Brains Organize Based on Sound
Giraud, Lazard, and Lee (2011) report they have identified neural patterns that consistently predict speech performance acquired via cochlear implants. They note, that deaf subjects with neural activity in ventral regions of the brain are generally the worst performers, while deaf subjects with neural activity in the dorsal regions are most often the best performers. Of note, hypo-metabolism at rest indicates the temporal lobe is less active in deaf subjects as compared to hearing subjects; and this is essentially a good sign in that the cochlear implant (CI) will stimulate these same regions as they have remained primarily auditory, and not have been dominated by other cognitive functions; such as lip-reading.
Further, if the temporal lobe appears to be active at rest (in deaf subjects), it appears likely it has become involved in other cognitive tasks (other than speech processing) and thus, it is “no longer susceptible to auditory stimulation.” The authors agree that early implantation in appropriate candidates is best as it is most likely to “maintain or correct the specificity of auditory wiring.” Giraud, Lazard, and Lee report knowledge of the functional organization of the brain at rest (and during linguistic tasks) may be beneficial with regard to predicting the outcome from cochlear implantation.
For More Information, Recommendations, and References
Eggermont JJ. (2008) The Role of Sound in Adult and Developmental Auditory Cortical Plasticity. Ear & Hearing. 29(6).
Giraud AL, Lazard D, Lee HJ. (2011) Cochlear Implant Outcome and Functional Brain Organization in Deaf Subjects. Seminars in Hearing 32(2):142-146.