AUDITORY EVENT-RELATED POTENTIALS IN POSTLINGUALLY AND PRELINGUALLY DEAF COCHLEAR IMPLANT RECIPIENTS

The development of central auditory functions in cochlear implant (CI) patients was studied over six months of rehabilitation. Examinations were performed beginning with the first week after processor calibrati on, and in monthly follow-up sessions thereafter. The subjects were gi ven a simple auditory perception task (detection of a 400 Hz and a 145 0 Hz tone), as well as an oddball-paradigm (detection of one of the to nes as a rare deviant). Auditory evoked potentials, reaction time and errors were recorded. Results from five patients, two postlingually de af and three prelingually deaf CI recipients are shown. Generally, in the auditory evoked potentials of patients a shortening of N100 latenc y towards those of subjects with normal hearing was seen from month to month. However, in the prelingually deaf patients this effect was wea ker and more variable over time. Three CI recipients showed a P300 com ponent in the oddball-paradigm in correlation with their performance. Two prelingually deaf patients failed to show a P300 in the oddball-pa radigm. For both components, the N100 and the P300 we found a larger s preading over the skull in the patients compared to a normal hearing p erson. The results show that from the very first days after initial pr ocessor fitting prelingually and postlingually deaf CI recipients may show cortical correlates of stimulus processing and discrimination. Fo r some components of the auditory evoked potentials an initial tempora l change but a maintained larger spreading over the skull was seen.