Disparity selectivity of neurons in monkey inferior temporal cortex

Area of Science:

• Neuroscience
• Visual Perception
• Computational Neuroscience

Background:

• The inferior temporal cortex (IT) is a key area in the ventral visual pathway, traditionally associated with processing 2-D visual features like shape, color, and texture.
• The dorsal visual pathway, leading to the posterior parietal cortex, is primarily known for processing spatial information, including location and depth cues like binocular disparity.

Purpose of the Study:

• To investigate whether neurons in the inferior temporal cortex (IT) exhibit selectivity for binocular disparity, a cue for depth perception.
• To determine if disparity selectivity in the IT is linked to other visual features like shape and its invariance to stimulus transformations.

Main Methods:

• Extracellular recordings of neuronal activity in the IT of monkeys.
• Presentation of visual stimuli with varying binocular disparity to assess neuronal responses.
• Analysis of neuronal selectivity for disparity, shape, and invariance to stimulus translation.

Main Results:

• Over half of the recorded IT neurons showed altered responses based on the presented binocular disparity.
• The majority of disparity-selective neurons were classified as 'near' or 'far' cells, preferring crossed or uncrossed disparities, respectively.
• Disparity selectivity was often shape-dependent, with preferences remaining consistent across different shapes and fronto-parallel translations for most neurons.

Conclusions:

• The inferior temporal cortex (IT) possesses neurons selective for binocular disparity, challenging the traditional view of its functional specialization.
• The IT appears to integrate visual information regarding shape and binocular disparity, contributing to the neural basis of three-dimensional (3-D) surface perception.