Visual processing of faces in temporal cortex: physiological evidence for a modular organization and possible anatomical correlates.

Physiological recordings along the length of the upper bank of the superior temporal sulcus (STS) revealed cells each of which was selectively responsive to a particular view of the head and body. Such cells were grouped in large patches 3-4 mm across. The patches were separated by regions of cortex containing cells responsive to other stimuli. The distribution of cells projecting from temporal cortex to the posterior regions of the inferior parietal lobe was studied with retrogradely transported fluorescent dyes. A strong temporoparietal projection was found originating from the upper bank of the STS. Cells projecting to the parietal cortex occurred in large patches or bands. The size and periodicity of modules defined through anatomical connections matched the functional subdivisions of the STS cortex involved in face processing evident in physiological recordings. It is speculated that the temporoparietal projections could provide a route through which temporal lobe analysis of facial signals about the direction of others' attention can be passed to parietal systems concerned with spatial awareness.