Recognition of objects and their component parts: responses of single units in the temporal cortex of the macaque.

We investigated the role that different component parts play in the neural encoding of the visual appearance of one complex object in the temporal cortex. Cells responsive to the sight of the entire human body (but no to control stimuli) were tested with two subregions (head alone with the body occluded from sight and the body alone with the head occluded). Forty-two percent (22 of 53) of cells responded to the whole body and to one of the two body regions tested separately: 72% (17 of 22) responding to the head and 28% (5 of 22) to the rest of the body. Forty-two percent (22 of 53) of cells responded independently to both regions of the body when tested in isolation. The remaining cells (17%, 9 of 53) were selective for the entire body and unresponsive to component parts. The majority of cells tested (90%, 35 of 39) were selective for perspective view (e.g., some cells respond optimally to the side view of the body, others to the back view). Comparable levels of view sensitivity were found for responses to the whole body and its parts. Results indicate (1) separate neuronal analysis of body parts and (2) extensive integration of information from different parts. Contrary to influential models of object recognition (Marr and Nishihara, 1978; Biederman, 1987), the results indicate view-specific processing both for the appearance of separate object components and for integration of information across components.