MOVE

Neural Coding of envelopes, frequency mixtures and consonance

We consider a class of stimuli that contain power in a narrow range of temporal or spatial frequencies. A characteristic of these narrowband signals is that they have a slower amplitude modulation known as an envelope. Such stimuli are common in the visual, auditory and electrosensory systems. We recently identified a neuronal mechanism for extracting and conveying this envelope signal to the next pyramidal cell layer. We explain how it is based on nonlinearity and slow synap-tic responses, and how gating of this envelope to higher brain can be controlled by noise. We discuss the implications of these findings for social communication, e.g. in the context of weakly electric fish, and for musical perception. Finally we discuss recent results on how the correlation structure of spatio-temporal noise can induce activity in the gamma range in feedback networks involving these same pyramidal cells.