Cross-modal plasticity and speech perception in individuals who use a cochlear implant.

다국어 초록 (Multilingual Abstract)

Duration of auditory deprivation is inversely related to speech perception performance after cochlear implantation in individuals with severe-to-profound sensorineural-hearing loss. In deaf adults, auditory areas in the right temporal lobe process peripheral visual motion stimuli. Remapping of auditory cortex to process visual stimuli may limit speech perception performance in individuals who experience prolonged periods of auditory deprivation prior to receiving a cochlear implant. We suggest the development of cross-modal plasticity during prolonged periods of auditory deprivation plays a role in limiting the brain's ability to process speech, once the sensation of hearing is restored through a cochlear implant. This study examines the relationship between the development of visual/auditory cross-modal plasticity and speech perception with a cochlear implant. We assess cross-modal plasticity through the amplitude of visual cortical evoked potential in response to peripheral visual motion, measured over the right temporal lobe. Speech perception ability is measured as percent-correct words and sentences in quiet and noise. Results indicate speech perception scores decline significantly as the amplitude of the cortical evoked response to peripheral visual motion increases for pre-lingually deaf cochlear implant users. No relationship between speech perception scores and the amplitude of the cortical response to peripheral visual motion is found in post-lingually deaf cochlear implant users. Further, no relationship between cross-modal plasticity and the duration of auditory deprivation is observed. Results indicate that cross-modal plasticity negatively influences speech perception ability with a cochlear implant for pre-lingually deaf individuals and that the time during development that auditory deprivation takes place is more important than the duration of auditory deprivation.