DEPRIVATION EFFECTS ON CENTRAL AUDITORY SYSTEM FUNCTION

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The long-term objective of this research is to understand the way in which deprivation of normal auditory experience affects the development and function of the central auditory system (CAS), and specifically how deprivation affects the complex coding properties of this system. While comprehensive, systematic studies have been done to define and understand the effects of deafferentation resulting from end organ damage, the same approach has yet to be applied to investigation of deprivation of sound input in a normally innervated system. This research will enhance our understanding of the impact of conductive hearing loss on the development of speech and language skills in the young child, and on sound processing in adults with similar deficits. This application formulates a series of questions which are critical to our understanding of this problem, and proposes a series of experiments which will give insight into the nature of the deficit created by a conductive hearing loss. The focus of these initial studies is on defining the effect of deprivation on short term presynaptic changes in auditory system activity and associated measures of metabolic function, and then defining structural modifications in the CAS that may occur secondary to these functional changes. We propose herein a systematic study of the consequences of deprivation, including determination of multiunit electrophysiologic activity and a study of metabolic function, including protein synthesis, enzyme activity, and glucose utilization in the CAS. We propose to follow these studies with a detailed analysis of terminal field organization in third order, binaurally innervated, neurons of the lateral superior olivary nucleus. These studies will form the framework for more detailed studies of synaptic organization and physiological coding properties in future studies.