Physiological and anatomical studies relevant to considerations of sound localization in mammals

Abstract

Recent studies of the basic organization and response properties of neurons of auditory nuclei and auditory cortical fields bear important implications for considerations of how sound localization behavior is a product of these systems. First, a series of largely parallel, functionally distinct projection subsystems have been identified. Some general conclusions as to their individual roles in auditory behavior can be drawn, given response properties of neurons and connections within. There are sheetlike subdivisions oriented orthogonally to isofrequency contours, in the central nucleus of the inferior colliculus, the ventral division of the MGB and in several auditory cortical fields. They are completely interconnected from level to level. In cortical fields and in the central nucleus, these subdivisions have been demonstrated to be response specific. Some would appear to be involved in specific aspects of sound localization, others not. Second, it now appears likely that low‐frequency pitch sensation is decoded within the medial superior olive, a nucleus long implicated in sound localization. The conjoint information processing accomplishments in these two psychoacoustic dimensions and some of its functional implications will be discussed. [Supported by NIH Grant NS‐10414.]