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Abstract: In congenitally deaf children, chronological age is generally accepted as a critical factor that affects successful rehabilitation following cochlear implantation (CI). However, a wide variance among patients is known to exist regardless of the age at CI [Sarant, J.Z., Blamey, P.J., Dowell, R.C., Clark, G.M., Gibson, W.P., 2001. Variation in speech perception scores among children with cochlear implants. Ear Hear. 22, 18–28]. In a previous study, we reported that prelingually deaf children in the age range 5–7 years at implantation showed greatest outcome variability [Oh S.H., Kim C.S., Kang E.J., Lee D.S., Lee H.J., Chang S.O., Ahn S.H., Hwang C.H., Park H.J., Koo J.W., 2003. Speech perception after cochlear implantation over a 4-year time period. Acta Otolaryngol. 123, 148–153]. Eleven children who underwent CI between the age of 5 and 7 1/2 years were subdivided into a good (above 65%: GOOD) and a poor (below 45%: POOR) group based on the performance in a speech perception test given 2 years after CI. The preoperative 18F-FDG-PET (F-18 fluorodeoxyglucose positron emission tomography) images were compared between the two groups in order to examine if regional glucose metabolic difference preexisted before the CI surgery. In the GOOD group, metabolic activity was greater in diverse fronto-parietal regions compared to the POOR group. In the POOR group, the regions related to the ventral visual pathway showed greater metabolic activity relative to the GOOD group. These findings suggest that the deaf children who had developed greater executive and visuospatial functions subserved by the prefrontal and parietal cortices might be successful in auditory language learning after CI. On the contrary, greater dependency on the visual function subserved by the occipito-temporal region due to auditory deprivation may interfere with acquisition of auditory language after CI. [Copyright &y& Elsevier]

Unlabelled: Frontotemporal dementia (FTD) is a common cause of presenile dementia. The aim of the current study was 2-fold: (a) to delineate the brain regions with reduction of glucose metabolism, and (b) to investigate the hemispheric asymmetry of glucose metabolism in FTD using (18)F-FDG PET., Methods: We compared the regional metabolic patterns on (18)F-FDG PET images obtained from 29 patients with FTD and 11 healthy subjects using a voxel-wise analysis (statistical parametric mapping [SPM]). The hemispheric asymmetry of glucose metabolism was computed based on 2 different measures: one (AI(ROI)) by counting the (18)F-FDG activity of each hemisphere on the normalized and spatially smoothed PET images and the other (AI(SPM)) by counting the number of voxels with significant hypometabolism based on SPM results., Results: Significant hypometabolism was identified in extensive prefrontal areas, cingulate gyri, anterior temporal regions, and the left inferior parietal lobule. Hypometabolism was also found in the bilateral insula and uncus, left putamen and globus pallidus, and medial thalamic structures. Frontal hypometabolism was more prominent in the left hemisphere than in the right. Twenty-six (90%) of the 29 patients with FTD had AI(ROI) values indicating significant lateralization of glucose metabolism; 18 patients had hypometabolism more severe on the left than right side, and only 8 patients had the opposite pattern. Results from AI(SPM) showed similar patterns., Conclusion: The voxel-wise analysis of (18)F-FDG PET images of patients with FTD revealed hypometabolism in extensive cortical regions, such as frontal and anterior temporal areas, cingulate gyri, uncus, and insula and subcortical areas, including basal ganglia (putamen and globus pallidus) and medial thalamic regions. The hemispheric asymmetry of hypometabolism (more frequently lateralized to the left) was common in patients with FTD, which may be another metabolic feature that helps to differentiate FTD from Alzheimer's disease or other causes of dementia.

Unlabelled: Controversy regarding functional reorganization in the adult brain remains. To investigate whether neuroplasticity is present in adults with postlingual deafness, we examined the pattern of cerebral glucose metabolism on (18)F-FDG brain PET images of postlingually deaf patients by comparing the auditory cortical activation pattern with those of age- and sex-matched healthy control subjects. We also correlated the cerebral glucose metabolism in deaf patients with the duration of deafness using statistical parametric mapping., Methods: In the resting state (eye closed, ears unoccluded in a dark and quiet environment), (18)F-FDG brain PET scans were performed on 9 postlingually deaf patients and 9 age- and sex-matched healthy volunteers. Significant increases and decreases of regional cerebral metabolism in the patient group were estimated by comparing their PET images with those of the healthy volunteers using t statistics at every voxel. To reveal regions in which metabolism was significantly correlated with the duration of deafness, the general linear model with the duration of deafness as a covariate was tested at each voxel., Results: When we compared (18)F-FDG brain PET images of postlingually deaf patients with those of age- and sex-matched healthy control subjects by performing a t test at every voxel, the glucose metabolism of deaf patients was significantly (P < 0.001) lower than that of the control subjects in both anterior cingulate gyri (Brodmann area 24 [BA24]) and superior temporal cortices (BA41, BA42) and in the right parahippocampal gyrus. No area showed a significant increase of metabolism in deaf patients with the same threshold. When we correlated glucose metabolism of deaf patients with the duration of deafness after total deprivation of hearing capability using a general linear model with the duration of deafness as a covariate at every voxel, metabolism in both anterior cingulate gyri (BA24) and superior temporal cortices (BA41, BA42) showed a significant (P < 0.005) positive correlation with the duration of deafness., Conclusion: This study suggests that plasticity is present in adult brains of postlingually deaf patients. In the mature brain, auditory deprivation decreased neuronal activity transiently in primary auditory and auditory-related cortices, and, over time, functional reorganization likely takes place in the auditory cortex. Plasticity was prominent in superior temporal and anterior cingulate gyri in the sensory-deprived mature brain and militated against postimplantation improvement in patients with cochlear implants.