Animal models of auditory temporal processing.

Human temporal processing relies on bottom-up as well as top-down mechanisms. Animal models thereof, in the vast majority, are only probing the bottom-up mechanisms. I will review the vast literature underlying auditory temporal processing to elucidate some basic mechanisms that underlie the majority of temporal processing findings. Some basic findings in auditory temporal processing can all be based on mechanisms determining perstimulatory adaptation of firing rate. This is based on transmitter release mechanisms in peripheral as well as central synapses. It is surprising that the adaptation and recovery time constants that define perstimulatory firing rate adaptation are not very different between auditory periphery and auditory cortex when probed with similar stimuli. It is shown that forward masking, gap and VOT detection, and temporal modulation transfer functions are all directly related to perstimulatory adaptation, whereas stimulus-specific adaptation is at least partly dependent on it. Species differences and the fact that most of the studies reviewed were done in anesthetized animals need to be taken into account when extrapolating animal findings to human perceptual studies. In addition, the accuracy of first-spike latency plays a major role in sound localization and in the brainstem mechanisms for periodicity pitch and forms the basis for understanding evoked potential studies in humans. These mechanisms are also crucial for determining neural synchrony underlying perceptual binding and some important aspects of stream segregation.