Research Interests
Neural mechanisms of audition in anurans
Acoustic communication plays an important role in the reproductive behavior of anuran amphibians (frogs and toads). Much of the information in these vocalizations is encoded in the temporal structure (e.g. pulse repetition rate). The anuran auditory system, therefore, is well suited for investigating how the temporal structure of sound is represented at various stages in the auditory nervous system. We are particularly interested in understanding the mechanisms that underlie transformations in these representations. For example, the periodic modulations in the amplitude of sound are coded in the peripheral auditory system by the periodic fluctuations in the discharge rate of these neurons. At the midbrain, however, this 'periodicity' coding is replaced by a 'temporal filter' coding scheme wherein individual neurons selectively respond to particular rates of amplitude modulation. The mechanisms that underlie this transformation are unknown. Recent neurophysiological and behavioral studies indicate that integration of time-dependent excitation and inhibition underlies selectivity of midbrain neurons for temporal features of communication signals. Recent efforts to focally apply pharmacological agents in conjunction with whole-cell recording, in vivo, promise to provide deep insights into the mechanisms that underlie temporal computations in the auditory system. Comparative studies of treefrogs and chorus frogs are also underway. These studies are aimed at further elucidating mechanisms that underlie selectivity for temporal features of communication sounds, and how changes in temporal processing contribute to speciation; we are particularly interested in how polyploidy and interspecific interactions influence the temporal processing properties of midbrain neurons e.g., pulse shape selectivity. This work should provide insight into how changes in the functional organization of the central auditory system contribute to the evolution of new species.
