Karns, Dow, and Neville (2012), from the Department of Psychology and Institute of Neuroscience at the University of Oregon in Eugene, Oregon, examined "cross-modal neuroplasticity" within Heschl’s Gyrus (the primary auditory cortex) in congenitally deaf humans through functional magnetic resonance imaging (fMRI). The authors used visual, somatosensory, and bimodal stimuli. They reported that Heschl’s Gyrus in deaf people responds to somatosensory stimulation and visual stimuli more than it does in hearing people. With regard to which stimuli was more robust (within Heschel’s Gyrus of deaf people, i.e., visual versus somatosensory) the responses to somatosensory stimuli were larger. Karns, Dow, and Neville demonstrated that deafness can facilitate (or permit) neuroplastic changes in the human brain. Specifically, when the auditory cortex does not receive auditory stimuli, vision and somatosensation may "take over" and use Heschl’s Gyrus to process alternative sensory stimuli.
For More Information, References, and Recommendations
Cardon G, Campbell J, Sharma A. (2012) Plasticityin the Developing Auditory Cortex—Evidence from Children with Sensorineural Hearing Loss and Auditory Neuropathy Spectrum Disorder. Journal of the American Academy of Audiology 23:396-411.
Giraud AL, Lazard D, Lee HJ. (2011) Cochlear Implant Outcome and Functional Brain Organization in Deaf Subjects. Seminars in Hearing 32(2):142-146.
Karns CM, Dow MW, Neville HJ. (2012) Altered Cross-Modal Processing in the Primary Auditory Cortex of Congenitally Deaf Adults: A Visual-Somatosensory fMRI Study with a Double-Flash Illusion. The Journal of Neuroscience 32(28): 9626-9638.