The Macaque Face Patch System: A Window into Object Representation.

The macaque brain contains a set of regions that show stronger fMRI activation to faces than other classes of object. This "face patch system" has provided a unique opportunity to gain insight into the organizing principles of IT cortex and to dissect the neural mechanisms underlying form perception, because the system is specialized to process one class of complex forms, and because its computational components are spatially segregated. Over the past 5 years, we have set out to exploit this system to clarify the nature of object representation in the brain through a multilevel approach combining electrophysiology, anatomy, and behavior. These experiments reveal (1) a remarkably precise connectivity of face patches to each other, (2) a functional hierarchy for representation of view-invariant identity comprising at least three distinct stages along the face patch system, and (3) the computational mechanisms used by cells in face patches to detect and recognize faces, including measurement of diagnostic local contrast features for detection and measurement of face feature values for recognition.