Disparity selectivity of neurons in monkey inferior temporal cortex

The inferior temporal cortex (IT) of the monkey, a final stage in the ventr al visual pathway, has been known to process information on two-dimensional (2-D) shape, color, and texture. On the other hand, the dorsal visual path way leading to the posterior parietal cortex has been known to process info rmation on location in space. Likewise, neurons selective for binocular dis parity, which convey information on depth, have been found mainly in areas along the dorsal visual pathway. Here, we report that many neurons in the I T are also selective for binocular disparity. We recorded extracellular act ivity from IT neurons and found that more than half of the neurons changed their response depending on the disparity added. The change was not attribu ted to monocular responses or eye movements. Most neurons selective for dis parity were "near" or "far" cells; they preferred either crossed or uncross ed disparity, and only a small population was tuned to zero disparity. Disp arity-selective neurons were also selective for shape. Most preferred the s ame type of disparity irrespective of the shape presented. Disparity prefer ence was also invariant for the fronto-parallel translation of the stimuli in most of the neurons. Finally, nearby neurons exhibited similar disparity selectivity, suggesting the existence of a functional module for processin g of binocular disparity in the IT. From the above and our recent findings, we suggest that the IT integrates shape and binocular disparity informatio n, and plays an important role in the reconstruction of three-dimensional ( 3-D) surfaces.