Speech-associated brain areas activated by visual stimuli in adults with cochlear implants: a functional near-infrared spectroscopy study

Studies of cross-modal reorganization showed different results regarding the correlation between visual activation of speech-associated brain regions and the restoration of speech understanding in cochlear implant (CI) users. In this study, we employed functional near-infrared spectroscopy (fNIRS) to measure neural responses in speech-associated cortical areas to two types of visual stimuli—sound photos (images that evoke imagined sounds) and nonsound photos—in both CI users and normal-hearing adults. Nonsound photos elicited significantly greater activation in the right Broca’s area among CI users compared to normal hearing group. Furthermore, activation of the left Wernicke’s area in response to nonsound photos was positively correlated with Disyllabic Word Recognition (DWR) scores in the CI group. These findings demonstrate that in CI users, speech-associated brain regions respond differentially to visual stimuli with and without implied auditory content. These findings indicate specific cortical reorganization patterns in CI users, which provide insights into their speech perception abilities and potential rehabilitation strategies.