Auditory communication often involves sounds that have complex frequencies, or spectra, and complex timing relations, or temporal pattern. Some analysis of the spectral and temporal components is known to occur low in the brainstem, which contains groups of nerve cells called the auditory nuclei. These neurons send projections to higher centers in the brain for further analysis. Frogs have provided particuluarly useful models for study, since they are well-studied, their mating calls are relatively simple and stereotyped, and the brainstem has somewhat simpler structure than in mammals. This project will use the frog model to examine how behaviorally meaningful features of complex sounds are processed in the brain. Two particular nuclei in the brain stem will be studied by electrophysiological recording of single cell responses to a wide range of artificial and natural acoustic signals. Building on past work on recognition in the frequency domain, this project will aim primarily to determine the selective importance of certain features of amplitude modulation and temporal pattern, and the neural codes of response patterns that may be used to discriminate among different signals. Results will be relevant to studies of communication behavior, of complex sound analysis, and important to the general sensory problem of signal processing.
