Visual perception depends on rich interactions among individual neurons. These interactions depend on mechanisms that encode, process, and transmit information among different visual areas of the brain. We are applying information theory to neurophysiological studies of behavior to learn what role neurons play in forming perceptions. We have already shown that neurons in different areas of the brain encode and transmit information about stationary, two-dimensional pictures that vary in form, brightness, and duration. In all areas studied, neurons encode picture information using a multidimensional temporal code. Neurons can transmit at least three times as much information using a multivariate temporal code as could be transmitted using a univariate strength code. We are now recording from individual neurons during visual discrimination tasks. It appears that neurons in the inferior temporal cortex send two types of messages during a pattern recognition task. One type of message describes the picture, whereas the other type of message indicates that a certain response is called for, without describing the eliciting picture. These results suggest that behavioral and physical parameters of a stimulus may be coupled within a temporal code.
