Equivalent representation of real and illusory contours in macaque V4

Area of Science:

• Neuroscience
• Visual Perception
• Computational Neuroscience

Background:

• Illusory contours offer insights into visual perception mechanisms.
• Previous studies show V1 and V2 cells signal illusory contours, while human imaging highlights higher visual cortices.
• Processing illusory contours likely involves hierarchical interactions in the ventral visual pathway.

Purpose of the Study:

• To determine where illusory contours are represented similarly to real contours at population and single-cell levels.
• To investigate the neural basis of contour integration in the primate visual system.

Main Methods:

• Combined intrinsic optical imaging in anesthetized macaques with single-cell recordings in awake macaques.
• Mapped orientation domains for real and illusory contours in visual cortical areas V1, V2, and V4.

Main Results:

• Visual cortical area V4 showed a complete overlap in orientation domains for real and illusory contours.
• Early visual areas V1 and V2 primarily encoded local stimulus features that induce illusory contours.
• Real and illusory contours are encoded equivalently by the same functional domains in V4.

Conclusions:

• Visual cortical area V4 acts as a key locus for integrating local features into global contours.
• V4 represents real and illusory contours in an equivalent manner, suggesting a unified contour processing mechanism.
• Findings advance understanding of how the brain constructs complete visual percepts from fragmented information.