scholarly journals Effects of enucleation on the direct reciprocal corticocortical connections between primary visual and somatosensory cortices of the mouse

2019 ◽  
Author(s):  
Ian Omer Massé ◽  
Gilles Bronchti ◽  
Denis Boire
Keyword(s):  
Visual Cortex ◽  
Somatosensory Cortex ◽  
Cortical Layer ◽  
Relative Reduction ◽  
Somatosensory Cortices ◽  
Laminar Distribution ◽  
Multisensory Convergence ◽  
Sensory Cortices ◽  
The Relationship ◽  
Axonal Swellings

AbstractMultisensory convergence is present in the cerebral cortex even at the initial stages of processing in the primary and low-level sensory cortices. Direct connections between primary sensory cortices are a particular feature of rodent cortical connectivity. Our previous studies have shown asymmetric projections between the primary visual and somatosensory cortices in mice. Binocular enucleation produces a relative reduction of the projections from the somatosensory cortex to the visual cortex in mice. The purpose of this study is to compare the direct reciprocal cross-modal connections between the primary visual (V1) and somatosensory (S1) cortices in intact and enucleated C57Bl/6 mice, and to determine quantitative differences in the proportion and laminar distribution of neurons and terminals in these projections. CTB labeled neurons were used to estimate the relative importance of projections between V1 and S1, and their laminar distribution used to classify them as feedback, feedforward or lateral projections. The size of axonal swellings was measured and frequency distribution determined for each cortical layer. Axon diameters were also sampled in these connections. Injections in V1 resulted in a reduced proportion of labeled cells in S1 of enucleated mice. There was a relative decrease of the projection from the somatosensory cortex to the visual cortex in enucleated mice due to a greater relative reduction of supragranular layers neurons. Enucleation otherwise had no effect on the connectivity of the somatosensory cortex with other motor and somatosensory cortices. In the projection from the visual to the somatosensory cortex in enucleated mice, the size of axonal swellings was reduced in all layers. Conversely, in the projection from the somatosensory cortex to the visual cortex, some larger swellings appeared in the supragranular layers. This shows pathway and laminar specific changes in cortical circuitry following loss of sensory afferent activity that results in changes in the relationship between visual and somatosensory cortices in the enucleated mice.

scholarly journals Massive cortical reorganization in sighted Braille readers

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Katarzyna Siuda-Krzywicka ◽  
Łukasz Bola ◽  
Małgorzata Paplińska ◽  
Ewa Sumera ◽  
Katarzyna Jednoróg ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Large Scale ◽  
Reading Speed ◽  
Brain Activity ◽  
Adult Brain ◽  
Cortical Reorganization ◽  
Definitive Evidence ◽  
Visual Word Form Area ◽  
Somatosensory Cortices ◽  
Sensory Cortices

The brain is capable of large-scale reorganization in blindness or after massive injury. Such reorganization crosses the division into separate sensory cortices (visual, somatosensory...). As its result, the visual cortex of the blind becomes active during tactile Braille reading. Although the possibility of such reorganization in the normal, adult brain has been raised, definitive evidence has been lacking. Here, we demonstrate such extensive reorganization in normal, sighted adults who learned Braille while their brain activity was investigated with fMRI and transcranial magnetic stimulation (TMS). Subjects showed enhanced activity for tactile reading in the visual cortex, including the visual word form area (VWFA) that was modulated by their Braille reading speed and strengthened resting-state connectivity between visual and somatosensory cortices. Moreover, TMS disruption of VWFA activity decreased their tactile reading accuracy. Our results indicate that large-scale reorganization is a viable mechanism recruited when learning complex skills.

scholarly journals Dispositional empathy predicts primary somatosensory cortex activity while receiving touch by a hand

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michael Schaefer ◽  
Anja Kühnel ◽  
Franziska Rumpel ◽  
Matti Gärtner
Keyword(s):  
Somatosensory Cortex ◽  
Anterior Cingulate ◽  
Primary Somatosensory Cortex ◽  
Rubber Hand ◽  
Somatosensory Cortices ◽  
Touch Perception ◽  
Trait Empathy ◽  
Human Perceptions ◽  
Dispositional Empathy

AbstractPrevious research revealed an active network of brain areas such as insula and anterior cingulate cortex when witnessing somebody else in pain and feeling empathy. But numerous studies also suggested a role of the somatosensory cortices for state and trait empathy. While recent studies highlight the role of the observer’s primary somatosensory cortex when seeing painful or nonpainful touch, the interaction of somatosensory cortex activity with empathy when receiving touch on the own body is unknown. The current study examines the relationship of touch related somatosensory cortex activity with dispositional empathy by employing an fMRI approach. Participants were touched on the palm of the hand either by the hand of an experimenter or by a rubber hand. We found that the BOLD responses in the primary somatosensory cortex were associated with empathy personality traits personal distress and perspective taking. This relationship was observed when participants were touched both with the experimenter’s real hand or a rubber hand. What is the reason for this link between touch perception and trait empathy? We argue that more empathic individuals may express stronger attention both to other’s human perceptions as well as to the own sensations. In this way, higher dispositional empathy levels might enhance tactile processing by top-down processes. We discuss possible implications of these findings.

scholarly journals Astrocytic modulation of information processing by layer 5 pyramidal neurons of the mouse visual cortex

2020 ◽  
Author(s):  
Dimitri Ryczko ◽  
Maroua Hanini-Daoud ◽  
Steven Condamine ◽  
Benjamin J. B. Bréant ◽  
Maxime Fougère ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cortical Neurons ◽  
Calcium Binding ◽  
Pyramidal Neurons ◽  
Binding Protein ◽  
Contextual Information ◽  
Dendritic Tree ◽  
Cortical Layer ◽  
List Type ◽  
Ionic Environment

AbstractThe most complex cerebral functions are performed by the cortex which most important output is carried out by its layer 5 pyramidal neurons. Their firing reflects integration of sensory and contextual information that they receive. There is evidence that astrocytes influence cortical neurons firing through the release of gliotransmitters such as ATP, glutamate or GABA. These effects were described at the network and at the synaptic levels, but it is still unclear how astrocytes influence neurons input-output transfer function at the cellular level. Here, we used optogenetic tools coupled with electrophysiological, imaging and anatomical approaches to test whether and how astrocytic activation affected processing and integration of distal inputs to layer 5 pyramidal neurons (L5PN). We show that optogenetic activation of astrocytes near L5PN cell body prolonged firing induced by distal inputs to L5PN and potentiated their ability to trigger spikes. The observed astrocytic effects on L5PN firing involved glutamatergic transmission to some extent but relied on release of S100β, an astrocytic Ca2+-binding protein that decreases extracellular Ca2+ once released. This astrocyte-evoked decrease of extracellular Ca2+ elicited firing mediated by activation of Nav1.6 channels. Our findings suggest that astrocytes contribute to the cortical fundamental computational operations by controlling the extracellular ionic environment.Key Points SummaryIntegration of inputs along the dendritic tree of layer 5 pyramidal neurons is an essential operation as these cells represent the most important output carrier of the cerebral cortex. However, the contribution of astrocytes, a type of glial cell to these operations is poorly documented.Here we found that optogenetic activation of astrocytes in the vicinity of layer 5 in the mouse primary visual cortex induce spiking in local pyramidal neurons through Nav1.6 ion channels and prolongs the responses elicited in these neurons by stimulation of their distal inputs in cortical layer 1.This effect partially involved glutamatergic signalling but relied mostly on the astrocytic calcium-binding protein S100β, which regulates the concentration of calcium in the extracellular space around neurons.These findings show that astrocytes contribute to the fundamental computational operations of the cortex by acting on the ionic environment of neurons.

scholarly journals Visual exposure optimizes stimulus encoding in primary visual cortex

2018 ◽  
Author(s):  
Andreea Lazar ◽  
Chris Lewis ◽  
Pascal Fries ◽  
Wolf Singer ◽  
Danko Nikolić
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Neuronal Response ◽  
Extended Period ◽  
Sensory Cells ◽  
Neuronal Populations ◽  
Visual Exposure ◽  
Early Visual Cortex ◽  
Sensory Cortices

SummarySensory exposure alters the response properties of individual neurons in primary sensory cortices. However, it remains unclear how these changes affect stimulus encoding by populations of sensory cells. Here, recording from populations of neurons in cat primary visual cortex, we demonstrate that visual exposure enhances stimulus encoding and discrimination. We find that repeated presentation of brief, high-contrast shapes results in a stereotyped, biphasic population response consisting of a short-latency transient, followed by a late and extended period of reverberatory activity. Visual exposure selectively improves the stimulus specificity of the reverberatory activity, by increasing the magnitude and decreasing the trial-to-trial variability of the neuronal response. Critically, this improved stimulus encoding is distributed across the population and depends on precise temporal coordination. Our findings provide evidence for the existence of an exposure-driven optimization process that enhances the encoding power of neuronal populations in early visual cortex, thus potentially benefiting simple readouts at higher stages of visual processing.

Developmental regulation of plasticity in cat somatosensory cortex

1994 ◽  
Vol 72 (4) ◽  
pp. 1706-1716 ◽  
Author(s):  
S. L. Juliano ◽  
D. E. Eslin ◽  
M. Tommerdahl
Keyword(s):  
Somatosensory Cortex ◽  
Sensory Input ◽  
Developmental Regulation ◽  
Normal Pattern ◽  
Metabolic Pattern ◽  
Somatosensory Cortices ◽  
Experimental Side ◽  
Adult Cats ◽  
Evoked Activity ◽  
The Individual

1. The neocortical response to deprivation of somatic sensory input in young animals of different ages was compared with the same manipulation in adults. The response was measured through the use of 2-deoxyglucose (2DG) mapping. Although several features of the cortical response were similar in animals of all ages, the metabolic patterns evoked by somatic stimulation differed substantially from each other at all ages. 2. When adult cats receive a digit amputation and survive from 2 to 8 wk, the pattern of stimulus-evoked metabolic uptake expands dramatically in the somatosensory cortex contralateral to the deprived forepaw. Comparisons between the normal and experimental somatosensory cortices reveal that the distribution of activity on the experimental side was roughly an expanded version of the normal pattern. 3. Unilateral digit amputations of digit 2 were conducted on kittens 2, 4, or 6 wk old. They survived until 3–4 mo and then received a 2DG experiment, during which digit 3 was stimulated bilaterally. Evaluation of the evoked metabolic pattern indicated substantial differences from the activity elicited in adults undergoing identical manipulations. 4. The individual patches of activity that made up the metabolic pattern were similar in intensity in both hemispheres when the digit amputation was conducted at either 2, 4, or 6 wk. After a digit amputation at 2 wk, the patches were significantly narrower in the experimental hemisphere; after a digit amputation at 6 wk, the patches were significantly wider in the hemisphere receiving from the deprived forepaw. 5. Two-dimensional maps of 2DG uptake in areas 3b and 1 of the somatosensory cortex reveal that after a digit amputation at 2, 4, or 6 wk, the distribution of activity in the hemisphere receiving from the digit amputation was more dispersed and widespread than in the normal hemisphere. The dispersed pattern of uptake was not an expanded version of the normal pattern, but scattered over a wider region of somatosensory cortex. This observation is similar to the normal pattern of evoked activity seen in developing animals. 6. The total area of 2DG uptake in the somatosensory cortex contralateral to a digit amputation conducted at 2 or 4 wk was not greater than that in the normal hemisphere, even though it was more widespread. After a digit amputation at 6 wk, however, the area of evoked activity was greater in the experimental hemisphere but not of the magnitude as the same manipulation in an adult.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Subdomains within orientation columns of primary visual cortex

2019 ◽  
Vol 5 (6) ◽  
pp. eaaw0807 ◽  
Author(s):  
Ming Li ◽  
Xue Mei Song ◽  
Tao Xu ◽  
Dewen Hu ◽  
Anna Wang Roe ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Accurate Method ◽  
Electrode Position ◽  
Tree Shrews ◽  
Form Processing ◽  
Orientation Columns ◽  
Relationship Of ◽  
First Time ◽  
The Relationship

In the mammalian visual system, early stages of visual form processing begin with orientation-selective neurons in primary visual cortex (V1). In many species (including humans, monkeys, tree shrews, cats, and ferrets), these neurons are organized in a beautifully arrayed pinwheel-like orientation columns, which shift in orientation preference across V1. However, to date, the relationship of orientation architecture to the encoding of multiple elemental aspects of visual contours is still unknown. Here, using a novel, highly accurate method of targeting electrode position, we report for the first time the presence of three subdomains within single orientation domains. We suggest that these zones subserve computation of distinct aspects of visual contours and propose a novel tripartite pinwheel-centered view of an orientation hypercolumn.

scholarly journals Erratum to: Volume Electron Microscopy Study of the Relationship Between Synapses and Astrocytes in the Developing Rat Somatosensory Cortex

2020 ◽  
Vol 30 (5) ◽  
pp. 3427-3428
Author(s):  
Toko Kikuchi ◽  
Juncal Gonzalez-Soriano ◽  
Asta Kastanauskaite ◽  
Ruth Benavides-Piccione ◽  
Angel Merchan-Perez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Somatosensory Cortex ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Rat Somatosensory Cortex ◽  
The Relationship ◽  
Developing Rat ◽  
Volume Electron Microscopy

Auditory modulation of oscillatory activity in extra-striate visual cortex and its contribution to audio–visual multisensory integration: A human intracranial EEG study

2012 ◽  
Vol 25 (0) ◽  
pp. 198
Author(s):  
Manuel R. Mercier ◽  
John J. Foxe ◽  
Ian C. Fiebelkorn ◽  
John S. Butler ◽  
Theodore H. Schwartz ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Multisensory Integration ◽  
Multisensory Processing ◽  
Brain Activity ◽  
Visual Stimuli ◽  
Additive Model ◽  
Oscillatory Activity ◽  
Time Frequency ◽  
Electrical Brain Activity ◽  
Sensory Cortices

Investigations have traditionally focused on activity in the sensory cortices as a function of their respective sensory inputs. However, converging evidence from multisensory research has shown that neural activity in a given sensory region can be modulated by stimulation of other so-called ancillary sensory systems. Both electrophysiology and functional imaging support the occurrence of multisensory processing in human sensory cortex based on the latency of multisensory effects and their precise anatomical localization. Still, due to inherent methodological limitations, direct evidence of the precise mechanisms by which multisensory integration occurs within human sensory cortices is lacking. Using intracranial recordings in epileptic patients () undergoing presurgical evaluation, we investigated the neurophysiological basis of multisensory integration in visual cortex. Subdural electrical brain activity was recorded while patients performed a simple detection task of randomly ordered Auditory alone (A), Visual alone (V) and Audio–Visual stimuli (AV). We then performed time-frequency analysis: first we investigated each condition separately to evaluate responses compared to baseline, then we indexed multisensory integration using both the maximum criterion model (AV vs. V) and the additive model (AV vs. A+V). Our results show that auditory input significantly modulates neuronal activity in visual cortex by resetting the phase of ongoing oscillatory activity. This in turn leads to multisensory integration when auditory and visual stimuli are simultaneously presented.

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