Kevin A. Davis
- Ph.D., Boston University, 1995
Adjunct Associate Professor
- Biomedical Engineering
Research in the Auditory Processing Laboratory investigates the encoding, representation, and transformation of acoustic information within the auditory system. The goal is to understand how the brain represents and perceives the acoustic environment and how the neural systems in the brain are organized to create this representation. Our approach combines single- and multi-unit recording and analysis techniques, pharmacological manipulations, and computer modeling studies.
Current interest centers on the inferior colliculus (IC) because it occupies a pivotal position in the central auditory system; it receives direct inputs from most, if not all, of the auditory nuclei in the brainstem and, in turn, provides nearly all of the input to the auditory forebrain. Anatomical evidence suggests that the projections to the IC form highly organized synaptic domains with both segregated and shared sources of input. In support of this parallel processing model, our recent electrophysiological studies have discovered three principal IC response types that appear to be uniquely specialized for the neural encoding of spectral cues for sound localization, narrowband signals in noise, and binaural level and timing information. Based on correlations with response properties in lower-order nuclei, it has been hypothesized that each IC unit type reflects a dominant excitatory input from the medial superior olive, the lateral superior olive, or the dorsal cochlear nucleus. We are now performing experiments designed to provide direct evidence for these functional connections. In addition, we are exploring the functional consequences of this synaptic organization by comparing the quality of acoustic representations in IC target neurons and their sources of input. A question of particular interest in these latter experiments is how the ascending inputs to the IC interact with each other and a rich intrinsic inhibitory circuitry to enhance the processing of sound localization information.