Contextual effects on binocular matching are evident in primary visual cortex

Binocular matching of orientation preference between the two eyes is a common form of binocular integration that is regarded as the basis for stereopsis. How critical period plasticity enables binocular matching under the guidance of normal visual experience has not been fully demonstrated. To investigate how critical period closure affects the binocular matching, a critical period prolonged mouse model was constructed through the administration of bumetanide, an NKCC1 transporter antagonist. Using acute in vivo extracellular recording and molecular assay, we revealed that binocular matching was transiently disrupted due to heightened plasticity after the normal critical period, together with an increase in the density of spines and synapses, and the upregulation of GluA1 expression. Diazepam (DZ)/[(R, S)-3-(2-carboxypiperazin-4-yl) propyl-1-phosphonic acid (CPP)] could reclose the extended critical period, and rescue the deficits in binocular matching. Furthermore, the extended critical period, alone, with normal visual experience is sufficient for the completion of binocular matching in amblyopic mice. Similarly, prolonging the critical period into adulthood by knocking out Nogo-66 receptor can prevent the normal maturation of binocular matching and depth perception. These results suggest that maintaining an optimal plasticity level during adolescence is most beneficial for the systemic maturation. Extending the critical period provides new clues for the maturation of binocular vision and may have critical implications for the treatment of amblyopia.

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Constrained inference in sparse coding reproduces contextual effects and predicts laminar neural dynamics

10.1101/555128 ◽

2019 ◽

Cited By ~ 3

Author(s):

Federica Capparelli ◽

Klaus Pawelzik ◽

Udo Ernst

Keyword(s):

Visual Cortex ◽

Receptive Field ◽

Primary Visual Cortex ◽

Sparse Coding ◽

Contextual Effects ◽

Direct Access ◽

Contextual Processing ◽

Classical Receptive Field ◽

Non Linear ◽

Visual Scenes

AbstractA central goal in visual neuroscience is to understand computational mechanisms and to identify neural structures responsible for integrating local visual features into global representations. When probed with complex stimuli that extend beyond their classical receptive field, neurons display non-linear behaviours indicative of such integration processes already in early stages of visual processing. Recently some progress has been made in explaining these effects from first principles by sparse coding models with a neurophysiologically realistic inference dynamics. They reproduce some of the complex response characteristics observed in primary visual cortex, but only when the context is located near the classical receptive field, since the connection scheme they propose include interactions only among neurons with overlapping input fields. Longer-range interactions required for addressing the plethora of contextual effects reaching beyond this range do not exist. Hence, a satisfactory explanation of contextual phenomena in terms of realistic interactions and dynamics in visual cortex is still missing. Here we propose an extended generative model for visual scenes that includes spatial dependencies among different features. We derive a neurophysiologically realistic inference scheme under the constraint that neurons have direct access to only local image information. The scheme can be interpreted as a network in primary visual cortex where two neural populations are organized in different layers within orientation hypercolumns that are connected by local, short-range and long-range recurrent interactions. When trained with natural images, the model predicts a connectivity structure linking neurons with similar orientation preferences matching the typical patterns found for long-ranging horizontal axons and feedback projections in visual cortex. Subjected to contextual stimuli typically used in empirical studies our model replicates several hallmark effects of contextual processing and predicts characteristic differences for surround modulation between the two model populations. In summary, our model provides a novel framework for contextual processing in the visual system proposing a well-defined functional role for horizontal axons and feedback projections.Author summaryAn influential hypothesis about how the brain processes visual information posits that each given stimulus should be efficiently encoded using only a small number of cells. This idea led to the development of a class of models that provided a functional explanation for various response properties of visual neurons, including the non-linear modulations observed when localized stimuli are placed in a broader spatial context. However, it remains to be clarified through which anatomical structures and neural connectivities a network in the cortex could perform the computations that these models require. In this paper we propose a model for encoding spatially extended visual scenes. Imposing the constraint that neurons in visual cortex have direct access only to small portions of the visual field we derive a simple yet realistic neural population dynamics. Connectivities optimized for natural scenes conform with anatomical findings and the resulting model reproduces a broad set of physiological observations, while exposing the neural mechanisms relevant for spatio-temporal information integration.

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A mean-field model for orientation tuning, contrast saturation, and contextual effects in the primary visual cortex

Biological Cybernetics ◽

10.1007/s004220050583 ◽

2000 ◽

Vol 82 (4) ◽

pp. 291-304 ◽

Cited By ~ 14

Author(s):

Martin Stetter ◽

Hauke Bartsch ◽

Klaus Obermayer

Keyword(s):

Visual Cortex ◽

Primary Visual Cortex ◽

Field Model ◽

Mean Field ◽

Contextual Effects ◽

Orientation Tuning ◽

Mean Field Model

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Contextual effects on binocular matching are evident in primary visual cortex

10.1101/541466 ◽

2019 ◽

Author(s):

Reuben Rideaux ◽

Andrew E Welchman

Keyword(s):

Visual Cortex ◽

Visual Perception ◽

Neural Activity ◽

Pattern Analysis ◽

Brain Activity ◽

Contextual Effects ◽

Local Processing ◽

Neuronal Responses ◽

Global Context ◽

Binocular Matching

ABSTRACTGlobal context can dramatically influence local visual perception. This phenomenon is well-documented for monocular features, e.g., the Kanizsa triangle. It has been demonstrated for binocular matching: the disambiguation of the Wallpaper Illusion (Brewster, 1844) via the luminance of the background (Anderson & Nakayama, 1994). For monocular features, there is evidence that global context can influence neuronal responses as early as V1 (Muckli et al., 2015). However, for binocular matching, the activity in this area of the visual cortex is thought to represent local processing, suggesting that the influence of global context may occur at later stages of cortical processing. Here we sought to test if binocular matching is influenced by contextual effects in V1, using fMRI to measure brain activity while participants viewed perceptually ambiguous “wallpaper” stereograms whose depth was disambiguated by the luminance of the surrounding region. We localized voxels in V1 corresponding to the ambiguous region of the pattern, i.e., where the signal received from the eyes was not predictive of depth, and despite the ambiguity of the input signal, using multi-voxel pattern analysis we were able to reliably decode perceived (near/far) depth from the activity of these voxels. These findings indicate that stereoscopic related neural activity is influenced by global context as early as V1.

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