ABSTRACT
Sensitivity to interaural time disparities (ITDs) is known to be one of the important cues for sound localization. This chapter reviews the physiological and anatomical mechanisms by which ITDs are encoded in the mammalian central auditory system. All of the essential attributes of the model first put forth by Jeffress in 1948 have been confirmed in recent studies of the medial superior olive (MSO). The model posits three assumptions: Cells in the MSO receive afferent inputs from the anteroventral cochlear nucleus that carry timing information about the acoustic stimulus, the binaural cells behave like coincidence detectors, or cross-correlators, and the anatomical projections of afferents to the MSO from the contralateral cochlear nucleus take the form of neuronal delay lines. The result of these assumptions is that a spatial map of ITDs is created along the rostral-caudal axis of the MSO. Evidence supporting the three assumptions and the resulting spatial map are presented.
