Non-auditory Processing of Cochlear Implant Stimulation after Unilateral Auditory Deprivation in Children

We have aimed to identify effects of unilateral hearing on the developing brain in a series of studies in children who have one deaf ear and access sound in the other ear through normal hearing, a hearing aid, or a cochlear implant (CI). Multi-channel EEG in these cohorts revealed strengthening of auditory pathways from the hearing ear to the auditory cortices. Response differences found in frontal and precuneus cortical areas in adolescents with long term unilateral CI use suggested involvement of non-auditory cortical areas during passive hearing. We also examined cortical effects of leaving one ear deprived of sound during development in children with unilateral hearing (listed above) who received a CI in their deaf ear. Atypical responses to CI stimulation showed strong activation of the ipsilateral auditory cortex which increased with duration of unilateral deprivation. Graph theory analysis including community detection revealed a network that was organised into a temporal-occipital module and a temporal-frontal module, with left Heschel’s gyrus and left lingual gyrus central to information flow between the two. Results across these studies identify neuroplasticity in children with unilateral hearing/deprivation and suggest that regions outside of the auditory cortex can modulate sound processing through CIs.