Upper and Lower Levels of the Auditory System: A Contrast of Structure and Function

Abstract

This paper will attempt to illustrate some principles of sensory systems by contrasting features of the organization, and of the functional consequences of that organization, at upper and lower levels of the auditory pathway. For this purpose, the second order cell station or ventral cochlear nucleus (VCN), and the primary auditory cortex of the cat have been chosen for comparison. It will be pointed out that at the lower level a simple systematic organization leads to responses of individual neurones which are straightforward as a function of both static and dynamic stimulus parameters, whereas at the cortical level such as systematic organization is not found, and the neurones are particularly responsive to dynamic parameters of the stimulus. Many neurones in the auditory cortex in their responses emphasize certain features of the sound stimulus; they therefore appear to act in a manner analogous to neurones found in the visual cortex [1]; in the auditory case the abstraction is in terms of temporal features of a complex dynamic sound stimulus.