Probing effects of visual motion adaptation on primary visual cortex (V1) excitability using Tms in Bilateral Vestibular Failure (Bvf) patients

2015 ◽  
Vol 357 ◽  
pp. e172
Author(s):  
H. Ahmad ◽  
R.E. Roberts ◽  
Q. Arshad ◽  
M. Patel ◽  
A.M. Bronstein
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Motion ◽  
Motion Adaptation

scholarly journals A Theory of the Visual Motion Coding in the Primary Visual Cortex

1996 ◽  
Vol 8 (4) ◽  
pp. 705-730 ◽  
Author(s):  
Zhaoping Li
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Motion ◽  
Ocular Dominance ◽  
Phase Relationship ◽  
Field Size ◽  
Color Channel ◽  
Cortical Cells ◽  
Motion Direction ◽  
Motion Coding

This paper demonstrates that much of visual motion coding in the primary visual cortex can be understood from a theory of efficient motion coding in a multiscale representation. The theory predicts that cortical cells can have a spectrum of directional indices, be tuned to different directions of motion, and have spatiotemporally separable or inseparable receptive fields (RF). The predictions also include the following correlations between motion coding and spatial, chromatic, and stereo codings: the preferred speed is greater when the cell receptive field size is larger, the color channel prefers lower speed than the luminance channel, and both the optimal speeds and the preferred directions of motion can be different for inputs from different eyes to the same neuron. These predictions agree with experimental observations. In addition, this theory makes predictions that have not been experimentally investigated systematically and provides a testing ground for an efficient multiscale coding framework. These predictions are as follows: (1) if nearby cortical cells of a given preferred orientation and scale prefer opposite directions of motion and have a quadrature RF phase relationship with each other, then they will have the same directional index, (2) a single neuron can have different optimal motion speeds for opposite motion directions of monocular stimuli, and (3) a neuron's ocular dominance may change with motion direction if the neuron prefers opposite directions for inputs from different eyes.

scholarly journals The Role of Spared Calcarine Cortex and Lateral Occipital Cortex in the Responses of Human Hemianopes to Visual Motion

2004 ◽  
Vol 16 (2) ◽  
pp. 204-218 ◽  
Author(s):  
Antony B. Morland ◽  
Sandra Lê ◽  
Erin Carroll ◽  
Michael B. Hoffmann ◽  
Alidz Pambakian
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Motion ◽  
Neural Mechanism ◽  
Visual Pathways ◽  
The Other ◽  
Visual Response ◽  
Visual Responses ◽  
Behavioral Experiments ◽  
Residual Vision

Some patients, who are rendered perimetrically blind in one hemifield by cortical lesions, nevertheless exhibit residual visual capacities within their field defects. The neural mechanism that mediates the residual visual responses has remained the topic of considerable debate. One explanation posits the subcortical visual pathways that bypass the primary visual cortex and innervate the extrastriate visual areas as the substrate that underlies the residual vision. The other explanation is that small islands of the primary visual cortex remain intact and provide the signals for residual vision. We have performed behavioral and functional magnetic resonance imaging experiments to investigate the validity of the two explanations of residual vision. Our behavioral experiments indicated that of the seven hemianopes tested, two had the ability to discriminate the direction of a drifting grating. This residual visual response was shown with fMRI to be the result of spared islands of calcarine cortical activity in one of the hemianopes, whereas only lateral occipital activity was documented in the other patient. These results indicate that the underlying neural correlates of residual vision can vary between patients. Moreover, our study emphasizes the necessity of ruling out the presence of islands of preserved function and primary visual cortex before assigning residual visual capacities to the properties of visual pathways that bypass the primary visual cortex.

scholarly journals Differential effect of visual motion adaption upon visual cortical excitability

2017 ◽  
Vol 117 (3) ◽  
pp. 903-909 ◽  
Author(s):  
Astrid J. A. Lubeck ◽  
Angelique Van Ombergen ◽  
Hena Ahmad ◽  
Jelte E. Bos ◽  
Floris L. Wuyts ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Motion ◽  
Cortical Excitability ◽  
Roll Motion ◽  
Subjective Visual Vertical ◽  
Motion Adaptation ◽  
Visual Vertical ◽  
Early Visual Cortex ◽  
Phosphene Threshold ◽  
Visual Cortical

The objectives of this study were 1) to probe the effects of visual motion adaptation on early visual and V5/MT cortical excitability and 2) to investigate whether changes in cortical excitability following visual motion adaptation are related to the degree of visual dependency, i.e., an overreliance on visual cues compared with vestibular or proprioceptive cues. Participants were exposed to a roll motion visual stimulus before, during, and after visual motion adaptation. At these stages, 20 transcranial magnetic stimulation (TMS) pulses at phosphene threshold values were applied over early visual and V5/MT cortical areas from which the probability of eliciting a phosphene was calculated. Before and after adaptation, participants aligned the subjective visual vertical in front of the roll motion stimulus as a marker of visual dependency. During adaptation, early visual cortex excitability decreased whereas V5/MT excitability increased. After adaptation, both early visual and V5/MT excitability were increased. The roll motion-induced tilt of the subjective visual vertical (visual dependence) was not influenced by visual motion adaptation and did not correlate with phosphene threshold or visual cortex excitability. We conclude that early visual and V5/MT cortical excitability is differentially affected by visual motion adaptation. Furthermore, excitability in the early or late visual cortex is not associated with an increase in visual reliance during spatial orientation. Our findings complement earlier studies that have probed visual cortical excitability following motion adaptation and highlight the differential role of the early visual cortex and V5/MT in visual motion processing. NEW & NOTEWORTHY We examined the influence of visual motion adaptation on visual cortex excitability and found a differential effect in V1/V2 compared with V5/MT. Changes in visual excitability following motion adaptation were not related to the degree of an individual's visual dependency.

Complex motion selectivity in PMLS cortex following early lesions of primary visual cortex in the cat

2007 ◽  
Vol 24 (1) ◽  
pp. 53-64 ◽  
Author(s):  
B.G. OUELLETTE ◽  
K. MINVILLE ◽  
D. BOIRE ◽  
M. PTITO ◽  
C. CASANOVA
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Motion ◽  
Neuronal Response ◽  
Temporal Frequency ◽  
Limited Range ◽  
Direction Selectivity ◽  
Motion Processing ◽  
Complex Motion ◽  
Visual Motion Cues

In the cat, the analysis of visual motion cues has generally been attributed to the posteromedial lateral suprasylvian cortex (PMLS) (Toyama et al., 1985; Rauschecker et al., 1987; Rauschecker, 1988; Kim et al., 1997). The responses of neurons in this area are not critically dependent on inputs from the primary visual cortex (VC), as lesions of VC leave neuronal response properties in PMLS relatively unchanged (Spear & Baumann, 1979; Spear, 1988; Guido et al., 1990b). However, previous studies have used a limited range of visual stimuli. In this study, we assessed whether neurons in PMLS cortex remained direction-selective to complex motion stimuli following a lesion of VC, particularly to complex random dot kinematograms (RDKs). Unilateral aspiration of VC was performed on post-natal days 7–9. Single unit extracellular recordings were performed one year later in the ipsilateral PMLS cortex. As in previous studies, a reduction in the percentage of direction selective neurons was observed with drifting sinewave gratings. We report a previously unobserved phenomenon with sinewave gratings, in which there is a greater modulation of firing rate at the temporal frequency of the stimulus in animals with a lesion of VC, suggesting an increased segregation of ON and OFF sub-regions. A significant portion of neurons in PMLS cortex were direction selective to simple (16/18) and complex (11/16) RDKs. However, the strength of direction selectivity to both stimuli was reduced as compared to normals. The data suggest that complex motion processing is still present, albeit reduced, in PMLS cortex despite the removal of VC input. The complex RDK motion selectivity is consistent with both geniculo-cortical and extra-geniculate thalamo-cortical pathways in residual direction encoding.

scholarly journals Changes in visual motion processing by neurons in mature primary visual cortex (V1) following early color deprivation

2016 ◽  
Vol 16 (12) ◽  
pp. 1182
Author(s):  
Heywood Petry ◽  
Wenhao Dang ◽  
Elizabeth Johnson ◽  
Stephen Van Hooser
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Motion ◽  
Motion Processing ◽  
Visual Motion Processing

scholarly journals Visual motion computation in recurrent neural networks

2017 ◽  
Author(s):  
Marius Pachitariu ◽  
Maneesh Sahani
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Information ◽  
Visual Motion ◽  
Hebbian Learning ◽  
Temporal Dynamics ◽  
Temporal Structure ◽  
Receptive Fields ◽  
Learning Rule ◽  
Connectivity Matrix

AbstractPopulations of neurons in primary visual cortex (V1) transform direct thalamic inputs into a cortical representation which acquires new spatio-temporal properties. One of these properties, motion selectivity, has not been strongly tied to putative neural mechanisms, and its origins remain poorly understood. Here we propose that motion selectivity is acquired through the recurrent mechanisms of a network of strongly connected neurons. We first show that a bank of V1 spatiotemporal receptive fields can be generated accurately by a network which receives only instantaneous inputs from the retina. The temporal structure of the receptive fields is generated by the long timescale dynamics associated with the high magnitude eigenvalues of the recurrent connectivity matrix. When these eigenvalues have complex parts, they generate receptive fields that are inseparable in time and space, such as those tuned to motion direction. We also show that the recurrent connectivity patterns can be learnt directly from the statistics of natural movies using a temporally-asymmetric Hebbian learning rule. Probed with drifting grating stimuli and moving bars, neurons in the model show patterns of responses analogous to those of direction-selective simple cells in primary visual cortex. These computations are enabled by a specific pattern of recurrent connections, that can be tested by combining connectome reconstructions with functional recordings.*Author summaryDynamic visual scenes provide our eyes with enormous quantities of visual information, particularly when the visual scene changes rapidly. Even at modest moving speeds, individual small objects quickly change their location causing single points in the scene to change their luminance equally fast. Furthermore, our own movements through the world add to the velocities of objects relative to our retinas, further increasing the speed at which visual inputs change. How can a biological system process efficiently such vast amounts of information, while keeping track of objects in the scene? Here we formulate and analyze a solution that is enabled by the temporal dynamics of networks of neurons.

scholarly journals A Circuit for Integration of Head- and Visual-Motion Signals in Layer 6 of Mouse Primary Visual Cortex

Neuron ◽  
2018 ◽  
Vol 98 (1) ◽  
pp. 179-191.e6 ◽  
Author(s):  
Mateo Vélez-Fort ◽  
Edward F. Bracey ◽  
Sepiedeh Keshavarzi ◽  
Charly V. Rousseau ◽  
Lee Cossell ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Motion

scholarly journals Downregulation of early visual cortex excitability mediates oscillopsia suppression

Neurology ◽  
2017 ◽  
Vol 89 (11) ◽  
pp. 1179-1185 ◽  
Author(s):  
Hena Ahmad ◽  
R. Edward Roberts ◽  
Mitesh Patel ◽  
Rhannon Lobo ◽  
Barry Seemungal ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Motion ◽  
Cortical Excitability ◽  
Critical Role ◽  
Adaptive Mechanism ◽  
Motion Adaptation ◽  
Adaptive Mechanisms ◽  
Symptom Load ◽  
Early Visual Cortex ◽  
Adaptation Condition

Objective:To identify in an observational study the neurophysiologic mechanisms that mediate adaptation to oscillopsia in patients with bilateral vestibular failure (BVF).Methods:We directly probe the hypothesis that adaptive changes that mediate oscillopsia suppression implicate the early visual-cortex (V1/V2). Accordingly, we investigated V1/V2 excitability using transcranial magnetic stimulation (TMS) in 12 avestibular patients and 12 healthy controls. Specifically, we assessed TMS-induced phosphene thresholds at baseline and cortical excitability changes while performing a visual motion adaptation paradigm during the following conditions: baseline measures (i.e., static), during visual motion (i.e., motion before adaptation), and during visual motion after 5 minutes of unidirectional visual motion adaptation (i.e., motion adapted).Results:Patients had significantly higher baseline phosphene thresholds, reflecting an underlying adaptive mechanism. Individual thresholds were correlated with oscillopsia symptom load. During the visual motion adaptation condition, no differences in excitability at baseline were observed, but during both the motion before adaptation and motion adapted conditions, we observed significantly attenuated cortical excitability in patients. Again, this attenuation in excitability was stronger in less symptomatic patients.Conclusions:Our findings provide neurophysiologic evidence that cortically mediated adaptive mechanisms in V1/V2 play a critical role in suppressing oscillopsia in patients with BVF.

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