Perceptual training continuously refines neuronal population codes in primary visual cortex

2014 ◽  
Vol 17 (10) ◽  
pp. 1380-1387 ◽  
Author(s):  
Yin Yan ◽  
Malte J Rasch ◽  
Minggui Chen ◽  
Xiaoping Xiang ◽  
Min Huang ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Neuronal Population ◽  
Perceptual Training ◽  
Population Codes

Equalization and decorrelation in primary visual cortex

2014 ◽  
Vol 112 (3) ◽  
pp. 501-503 ◽  
Author(s):  
Koen V. Haak ◽  
Elizabeth Fast ◽  
Yihwa Baek ◽  
Juraj Mesik
Keyword(s):  
Visual Cortex ◽  
Recent Work ◽  
Primary Visual Cortex ◽  
Neuronal Population ◽  
Neural Adaptation ◽  
First Time

There are many theories on the purpose of neural adaptation, but evidence remains elusive. Here, we discuss the recent work by Benucci et al. ( Nat Neurosci 16: 724–729, 2013), who measured for the first time the immediate effects of adaptation on the overall activity of a neuronal population. These measurements confirm two long-standing hypotheses about the purpose of adaptation, namely that adaptation counteracts biases in the statistics of the environment, and that it maintains decorrelation in neuronal stimulus selectivity.

scholarly journals Neuronal population mechanisms of lightness perception

2018 ◽  
Vol 120 (5) ◽  
pp. 2296-2310 ◽  
Author(s):  
Douglas A. Ruff ◽  
David H. Brainard ◽  
Marlene R. Cohen
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Neuronal Population ◽  
Neuronal Responses ◽  
Lightness Perception ◽  
Neuronal Mechanism ◽  
Area V4 ◽  
Neuronal Populations ◽  
Types Of Information ◽  
The Way

The way that humans and animals perceive the lightness of an object depends on its physical luminance as well as its surrounding context. While neuronal responses throughout the visual pathway are modulated by context, the relationship between neuronal responses and lightness perception is poorly understood. We searched for a neuronal mechanism of lightness by recording responses of neuronal populations in monkey primary visual cortex (V1) and area V4 to stimuli that produce a lightness illusion in humans, in which the lightness of a disk depends on the context in which it is embedded. We found that the way individual units encode the luminance (or equivalently for our stimuli, contrast) of the disk and its context is extremely heterogeneous. This motivated us to ask whether the population representation in either V1 or V4 satisfies three criteria: 1) disk luminance is represented with high fidelity, 2) the context surrounding the disk is also represented, and 3) the representations of disk luminance and context interact to create a representation of lightness that depends on these factors in a manner consistent with human psychophysical judgments of disk lightness. We found that populations of units in both V1 and V4 fulfill the first two criteria but that we cannot conclude that the two types of information in either area interact in a manner that clearly predicts human psychophysical measurements: the interpretation of our population measurements depends on how subsequent areas read out lightness from the population responses. NEW & NOTEWORTHY A core question in visual neuroscience is how the brain extracts stable representations of object properties from the retinal image. We searched for a neuronal mechanism of lightness perception by determining whether the responses of neuronal populations in primary visual cortex and area V4 could account for a lightness illusion measured using human psychophysics. Our results suggest that comparing psychophysics with population recordings will yield insight into neuronal mechanisms underlying a variety of perceptual phenomena.

scholarly journals fMRI Reveals a Common Neural Substrate of Illusory and Real Contours in V1 after Perceptual Learning

2005 ◽  
Vol 17 (10) ◽  
pp. 1553-1564 ◽  
Author(s):  
Marianne Maertens ◽  
Stefan Pollmann
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Perceptual Learning ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Learning Effects ◽  
Illusory Contours ◽  
Perceptual Training ◽  
Induced Changes ◽  
Field Position

Perceptual learning involves the specific and relatively permanent modification of perception following a sensory experience. In psychophysical experiments, the specificity of the learning effects to the trained stimulus attributes (e.g., visual field position or stimulus orientation) is often attributed to assumed neural modifications at an early cortical site within the visual processing hierarchy. We directly investigated a neural correlate of perceptual learning in the primary visual cortex using fMRI. Twenty volunteers practiced a curvature discrimination on Kanizsa-type illusory contours in the MR scanner. Practice-induced changes in the BOLD response to illusory contours were compared between the pretraining and the posttraining block in those areas of the primary visual cortex (V1) that, in the same session, had been identified to represent real contours at corresponding visual field locations. A retinotopically specific BOLD signal increase to illusory contours was observed as a consequence of the training, possibly signaling the formation of a contour representation, which is necessary for performing the curvature discrimination. The effects of perceptual training were maintained over a period of about 10 months, and they were specific to the trained visual field position. The behavioral specificity of the learning effects supports an involvement of V1 in perceptual learning, and not in unspecific attentional effects.

scholarly journals Neuronal population mechanisms of lightness perception

2018 ◽  
Author(s):  
Douglas A. Ruff ◽  
David H. Brainard ◽  
Marlene R. Cohen
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Neuronal Population ◽  
Neuronal Responses ◽  
Lightness Perception ◽  
Neuronal Mechanism ◽  
Area V4 ◽  
Neuronal Populations ◽  
Types Of Information ◽  
The Way

AbstractThe way that humans and animals perceive the lightness of an object depends on its physical luminance as well as its surrounding context. While neuronal responses throughout the visual pathway are modulated by context, the relationship between neuronal responses and lightness perception is poorly understood. We searched for a neuronal mechanism of lightness by recording responses of neuronal populations in monkey primary visual cortex (V1) and area V4 to stimuli that produce a lightness illusion in humans, in which the lightness of a disk depends on the context in which it is embedded. We found that the way individual units encode the luminance (or equivalently for our stimuli, contrast) of the disk and its context is extremely heterogeneous. This motivated us to ask whether the population representation in either V1 or V4 satisfies three criteria: 1) disk luminance is represented with high fidelity, 2) the context surrounding the disk is also represented, and 3) the representations of disk luminance and context interact to create a representation of lightness that depends on these factors in a manner consistent with human psychophysical judgments of disk lightness. We found that populations of units in both V1 and V4 fulfill the first two criteria, but that we cannot conclude that the two types of information in either area interact in a manner that clearly predicts human psychophysical measurements: the interpretation of our population measurements depends on how subsequent areas read out lightness from the population responses.New & NoteworthyA core question in visual neuroscience is how the brain extracts stable representations of object properties from the retinal image. We searched for a neuronal mechanism of lightness perception by determining whether the responses of neuronal populations in primary visual cortex and area V4 could account for a lightness illusion measured using human psychophysics. Our results suggest that comparing psychophysics with population recordings will yield insight into neuronal mechanisms underlying a variety of perceptual phenomena.

scholarly journals Spatiotemporal dynamics of neuronal population response in the primary visual cortex

2013 ◽  
Vol 110 (23) ◽  
pp. 9517-9522 ◽  
Author(s):  
Douglas Zhou ◽  
Aaditya V. Rangan ◽  
David W. McLaughlin ◽  
David Cai
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Neuronal Population ◽  
Spatiotemporal Dynamics ◽  
Population Response

scholarly journals Binocular Integration Manifests as a Transient Spiking Increase Followed by Selective Suppression in Primary Visual Cortex

2018 ◽  
Author(s):  
Michele A. Cox ◽  
Kacie Dougherty ◽  
Jacob A. Westerberg ◽  
Michelle S. Schall ◽  
Alexander Maier
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Information ◽  
Temporal Dynamics ◽  
Neuronal Population ◽  
Stimulus Onset ◽  
Monocular Stimulation ◽  
Binocular Stimulation ◽  
Behaving Monkeys ◽  
Open Question

AbstractResearch throughout the past decades revealed that neurons in primate primary visual cortex (V1) rapidly integrate the two eyes’ separate signals into a combined binocular response. The exact mechanisms giving underlying this binocular integration remain elusive. One open question is whether binocular integration occurs at a single stage of sensory processing or in a sequence of computational steps. To address this question, we examined the temporal dynamics of binocular integration across V1’s laminar microcircuit of awake behaving monkeys. We find that V1 processes binocular stimuli in a dynamic sequence that comprises at least two distinct phases: A transient phase, lasting 50-150ms from stimulus onset, in which neuronal population responses are significantly enhanced for binocular stimulation compared to monocular stimulation, followed by a sustained phase characterized by widespread suppression in which feature-specific computations emerge. In the sustained phase, incongruent binocular stimulation resulted in response reduction relative to monocular stimulation across the V1 population. By contrast, sustained responses for binocular congruent stimulation were either reduced or enhanced relative to monocular responses depending on the neurons’ selectivity for one or both eyes (i.e., ocularity). These results suggest that binocular integration in V1 occurs in at least two sequential steps, with an initial additive combination of the two eyes’ signals followed by the establishment of interocular concordance and discordance.Significance StatementOur two eyes provide two separate streams of visual information that are merged in the primary visual cortex (V1). Previous work showed that stimulating both eyes rather than one eye may either increase or decrease activity in V1, depending on the nature of the stimuli. Here we show that V1 binocular responses change over time, with an early phase of general excitation and followed by stimulus-dependent response suppression. These results provide important new insights into the neural machinery that supports the combination of the two eye’s perspectives into a single coherent view.

scholarly journals Pure tones modulate the representation of orientation and direction in the primary visual cortex

2019 ◽  
Author(s):  
John P McClure ◽  
Pierre-Olivier Polack
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Stimulus ◽  
Population Level ◽  
Brain Regions ◽  
Neuronal Population ◽  
Direction Selectivity ◽  
Multimodal Integration ◽  
Multisensory Interactions ◽  
Sensory Cortices

Multimodal sensory integration facilitates the generation of a unified and coherent perception of the environment. It is now well established that unimodal sensory perceptions, such as vision, are improved in multisensory contexts. While multimodal integration is primarily performed by dedicated multisensory brain regions such as the association cortices or the superior colliculus, recent studies have shown that multisensory interactions also occur in primary sensory cortices. In particular, sounds were shown to modulate the responses of neurons located in layers 2/3 (L2/3) of the mouse primary visual cortex (V1). Yet, the net effect of sound modulation at the V1 population level remained unclear. Here, we performed two-photon calcium imaging in awake mice to compare the representation of the orientation and the direction of drifting gratings by V1 L2/3 neurons in unimodal (visual only) or multi-modal (audiovisual) conditions. We found that sound modulation depended on the tuning properties (orientation and direction selectivity) and response amplitudes of V1 L2/3 neurons. Sounds potentiated the responses of neurons that were highly tuned to the cue orientation and direction but weakly active in the unimodal context, following the principle of inverse effectiveness of multimodal integration. Moreover, sound suppressed the responses of neurons untuned for the orientation and/or the direction of the visual cue. Altogether, sound modulation improved the representation of the orientation and direction of the visual stimulus in V1 L2/3. Namely, visual stimuli presented with auditory stimuli recruited a neuronal population better tuned to the visual stimulus orientation and direction than when presented alone.

scholarly journals Population Codes Enable Learning from Few Examples By Shaping Inductive Bias

2021 ◽  
Author(s):  
Blake Bordelon ◽  
Cengiz Pehlevan
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Small Sample ◽  
Learning Performance ◽  
Neural Responses ◽  
Population Code ◽  
Inductive Bias ◽  
Stimulus Response ◽  
Population Codes ◽  
Efficient Learning

The brain can learn from a limited number of experiences, an ability which requires suitable built in assumptions about the nature of the tasks which must be learned, or inductive biases. While inductive biases are central components of intelligence, how they are reflected in and shaped by population codes are not well-understood. To address this question, we consider biologically-plausible reading out of an arbitrary stimulus-response pattern from an arbitrary population code, and develop an analytical theory that predicts the generalization error of the readout as a function of the number of samples. We find that learning performance is controlled by the eigenspectrum of the population code's inner-product kernel, which measures the similarity of neural responses to two different input stimuli. Many different codes can realize the same kernel; by analyzing recordings from the mouse primary visual cortex, we demonstrate that biological codes are metabolically more efficient than other codes with identical kernels. We demonstrate that the spectral properties of the kernel introduce an inductive bias toward explaining stimulus-response samples with simple functions and determine compatibility of the population code with learning task, and hence the sample-efficiency of learning. While the tail of the spectrum is important for large sample size behavior of learning, for small sample sizes, the bulk of the spectrum governs generalization. We apply our theory to experimental recordings of mouse primary visual cortex neural responses, elucidating a bias towards sample-efficient learning of low frequency orientation discrimination tasks. We demonstrate this emergence of this bias in a simple model of primary visual cortex, and further show how invariances in the code to stimulus variations affect learning performance. Finally, we demonstrate that our methods are applicable to time-dependent neural codes. Overall, our study suggests sample-efficient learning as a general normative coding principle.

Phosphene perceptions and safety of chronic visual cortex stimulation in a blind subject

2020 ◽  
Vol 132 (6) ◽  
pp. 2000-2007 ◽  
Author(s):  
Soroush Niketeghad ◽  
Abirami Muralidharan ◽  
Uday Patel ◽  
Jessy D. Dorn ◽  
Laura Bonelli ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Adverse Events ◽  
Clinical Intervention ◽  
Occipital Cortex ◽  
Neuronal Population ◽  
Serious Adverse Events ◽  
Stimulation Parameters ◽  
The Right ◽  
Visual Cortical ◽  
Stimulation Of

Stimulation of primary visual cortices has the potential to restore some degree of vision to blind individuals. Developing safe and reliable visual cortical prostheses requires assessment of the long-term stability, feasibility, and safety of generating stimulation-evoked perceptions.A NeuroPace responsive neurostimulation system was implanted in a blind individual with an 8-year history of bare light perception, and stimulation-evoked phosphenes were evaluated over 19 months (41 test sessions). Electrical stimulation was delivered via two four-contact subdural electrode strips implanted over the right medial occipital cortex. Current and charge thresholds for eliciting visual perception (phosphenes) were measured, as were the shape, size, location, and intensity of the phosphenes. Adverse events were also assessed.Stimulation of all contacts resulted in phosphene perception. Phosphenes appeared completely or partially in the left hemifield. Stimulation of the electrodes below the calcarine sulcus elicited phosphenes in the superior hemifield and vice versa. Changing the stimulation parameters of frequency, pulse width, and burst duration affected current thresholds for eliciting phosphenes, and increasing the amplitude or frequency of stimulation resulted in brighter perceptions. While stimulation thresholds decreased between an average of 5% and 12% after 19 months, spatial mapping of phosphenes remained consistent over time. Although no serious adverse events were observed, the subject experienced mild headaches and dizziness in three instances, symptoms that did not persist for more than a few hours and for which no clinical intervention was required.Using an off-the-shelf neurostimulator, the authors were able to reliably generate phosphenes in different areas of the visual field over 19 months with no serious adverse events, providing preliminary proof of feasibility and safety to proceed with visual epicortical prosthetic clinical trials. Moreover, they systematically explored the relationship between stimulation parameters and phosphene thresholds and discovered the direct relation of perception thresholds based on primary visual cortex (V1) neuronal population excitation thresholds.

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