Search results for "cortex"
showing 10 items of 1827 documents
Evidence of neuroplasticity in the human visual cortex following beneficial anti-VEGF treatment in exudative age-related macular degeneration
2012
Purpose Anti-vascular endothelial growth factor (VEGF) agents have been shown to improve visual acuity and prevent vision loss in exudative age-related macular degeneration (AMD). As the vision improves relatively quickly in response to intravitreal injections, we wanted to know whether this improvement is reflected in electrophysiolocal markers of visual cortical processing. Methods Our interventional case series included 6 elderly patients who underwent injection treatment to the affected eye. Their visual acuity, tomographic images of retinal thickness and visual evoked potentials (VEP) were assessed before of the treatment and six weeks after the last injection. Results All patients sho…
Seeing with the visual cortex
1984
A short analysis of the input-output organization of the primary visual cortical areas in the cat and monkey is followed by a description of the salient microelectrophysiological properties of retino-geniculo-cortical system neurons. It is concluded that a strict hierarchical model of cortical processing of visual information is no longer tenable.
Relationship between physiological excitatory and inhibitory measures of excitability in the left vs. right human motor cortex and peripheral electro…
2017
Abstract The current study was aimed at investigating the relationships of excitatory and inhibitory circuits of the left vs. right primary motor cortex with peripheral electrodermal activity (EDA). Ten healthy subjects participated in two experimental sessions. In each session, EDA was recorded for 10 min from the palmar surface of the left hand. Immediately after EDA recording, Transcranial Magnetic Stimulation (TMS) was used to probe excitatory and inhibitory circuits of the left or right primary motor cortex using two protocols of stimulation: the input-output curve for recording of motor evoked potentials, for testing excitatory circuits; the long-interval cortical inhibition (LICI) pr…
Channeled scaffolds implanted in adult rat brain.
2012
Scaffolds with aligned channels based on acrylate copolymers, which had previously demonstrated good com- patibility with neural progenitor cells were studied as coloniz- able structures both in vitro with neural progenitor cells and in vivo, implanted without cells in two different locations, in the cortical plate of adult rat brains and close to the subven- tricular zone. In vitro, neuroprogenitors colonize the scaffold and differentiate into neurons and glia within its channels. When implanted in vivo immunohistochemical analysis by confocal microscopy for neural and endothelial cells markers demonstrated that the scaffolds maintained continuity with the surrounding neural tissue and wer…
Integration of Gravitational Torques in Cerebellar Pathways Allows for the Dynamic Inverse Computation of Vertical Pointing Movements of a Robot Arm
2008
BackgroundSeveral authors suggested that gravitational forces are centrally represented in the brain for planning, control and sensorimotor predictions of movements. Furthermore, some studies proposed that the cerebellum computes the inverse dynamics (internal inverse model) whereas others suggested that it computes sensorimotor predictions (internal forward model).Methodology/principal findingsThis study proposes a model of cerebellar pathways deduced from both biological and physical constraints. The model learns the dynamic inverse computation of the effect of gravitational torques from its sensorimotor predictions without calculating an explicit inverse computation. By using supervised …
Spinothalamic and thalamocortical nociceptive pathways
2002
The concept that the perception of a stimulus as being painful requires activity in parts of the cerebral cortex has gained universal recognition within the past 10 years. 28 The large number of functional imaging studies in humans, appearing during that period, have greatly contributed to this development by showing consistent evidence for activation of various cortical areas by painful stimuli, including the primary and secondary somatosensory cortex, the insula, the anterior cingulate gyrus, and prefrontal cortical areas. Thus, the sense of pain—like all other senses— has a representation within the cerebral cortex. These imaging studies, however, did not reveal the pathways by which a p…
Prior precision modulates the minimisation of prediction error in human auditory cortex
2018
AbstractThe predictive coding model of perception proposes that successful representation of the perceptual world depends upon cancelling out the discrepancy between prediction and sensory input (i.e., prediction error). Recent studies further suggest a distinction between prediction error associated with non-predicted stimuli of different prior precision (i.e., inverse variance). However, it is not fully understood how prediction error from different precision levels is minimised in the predictive process. The current research used magnetoencephalography (MEG) to examine whether prior precision modulates the cortical dynamics of the making of perceptual inferences. We presented participant…
Migraine as a Cortical Brain Disorder
2020
Purpose Migraine is an exclusively human chronic disorder with ictal manifestations characterized by a multifaceted clinical complexity pointing to a cerebral cortical involvement. The present review is aimed to cover the clinical, neuroimaging, and neurophysiological literature on the role of the cerebral cortex in migraine pathophysiology. Overview Converging clinical scenarios, advanced neuroimaging data, and experimental neurophysiological findings, indicate that fluctuating excitability, plasticity, and metabolism of cortical neurons represent the pathophysiological substrate of the migraine cycle. Abnormal cortical responsivity and sensory processing coupled to a mismatch between the …
Neurobiological foundations of multisensory processing integration in people with autism spectrum disorders: The role of the medial prefrontal cortex
2014
This review aims to relate the sensory processing problems in people with Autism spectrum disorders (ASD), especially Multisensory interaction (MSI), to the role of the medial prefrontal cortex (mPFC) by exploring neuroanatomical findings; brain connectivity and Default Network (DN); global or locally directed attention; and temporal multisensory binding. The mPFC is part of the brain’s DN, which is deactivated when attention is focused on a particular task and activated on rest when spontaneous cognition emerges. In those with ASD, it is hypoactive and the higher the social impairment the greater the atypical activity. With an immature DN, cross-modal integration is impaired, resulting in …
Neural Mechanisms Underlying Human Auditory Evoked Responses Revealed By Human Neocortical Neurosolver
2022
Funding Information: This study was supported by National Institutes of Health (Grant Nos. NIBIB RO1 EB022889, NIMH RO1 MH106174). Publisher Copyright: © 2021, The Author(s). Auditory evoked fields (AEFs) are commonly studied, yet their underlying neural mechanisms remain poorly understood. Here, we used the biophysical modelling software Human Neocortical Neurosolver (HNN) whose foundation is a canonical neocortical circuit model to interpret the cell and network mechanisms contributing to macroscale AEFs elicited by a simple tone, measured with magnetoencephalography. We found that AEFs can be reproduced by activating the neocortical circuit through a layer specific sequence of feedforwar…