Neural mechanisms of localization dominance

University Of Oregon, Eugene OR

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Abstract

[unreadable] DESCRIPTION (provided by applicant): In nature, sounds from a source of interest often arrive at the ears followed closely by reflections from objects in the environment. Despite the superposition of direct and reflected sound, which can degrade sound-localization cues, listeners are able to localize and characterize the true source of the sound. The precedence effect refers to a cluster of perceptual phenomena related to the extraction of valid directional cues from reverberant sounds. I concentrate on one component, localization dominance, in which subjects, when presented with sounds from two loci in rapid succession, tend to perceive a single sound coming from the location of the leading source. The barn owl is a nocturnal predator that tracks its prey guided by a midbrain map of auditory space. A close inspection of how space-specific neurons respond to a lagging sound reveals a brief burst in spike rate, evoked by the onset of the reflection, followed by a second burst, evoked at the offset of the leading sound. Either burst may be the signal that prompts owls to localize the reflection. I propose using neurophysiological and psychophysical experiments to determine which of these two spike bursts is salient and which burst most closely parallels the time course of localization dominance. [unreadable] [unreadable] [unreadable]