Development and plasticity of the auditory cortex

Abstract

The primary auditory cortex and the auditory association area are different not only in their cytoarchitecture but also in their timing of myelinization during development. Our PET (positron emission tomography) studies on profoundly deaf cochlear implant (CI) users have added some knowledge on the development and plasticity of the auditory cortex. Speech activation of the auditory association area was found to be poor in prelingually deafened CI users. Although the auditory association area in prelingually deafened children may develop if they continue to use CI, there is a possibility that the development of speech recognition networks in the superior temporal cortex may compete with that of visual language processing. In postlingually deafened subjects, speech recognition networks in the auditory cortex are maintained for a long time even without auditory input. We also found that cortical activities in the auditory association area, Broca's area and the supplementary motor area are increased when decoding speech coded by cochlear implants.