Norm-based coding of faces in the anterior fundus face patch

Authors

• AP Jones
• DB McMahon
• BE Russ
• DA Leopold

Abstract

Face perception, a fundamental component of primate social behavior, is supported by a network of specialized visual regions recently identified within the ventral visual stream of humans and macaques. Discrete regions, or “patches” within this network respond preferentially to face images over non-face object images, with the majority of visually responsive neurons within these regions firing selectively to faces. In this study, we have investigated the selectivity of neurons in one such patch (AF) located in the anterior fundus of the superior temporal sulcus. Using sets of morphed monkey faces and morphed human faces, we found that a large population of neurons responded to the distinctiveness of briefly presented faces, with the average face yielding the smallest response over the majority of the population. The finding was present for both human and monkey faces, though monkey faces generally gave larger responses across the population. Such norm-based tuning closely resembles previous results in ventral IT cortex (TEav, Leopold et al 2006) and is in accord with psychophysical models for face perception holding a special role of the average face for extracting individual identity. The use of longitudinal electrophysiological recording, allowing us to monitor individual neurons for weeks at a time, provided us with sensitivity to the potential contribution of within- and between- sessions to the effects of adaption, for which no evidence was found during the entire 75 days of recording. These results contribute an emerging understanding of functional compartmentalization in macaque face-processing system.

Scientific Focus Area: Neuroscience

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