title: Intelligent information loss: the coding of facial identity, head pose, and non-face information in the macaque face patch system.
abstract: Faces are a behaviorally important class of visual stimuli for primates. Recent work in macaque monkeys has identified six discrete face areas where most neurons have higher firing rates to images of faces compared with other objects (Tsao et al., 2006). While neurons in these areas appear to have different tuning (Freiwald and Tsao, 2010; Issa and DiCarlo, 2012), exactly what types of information and, consequently, which visual behaviors neural populations within each face area can support, is unknown. Here we use population decoding to better characterize three of these face patches (ML/MF, AL, and AM). We show that neural activity in all patches contains information that discriminates between the broad categories of face and nonface objects, individual faces, and nonface stimuli. Information is present in both high and lower firing rate regimes. However, there were significant differences between the patches, with the most anterior patch showing relatively weaker representation of nonface stimuli. Additionally, we find that pose-invariant face identity information increases as one moves to more anterior patches, while information about the orientation of the head decreases. Finally, we show that all the information we can extract from the population is present in patterns of activity across neurons, and there is relatively little information in the total activity of the population. These findings give new insight into the representations constructed by the face patch system and how they are successively transformed.
authors.affiliation: School of Cognitive Sciences, Hampshire College, Amherst, Massachusetts 01002, The Center for Brains, Minds and Machines, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, emeyers@hampshire.edu.
authors.forename: Ethan M
authors.identifier: http://orcid.org/0000-0001-5088-6098
authors.initials: EM
authors.lastname: Meyers
authors.affiliation: The Center for Brains, Minds and Machines, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114.
authors.forename: Mia
authors.identifier: http://orcid.org/0000-0001-9564-3209
authors.initials: M
authors.lastname: Borzello
authors.affiliation: The Center for Brains, Minds and Machines, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Laboratory of Neural Systems, The Rockefeller University, New York, New York 10065, and.
authors.forename: Winrich A
authors.initials: WA
authors.lastname: Freiwald
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91126.
authors.forename: Doris
authors.initials: D
authors.lastname: Tsao
mesh_terms: D000818:Animals; D005149:Facial Expression; D019416:Head Movements / Q000502:physiology*; D007360:Intelligence / Q000502:physiology*; D008251:Macaca; D008253:Macaca mulatta; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D011897:Random Allocation; D014793:Visual Cortex / Q000502:physiology*
keywords: face processing; face recognition; macaque; neural decoding; population coding