SOUND-INDUCED ACTIVATION OF AUDITORY CORTICES IN COCHLEAR IMPLANT USERS WITH POSTLINGUAL AND PRELINGUAL DEAFNESS DEMONSTRATED BY POSITRON EMISSION TOMOGRAPHY

Changes of regional cerebral blood Row (rCBF) in the auditory cortices induced by sound stimulation were examined in nine postlingually and five prelingually deaf cochlear implant (CI) users by O-15-labeled wat er Positron Emission Tomography, and the results were compared with th ose of eight normal volunteers. Speech stimulation caused significantl y greater rCBF increase compared with noise stimulation in the auditor y association area in normal and postlingually deaf subjects. In preli ngually deaf subjects, however, speech activation of the auditory asso ciation area was much less than that found in either of the other two groups. Neuronal networks for speech sound processing in the auditory association area in postlingually deaf individuals are thought be simi lar to those in normal subjects, while those in prelingually deaf pati ents who received CI after the speech acquisition period may not devel op completely.