[Neural representations of facial identity and its associative meaning]

Since the discovery of "face cells" in the early 1980s, single-cell recording experiments in non-human primates have made significant contributions toward the elucidation of neural mechanisms underlying face perception and recognition. In this paper, we review the recent progress in face cell studies, including the recent remarkable findings of the face patches that are scattered around the anterior temporal cortical areas of monkeys. In particular, we focus on the neural representations of facial identity within these areas. The identification of faces requires both discrimination of facial identities and generalization across facial views. It has been indicated by some laboratories that the population of face cells found in the anterior ventral inferior temporal cortex of monkeys represent facial identity in a manner which is facial view-invariant. These findings suggest a relatively distributed representation that operates for facial identification. It has also been shown that certain individual neurons in the medial temporal lobe of humans represent view-invariant facial identity. This finding suggests a relatively sparse representation that may be employed for memory formation. Finally, we summarize our recent study, showing that the population of face cells in the anterior ventral inferior temporal cortex of monkeys that represent view-invariant facial identity, can also represent learned paired associations between an abstract picture and a particular facial identity, extending our understanding of the function of the anterior ventral inferior temporal cortex in the recognition of associative meanings of faces.