Binocular interaction and disparity coding in area 19 of visual cortex in normal and split-chiasm cats

Area of Science:

• Neuroscience
• Visual Perception
• Computational Neuroscience

Background:

• Binocular disparity is a key cue for stereoscopic depth perception.
• Cellular binocularity arises from retinal inputs and interhemispheric connections via the corpus callosum (CC).
• Previous research established disparity-sensitive cells in earlier visual areas (17-18).

Purpose of the Study:

• To investigate the presence and properties of disparity-sensitive cells in the higher-order visual area 19 of the cat.
• To determine the contribution of the corpus callosum (CC) to the formation of these disparity-sensitive cells.

Main Methods:

• Electrophysiological recordings were performed in area 19 of normal and split-chiasm cats.
• Neurons were classified based on their responses to stimuli presented with varying binocular disparities.
• Results were compared with existing data from areas 17-18 and behavioral studies.

Main Results:

• Two types of disparity-sensitive neurons were identified in area 19, similar to areas 17-18, signaling different depth planes.
• Area 19 contained fewer disparity-sensitive cells than areas 17-18, and these cells were less finely tuned.
• In split-chiasm cats, very few disparity-sensitive cells were found, indicating a limited role for the CC.

Conclusions:

• Area 19 appears less involved in disparity analysis than area 17.
• Disparity-sensitive neurons in area 19 are not primarily involved in resolving fine stereoscopic detail.
• The corpus callosum contributes to a limited number of disparity-sensitive cells when normal binocular input is absent.