Evolution of crossmodal reorganization of the voice area in cochlear-implanted deaf patients

• Published in: Human brain mapping Vol. 33; no. 8; pp. 1929 - 1940
• Main Authors: Rouger, Julien, Lagleyre, Sébastien, Démonet, Jean-François, Fraysse, Bernard, Deguine, Olivier, Barone, Pascal
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-08-2012; Wiley-Liss; John Wiley & Sons, Inc; Wiley
• Subjects: Adult; Aged, 80 and over; Biological and medical sciences; Brain - physiology; Brain Mapping; cochlear implant; Cochlear Implants; crossmodal compensation; deafness; Deafness - physiopathology; Deafness - surgery; Female; Human viral diseases; Humans; Infectious diseases; Investigative techniques, diagnostic techniques (general aspects); Life Sciences; Lipreading; Male; Medical sciences; Middle Aged; multisensory integration; Nervous system; Neuronal Plasticity - physiology; Neurons and Cognition; Photic Stimulation; Positron-Emission Tomography; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Speech Perception - physiology; speechreading; Viral diseases; Viral diseases of the lymphoid tissue and the blood. Aids; Visual Perception - physiology; voice area; Human; Nervous system diseases; Implant; Radiodiagnosis; Auditory disorder; Multisensory integration; Crossmodal interaction; crossmodal compensation; Hearing loss; voice area; cochlear implant; speechreading; Compensation; ENT disease; Evolution; deafness; Voice; multisensory integration
• ISSN: 1065-9471; 1097-0193
• DOI: 10.1002/hbm.21331

Psychophysical and neuroimaging studies in both animal and human subjects have clearly demonstrated that cortical plasticity following sensory deprivation leads to a brain functional reorganization that favors the spared modalities. In postlingually deaf patients, the use of a cochlear implant (CI) allows a recovery of the auditory function, which will probably counteract the cortical crossmodal reorganization induced by hearing loss. To study the dynamics of such reversed crossmodal plasticity, we designed a longitudinal neuroimaging study involving the follow‐up of 10 postlingually deaf adult CI users engaged in a visual speechreading task. While speechreading activates Broca's area in normally hearing subjects (NHS), the activity level elicited in this region in CI patients is abnormally low and increases progressively with post‐implantation time. Furthermore, speechreading in CI patients induces abnormal crossmodal activations in right anterior regions of the superior temporal cortex normally devoted to processing human voice stimuli (temporal voice‐sensitive areas‐TVA). These abnormal activity levels diminish with post‐implantation time and tend towards the levels observed in NHS. First, our study revealed that the neuroplasticity after cochlear implantation involves not only auditory but also visual and audiovisual speech processing networks. Second, our results suggest that during deafness, the functional links between cortical regions specialized in face and voice processing are reallocated to support speech‐related visual processing through cross‐modal reorganization. Such reorganization allows a more efficient audiovisual integration of speech after cochlear implantation. These compensatory sensory strategies are later completed by the progressive restoration of the visuo‐audio‐motor speech processing loop, including Broca's area. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc