Inferior Temporal Cortex: Where Visual Perception Meets Memory

Abstract

The neural processes that lead to visual perception and memory, thus subserving the identification of objects, have been assigned to the multi­ synaptic occipito-temporo-limbic projection that interconnects the striate, prestriate, inferior temporal, and hippocampal cortices (Gross 1972; Maunsell & Newsome 1987; Mishkin et al 1983). Recent advances in our understanding of the organization of the extra striate cortex revealed a mosaic of more than 25 visual areas beyond the striate cortex (Felleman & Van Essen 1991; Van Essen 1985; Zeki & Shipp 1988). The physical properties of a visuaJ object (such as its size, color, texture, and shape) are analyzed in the multiple subdivisions of the prestriate-posterior temporal complex. The anterior part of inferior temporal cortex has been hypo­ thesized not only to synthesize the analyzed attributes into a unique con­ figuration, but also to work as the storehouse for central representations of the objects (Mishkin 1982; Weiskrantz & Saunders 1984). The supporting evidence for this hypothesis has mainly been given by neuropsychological approaches (Milner 1990; Squire & Zola-Morgan 1991; Weiskrantz 1990). Recently, neuronal correlates of the visual long-term memory were found: The temporal-lobe neurons could reflect learned associative relations among stimuli (Miyashita 1988; Sakai & Miyashita 1991). The findings on this associational mechanism, together with that on the feature selectivity