Binaural Neurons in the Mustache Bat’s Inferior Colliculus: Physiology, Functional Organization, and Behavioral Implications
This report describes how sound localization cues contained within a narrow band of the echo spectrum may be encoded in the auditory midbrain of the mustache bat (Pteronotus parnellii). Binaural neurons were studied in the 60 kHz region of the inferior colliculus (IC), the region in IC that analyzes echoes of the second harmonic, constant frequency (CF) component of the mustache bat’s biosonar signal. In the enlarged 60 kHz region, binaural neurons are spatially segregated and available for detailed study. In particular, the responses of “EI” neurons were studied. These are excited by stimulation of the contralateral ear and inhibited by stimulation of the ipsilateral ear. Recordings of 60 kHz EI single units suggest what features of their response may encode interaural intensity differences (IIDs) and/or horizontal target location. These physiological studies suggest some directions for the behavioral study of echo localization.
KeywordsInferior Colliculus Sound Field Narrowband Signal Interaural Intensity Difference Ipsilateral Field
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