Bioacoustics, hearing and the integrative physiology of bats

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The long-term goal of my research program is to understand how the central nervous system encodes and decodes information to produce behaviour. To address this goal in the short-term, I study sound production and the physiology of hearing. Research on mammalian bioacoustics and hearing will be of enormous benefit to understanding behaviours as diverse as speech recognition and music perception by humans and echolocation by bats. My electrophysiology research seeks to determine the physiological mechanisms underlying a specialized form of auditory temporal processing--neural tuning to sound duration--and to relate the mechanism(s) to hearing and behaviour. Studies are conducted on a model hearing organism: the echolocating bat. Bats are ideal subjects for bioacoustical and hearing research because we know what sounds are important to bats and this simplifies the effort of discovering physiological mechanisms. In the auditory midbrain of bats and other mammals there exist neurons with responses highly tuned to signal duration, with different cells having different best durations. The neural circuits that create these duration-tuned neurons are still unclear. This proposal seeks to record action potentials in response to acoustic stimulation to determine how spectral and temporal information is encoded by the mammalian auditory midbrain, and to understand the roles of synaptic excitation and inhibition in creating duration-tuned neurons. To complement our electrophysiology research, we will also create mathematical models that mirror known neuroanatomical connections in the central auditory system to evaluate the biological plausibility of the proposed network connections. We will also study how bat pups change the duration and bandwidth of their frequency modulated (FM) vocalizations as they age. My research on bioacoustics and the physiology of temporal processing in bats addresses broad issues in science, such as why there are multiple processing pathways in the central auditory system and what role they play in hearing (perception) and behaviour (sound production). Knowledge of how the brain analyzes sounds also has direct implications for the diagnosis and treatment of hearing and language disorders.