Contextual modulation of sensitivity to naturalistic image structure in macaque V2

Area of Science:

• Neuroscience
• Computational Neuroscience
• Visual Perception

Background:

• Neuronal responses in the primary visual cortex (V1) are selective but influenced by extra-classical receptive field input.
• Understanding how selectivity is modified in later visual areas like V2 is less understood.
• V2 neurons may represent higher-order statistical dependencies in natural images.

Purpose of the Study:

• To investigate the role of stimulus size in V2 neuronal responses to naturalistic versus noise images.
• To explore the influence of the receptive field surround on V2 selectivity for natural textures.
• To elucidate the mechanisms underlying V2's enhanced sensitivity to complex visual structures.

Main Methods:

• Recording neuronal activity in V2 and V1.
• Presenting naturalistic and noise stimuli of varying sizes.
• Analyzing stimulus-evoked responses and surround modulation.
• Examining response latency and time course.

Main Results:

• V2 neurons showed a modest preference for naturalistic over noise stimuli at small sizes, which strengthened with increasing size.
• Surround suppression was more pronounced for noise stimuli than for naturalistic stimuli.
• The preference for large naturalistic stimuli developed with a delayed time course, suggesting lateral or feedback connections.

Conclusions:

• V2 neurons exhibit a size-dependent preference for naturalistic stimuli, mediated by mechanisms extending beyond the classical receptive field.
• The receptive field surround in V2 plays a distinct role in processing complex image statistics, unlike in V1.
• These findings suggest a spatially broad facilitatory mechanism in V2 contributes to sensitivity for natural visual textures.