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Neural Plasticity
Volume 2013 (2013), Article ID 318521, 11 pages
http://dx.doi.org/10.1155/2013/318521
Research Article

Cortical Plasticity after Cochlear Implantation

1Center for Functionally Integrative Neuroscience, Aarhus University Hospital, Nørrebrogade 44, Building 10G 6th, 8000 Aarhus C, Denmark
2Royal Academy of Music, Skovgaardsgade 2a, 8000 Aarhus C, Denmark
3Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, 2200 København N, Denmark
4Center for Semiotics, Aarhus University, Building 1485, Office 620, Jens Chr. Skous Vej, 8000 Aarhus C, Denmark

Received 7 July 2013; Accepted 4 October 2013

Academic Editor: Anthony J Hannan

Copyright © 2013 B. Petersen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The most dramatic progress in the restoration of hearing takes place in the first months after cochlear implantation. To map the brain activity underlying this process, we used positron emission tomography at three time points: within 14 days, three months, and six months after switch-on. Fifteen recently implanted adult implant recipients listened to running speech or speech-like noise in four sequential PET sessions at each milestone. CI listeners with postlingual hearing loss showed differential activation of left superior temporal gyrus during speech and speech-like stimuli, unlike CI listeners with prelingual hearing loss. Furthermore, Broca’s area was activated as an effect of time, but only in CI listeners with postlingual hearing loss. The study demonstrates that adaptation to the cochlear implant is highly related to the history of hearing loss. Speech processing in patients whose hearing loss occurred after the acquisition of language involves brain areas associated with speech comprehension, which is not the case for patients whose hearing loss occurred before the acquisition of language. Finally, the findings confirm the key role of Broca’s area in restoration of speech perception, but only in individuals in whom Broca’s area has been active prior to the loss of hearing.