory cortex (POC) suffers severe magnetic susceptibility artifacts, which adversely influences the detectability and reproducibility of the olfactory fMRI data and its clinical applications. The goal of this work is to assess the impacts of the image artifacts on the detectability and reproducibility of the olfactory activation in the POC. The severity of artifacts in the POC were classified into three levels using a Subjective Artifact score (SA_score)...
June 6, 2018: NeuroImage
https://www.readbyqxmd.com/read/29881334/emotion-and-the-cardiovascular-system-postulated-role-of-inputs-from-the-medial-prefrontal-cortex-to-the-dorsolateral-periaqueductal-gray
#16
REVIEW
Roger Dampney
The midbrain periaqueductal gray (PAG) plays a major role in generating different types of behavioral responses to emotional stressors. This review focuses on the role of the dorsolateral (dl) portion of the PAG, which on the basis of anatomical and functional studies, appears to have a unique and distinctive role in generating behavioral, cardiovascular and respiratory responses to real and perceived emotional stressors. In particular, the dlPAG, but not other parts of the PAG, receives direct inputs from the primary auditory cortex and from the secondary visual cortex...
2018: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/29881145/accuracy-of-radiographic-determination-of-the-posterior-femoral-wall-integrity-in-anterior-cruciate-ligament-reconstruction
#17
Joshua P Herzog, Edward D Arrington, Creighton C Tubb, Gautham Prabhakar, Nicholas J Zarkadis, Nicholas A Kusnezov
Objective: To evaluate the accuracy of radiographs in determining integrity of the posterior femoral cortex following ACL reconstruction. Methods: Fifty adult volunteers undergoing primary arthroscopic transtibial ACL reconstructions were prospectively enrolled into this study. Plain radiographs and fine-cut CT of the operative knee were obtained post-operatively. Three blinded orthopaedic surgeons were asked to measure the distance from the femoral tunnel to the posterior cortex on lateral radiographs...
June 2018: Journal of Orthopaedics
https://www.readbyqxmd.com/read/29880842/optogenetic-auditory-fmri-reveals-the-effects-of-visual-cortical-inputs-on-auditory-midbrain-response
#18
Alex T L Leong, Celia M Dong, Patrick P Gao, Russell W Chan, Anthea To, Dan H Sanes, Ed X Wu
Sensory cortices contain extensive descending (corticofugal) pathways, yet their impact on brainstem processing - particularly across sensory systems - remains poorly understood. In the auditory system, the inferior colliculus (IC) in the midbrain receives cross-modal inputs from the visual cortex (VC). However, the influences from VC on auditory midbrain processing are unclear. To investigate whether and how visual cortical inputs affect IC auditory responses, the present study combines auditory blood-oxygenation-level-dependent (BOLD) functional MRI (fMRI) with cell-type specific optogenetic manipulation of visual cortex...
June 7, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29876271/regional-microstructural-organization-of-the-cerebral-cortex-is-affected-by-preterm-birth
#19
Marine Bouyssi-Kobar, Marie Brossard-Racine, Marni Jacobs, Jonathan Murnick, Taeun Chang, Catherine Limperopoulos
Objectives: To compare regional cerebral cortical microstructural organization between preterm infants at term-equivalent age (TEA) and healthy full-term newborns, and to examine the impact of clinical risk factors on cerebral cortical micro-organization in the preterm cohort. Study design: We prospectively enrolled very preterm infants (gestational age (GA) at birth<32 weeks; birthweight<1500 g) and healthy full-term controls. Using non-invasive 3T diffusion tensor imaging (DTI) metrics, we quantified regional micro-organization in ten cerebral cortical areas: medial/dorsolateral prefrontal cortex, anterior/posterior cingulate cortex, insula, posterior parietal cortex, motor/somatosensory/auditory/visual cortex...
2018: NeuroImage: Clinical
https://www.readbyqxmd.com/read/29876261/parietofrontal-network-upregulation-after-motor-stroke
#20
M Bönstrup, R Schulz, G Schön, B Cheng, J Feldheim, G Thomalla, C Gerloff
Objective: Motor recovery after stroke shows a high inter-subject variability. The brain's potential to form new connections determines individual levels of recovery of motor function. Most of our daily activities require visuomotor integration, which engages parietal areas. Compared to the frontal motor system, less is known about the parietal motor system's reconfiguration related to stroke recovery. Here, we tested if functional connectivity among parietal and frontal motor areas undergoes plastic changes after stroke and assessed the behavioral relevance for motor function after stroke...
2018: NeuroImage: Clinical
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