Summary

This chapter covers plasticity in the central auditory system, most notably in the auditory cortex, from a variety of viewpoints. Neuroanatomical and neurophysiological studies in animals as well as behavioral and functional imaging studies in humans will be considered. Plasticity in the auditory system will be compared to plasticity in other sensory systems, and the reorganization of the central auditory system during early blindness and deafness will be discussed. The findings from research in auditory cortical plasticity have important implications for the design of auditory prostheses, such as cochlear implants, in the deaf, and visual prostheses in the blind using nonvisual modalities. They also further the understanding and treatment of common ailments, including hearing loss and tinnitus in an aging population as well as the effects of otitis media in young children.

Introduction

Auditory cortex plays a crucial role in higher perceptual and cognitive functions, including those of speech and music, and in the processing of auditory space. Cortical plasticity, as in other sensory systems, is used to fine-tune these higher functions and plays an important role in reorganization after early injury. Auditory cortical plasticity can be demonstrated after lesions of the cochlea and appears to participate in generating tinnitus. Early musical training leads to an expansion of auditory cortex representing complex harmonic sounds. Similarly, the early phonetic environment has a strong influence on speech development and, presumably, cortical organization of speech.