# Reduced Visual‐Cortex Reorganization Before and After Cochlear Implantation Relates to Better Speech Recognition Ability

## TL;DR

This study shows that brain changes in deaf individuals before cochlear implantation predict better speech recognition outcomes after the implant.

## Contribution

The study identifies pre-implant visual cortex reorganization as a predictor of cochlear implant success.

## Key findings

- CI users showed reduced visual cortex activation and stronger visual-auditory connectivity compared to normal-hearing controls.
- Pre-implant visual P1 amplitude correlated positively with post-implant speech recognition ability.
- Cortical changes in CI users were mainly due to auditory deprivation, not CI experience.

## Abstract

Although a cochlear implant (CI) can partially restore auditory function, CI recipients show alterations not only in auditory but also in visual cortical processing. Yet, it is not well understood how these visual changes relate to the CI outcome and to what extent these changes are induced by auditory deprivation and the limited CI input, respectively. Here, we present a prospective longitudinal electroencephalography study which examined the deprivation‐ and CI‐induced alterations on cortical face processing by comparing visual evoked potentials (VEP) in CI users before and 6 months after implantation. A group of normal‐hearing (NH) listeners served as a control. The participants performed a word‐identification task and a face‐categorization task to study the cortical processing of static and articulating faces in attended and unattended conditions. The CI candidates and CI users showed a reduced visual‐cortex activation, a stronger functional connectivity between the visual and auditory cortex, and a reduced attention effect in the (extended) alpha frequency range (8–18 Hz) when compared to NH listeners. There was a positive correlation between the P1 VEP amplitude recorded before implantation and the speech recognition ability after implantation. Our results suggest that the CI users' alterations in cortical face processing are mainly induced by auditory deprivation and not by CI experience. Importantly, these deprivation‐induced changes seem to be related to the CI outcome. Our results suggest that the visual P1 amplitude as recorded before implantation provides an objective index of cortical visual reorganization that may help predict the CI outcome.

Using two different EEG tasks with static and articulating faces, deprivation‐induced cortical changes in postlingually deafened individuals were found by means of reduced visual cortex activation and a relationship between these alterations and the CI outcome after 6 months. These alterations are not significantly affected by CI experience.