Visual cortex activation decrement following cochlear implantation in prelingual deafened children

ObjectiveVisual take-over of the auditory cortex in prelingual deaf children has been widely reported. However, there have been few studies on visual cortex plasticity after cochlear implantation (CI). In this study, we investigated the hypothesis that extrinsic auditory stimulation following CI in prelingual deafened children can induce visual cortex plasticity.MethodVisual evoked potentials (VEPs) were recorded in 37 CI children (4 groups with different use times) and 8 control subjects, in response to sound and nonsound stimuli. Latency and amplitude were analyzed for the P1, N1 and P2 components on the Oz electrode. Comparisons of VEP were conducted between the sound and nonsound stimuli and among different groups in order to view evidence of visual cortex reorganization.ResultsThe latency of the P2 component was significantly longer at the occipital site (Oz) in CI 0M than those in the other four groups. After the effect of age was excluded, a significant negative correlation was found between CI usage and P2 latency of nonsound stimuli. Occipital P1N1 latency and P1 amplitude were not affected by group or stimulus category. However, the N1 and P2 amplitudes were significantly larger in response to a sound stimulus than to a nonsound stimulus.ConclusionOur findings suggest that P2 latency develops with CI usage and may be a biomarker of visual cortex plasticity.