Cortical plasticity is the neural mechanism by which the cerebrum adapts itself to its environment, while at the same time making it vulnerable to impoverished sensory or developmental experiences. Like the visual system, auditory development passes through a series of sensitive periods in which circuits and connections are established and then refined by experience. During these periods, the functional maturation of auditory processing and perception is critically dependent on adequate auditory experience. Unfortunately, in cases of sensory deprivation, such as congenital deafness, this process is arrested. Fortunately, it appears that this situation can be reversed in individuals that receive cochlear prosthetics.
Current research is expanding our understanding of cerebral processing and organization in the deaf. In the congenitally deaf, higher-order areas of "deaf" auditory cortex demonstrate significant crossmodal plasticity with neurons responding to visual and somatosensory stimuli. This crucial cerebral function results in adaptive, compensatory plasticity. Not only can the remaining inputs reorganize to substitute for those lost, but this additional circuitry also confers enhanced abilities to the remaining systems. In this presentation, we will review our present understanding of the structure and function of “deaf” auditory cortex using psychophysical, electrophysiological, and connectional anatomy approaches and consider how this knowledge informs our expectations of the capabilities of cochlear implants in the developing brain.