Department:
Neuroscience
Education:
Ph.D., University of Michigan
Research Description:
The ability to localize the source of a sound is an important function of the auditory system. It may be essential for both prey and predator to quickly and accurately identify the location of a sound source. Consequently, the mechanisms underlying sound localization have been of much interest to psychophysicists, anatomists and physiologists studying the auditory system. Our lab has been studying the physiological and anatomical mechanisms by which sound localization cues are encoded in the central auditory system. It is probably safe to say that we understand more about the central processing of sound localization cues than that of any other auditory attribute (e.g. pitch or loudness). Presently, the laboratory has two major directions of research; one aims to understand the neural circuitry for encoding the acoustic cues used in localization and the other uses behavioral methods to study localization in awake, behaving animals. To study the anatomical and physiological circuits that are important, we record from single cells in various auditory nuclei in the brainstem of anesthetized animals while delivering simple or complex acoustic stimuli that contain various localization cues. We have studied the two circuits that are thought to be involved in encoding the two major binaural cues: interaural time disparities and interaural level differences. In some experiments we record intracellularly and inject the neuron after characterizing it physiologically to allow us to study its anatomical features. For example, the largest synapse in the nervous system can be found in the circuit leading to the lateral superior olive. To link the physiology with behavior, we train cats to look at sound sources and then record from them while they are actively engaged in the task. The eye movements of the cat are monitored while it works in an operant conditioning paradigm. This allows us to study the natural response of cells without the confounding anesthesia as well as the psychophysical abilities of the cat.
Key Words:
Binaural sound localization behavior, interaural time disparities, interaural level disparities