The neural code for 'face cells' is not face specific

Abstract

1 Face cells are visual neurons that respond more to faces than other objects. Clustered together in inferotemporal cortex, they are thought to carry out face processing specifically and are thus studied using faces almost exclusively. Analyzing neural responses in and around macaque face patches to hundreds of objects, we found graded response profiles for non-faces that were predictive of the degree of face selectivity and provided information on face-cell tuning that could not be characterized with actual faces. This relationship between non-face and face responses was not predicted by color and simple shape properties, but by information encoded in deep neural networks trained on general object classification rather than face identification. These findings contradict the long-standing assumption that face cells owe their category selectivity to face-specific features, instead providing evidence for the notion that category-selective neurons are best understood as tuning directions in an integrated, domain-general object space.