Encoding of binocular disparity by complex cells in the cat's visual cortex

Area of Science:

• Neuroscience
• Computational Vision
• Sensory Systems

Background:

• Stereopsis, the perception of depth from binocular vision, relies on processing visual information from both eyes.
• Complex cells in the striate cortex are known to respond to visual stimuli but their specific role in stereopsis requires further elucidation.

Purpose of the Study:

• To investigate the function of complex cells in stereopsis by analyzing their binocular response properties.
• To determine the selectivity of complex cells for binocular disparity and stimulus position.

Main Methods:

• Extracellular recordings from single neurons in the striate cortex of anesthetized cats.
• Measurement of binocular responses using a comprehensive stimulus set varying positions and contrasts for both eyes.
• Characterization of binocular receptive field (RF) profiles.

Main Results:

• Complex cells exhibit strong binocular disparity selectivity, with selectivity for disparity being significantly narrower than for position.
• Binocular RFs are largely consistent for stimuli of the same contrast sign but inverted for opposite contrast signs.
• A disparity energy model successfully accounts for most complex cell behaviors, though some deviations were observed.

Conclusions:

• Complex cells provide a higher level of abstraction for stereopsis by integrating inputs from simple-type subunits.
• Their narrow disparity tuning and position invariance contribute to solving the stereo correspondence problem in complex scenes.
• These cells significantly reduce the complexity of depth perception processing.