Published online by Cambridge University Press: 14 August 2009
Neural responses to face stimuli may seem like an unwieldy subject for investigating population activity: neurons with face-selective responses are many synapses removed from sensory input, the coding for faces appears to be very sparse, and the stimuli are complex making “proper” control stimuli difficult to come by. So why bother? To the extent that population coding underlies certain cognitive abilities, then those activities that are biological imperatives for the animal should be given “neural priority.” In the rat, foraging and spatial localization relative to “home” points is one critical natural behavior. In primates, social cognition is essential. With the face at the heart of social communication and identification of social status, it should not come as a surprise that neurons appear to “care” about face stimuli in a way not seen for many non-face objects. But the nature of perceiving and learning about facial signals, in terms of population dynamics, is very under-explored territory. Surprisingly, in regions most often associated with face-selective responses, the conclusion of some researchers has been that population activity may add little to nothing to the perception of faces. The current state of knowledge regarding neural bases of face perception will be discussed. The role, if any, of population dynamics, will then be explored. Specifically, the population interactions of face-processing systems across space (e.g. circuits), and time (e.g. oscillations) will be discussed.