Article
Insights and hurdles in the recording and interpretation of auditory event-related potentials in cochlear implant recipients
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Published: | May 31, 2005 |
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Auditory event-related potentials (AERPs) are measures of electrical brain activity that reflect higher level cognitive processing. As such, they are well suited to probe how a cochlear implant (CI) affects the brain processes that underlie auditory perception. In a series of studies that will be presented we investigated the effects of onset of deafness prior to the acquisition of language, auditory deprivation, and partial restoration of hearing by a CI on the time-course and brain structures involved in auditory processing. AERPs were recorded from pre-lingual children and post-lingual adult CI recipients, and from a group of normal hearing (NH) subjects, while performing non-linguistic and linguistic discrimination tasks. Low resolution electromagnetic tomography (LORETA) was utilized to estimate the smoothest possible three-dimentional current distribution in the brain that generated the observed AERPs. Results indicated that (1) the recording of AERPs from CI recipients was significantly confounded by the electromagnetic field generated by the CI coil (i.e. CI artifact) (2) AERPs were sensitive to increasing acoustic-phonetic complexity (3) LORETA estimations implied different brain activation patterns to non-linguistic and linguistic stimuli in CI recipients compared to NH subjects. In addition, differential laterality patterns of activation were found among patients with right versus left implants. The implications of these results and their relationship to behavioral performance will be discussed.