Functional Compartmentalization and Viewpoint Generalization Within the Macaque Face-Processing System

TLDR

Primates recognize faces across varied viewing conditions, implying the need for identity representations invariant to transformations such as view direction. The study recorded neuronal activity from the six face-selective patches of the macaque face-processing network, focusing on the middle patches ML and MF and the anterior patches AL and AM. ML and MF neurons were view-specific, AL neurons encoded identity mirror-symmetrically across views for partial invariance, and AM neurons achieved near full view invariance, showing that face patch position determines identity representation across head orientations.

Abstract

Primates can recognize faces across a range of viewing conditions. Representations of individual identity should thus exist that are invariant to accidental image transformations like view direction. We targeted the recently discovered face-processing network of the macaque monkey that consists of six interconnected face-selective regions and recorded from the two middle patches (ML, middle lateral, and MF, middle fundus) and two anterior patches (AL, anterior lateral, and AM, anterior medial). We found that the anatomical position of a face patch was associated with a unique functional identity: Face patches differed qualitatively in how they represented identity across head orientations. Neurons in ML and MF were view-specific; neurons in AL were tuned to identity mirror-symmetrically across views, thus achieving partial view invariance; and neurons in AM, the most anterior face patch, achieved almost full view invariance.