Neuroplasticity in deafness: Evidence from studies of patients with cochlear implants

Abstract

Deafness alters the normal connectivity needed for an optimally functioning sensory system—resulting in deficits in speech perception and cognitive functioning. Cochlear implants have been a highly successful intervention because they bypass cochlear damage and directly stimulate the auditory nerve and brain, taking advantage of high degree of neuroplasticity of the auditory cortex. Deaf adults and children who receive intervention with cochlear implants have provided a unique platform to examine the trajectories and characteristics of deprivation-induced and experience-dependent neuroplasticity in the central auditory system. I will describe changes in neural resource allocation secondary to hearing impairment, cross-modal cortical re-organization from the visual and somatosensory modalities, and the multimodal and cognitive re-organization that results from auditory deprivation. Overall, it appears that the functional activation of cognitive circuitry resulting from cortical reorganization in deafness is predictive of outcomes after intervention with electrical stimulation. A better understanding of cortical functioning and reorganization in auditory deprivation has important clinical implications for optimal intervention and re-habilitation of cochlear implanted patients. [Work supported by NIH.]