The brain requires many functions to span the gap from visual sensation to perception. Our studies indicate that different visual areas in the brain may communicate via temporally modulated messages. These findings suggest that understanding temporally encoded messages may give clues to the types of functional processes involved in visual information processing. New evidence suggests one such functional role for neurons in inferior temporal (IT) cortex during a short-term visual memory task. In all visual areas studied, neurons encode information about pictures in a multidimensional temporal code. We are recording from individual neurons during a color-versus-form discrimination task. It appears that neurons in the IT cortex send four messages during a pattern recognition task: Two messages describe the color and form of the visual cue, and two describe the color and form of the visual target. These results lead to a new hypothesis concerning the role of visual neurons in discrimination tasks. The multiplex-code hypothesis states that neurons carry separate color and form messages, multiplexed together. The temporal waveform of the response of visual neurons is formed by multiplying these two waveforms together.
