Abstract
Cochlear implants (CIs) are auditory prostheses which restore hearing via electrical stimulation of the auditory nerve. The successful adaptation of auditory cognition to the CI input depends to a substantial degree on individual factors. We pursued an electrophysiological approach toward an analysis of cortical responses that reflect perceptual processing stages and higher-level responses to CI input. Performance and event-related potentials on two cross-modal discrimination-following-distraction (DFD) tasks from CI users and normal-hearing (NH) individuals were compared. The visual-auditory distraction task combined visual distraction with following auditory discrimination performance. Here, we observed similar cortical responses to visual distractors (Novelty-N2) and slowed, less accurate auditory discrimination performance in CI users when compared to NH individuals. Conversely, the auditory-visual distraction task was used to combine auditory distraction with visual discrimination performance. In this task we found attenuated cortical responses to auditory distractors (Novelty-P3), slowed visual discrimination performance, and attenuated cortical P3-responses to visual targets in CI users compared to NH individuals. These results suggest that CI users process auditory distractors differently than NH individuals and that the presence of auditory CI input has an adverse effect on the processing of visual targets and the visual discrimination ability in implanted individuals. We propose that this attenuation of the visual modality occurs through the allocation of neural resources to the CI input.
Highlights
Cochlear implants (CIs) bypass a non-functional inner ear by a direct electrical stimulation of the auditory nerve
The auditory-visual distraction task was used to combine auditory distraction with visual discrimination performance. In this task we found attenuated cortical responses to auditory distractors (Novelty-P3), slowed visual discrimination performance, and attenuated cortical P3-responses to visual targets in CI users compared to NH individuals
The present study revealed initial evidence that the allocation of attentional resources in CI users is altered in an auditory-visual DFD
Summary
Cochlear implants (CIs) bypass a non-functional inner ear by a direct electrical stimulation of the auditory nerve. Compared to normal acoustic hearing, sounds transmitted through the CI are degraded (Drennan and Rubinstein, 2008). Following CI implantation, the (re-)acquisition of speech intelligibility is considered as a desirable result of CI rehabilitation (Krueger et al, 2008). Until now, it remains unknown how auditory cognition adapts to the degraded input from the CI. Many CI users, experience difficulties in more challenging listening tasks such as speech intelligibility in noise (Wilson and Dorman, 2008) and it is well recognized by the field that the individual CI outcomes is difficult to predict (Peterson et al, 2010). It has been discussed that higher-order, central resources might play a role in CI rehabilitation (Pichora-Fuller and Singh, 2006; Pichora-Fuller, 2006, 2008; Humes, 2007)
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