An fMRI Study of Chinese Sign Language in Functional Cortex of Prelingual Deaf Signers

Using functional magnetic resonance imaging (fMRI), to observe the changes of cerebral functional cortex in prelingual deaf singers for Chinese sign language(CSL). Materials and methods: 14 prelingual deaf singers (PDS) (group I), 13 hearing non-signers (HnS) (group II), 11 hearing native signers (HNS) (group III) and 12 hearing late signers (HLS) (group IV) were scanned on 1.5T MRI scanner while they observed and imitated CSL. Then the AFNI software was applied to find the areas of activation and calculate the volume across subjects. Results: During observing and imitating CSL, the activated areas in all groups include bilateral middle frontal gyrus, middle temporal gyrus, superior parietal lobule, cuneate lobe, fusiform gyrus and lingual gurus. The activation of bilateral inferior frontal gyrus were found in group I , III and IV, but no activation in group II. The activation of bilateral superior temporal gyrus and inferior parietal lobule were found in group I and III, but no activation in others. The volumes of bilateral inferior frontal gyrus in group I were greater than those in group III and IV. The volumes of bilateral superior temporal gyrus in group I were greater than those in group III. The volumes of bilateral superior parietal lobule, cuneate lobe and lingual gurus in group I were greater than those in other groups. The activated areas during imitating CSL were more than those during observing CSL. The volumes of bilateral inferior frontal gyrus, superior parietal lobule and left middle temporal gyrus in imitating task were greater than those in observing task in group I . There were no statistical differences about the volume in the symmetrical functional cortex in all groups during observing and imitating tasks. Conclusion : The cortex in PDS had occurred reorganization, after losing their auditory and learning the CSL. The activation of linguistic cortex can be found during observing and imitating CSL in PDS. The secondary auditory cortex and association area turn to take part in processing visual language when no auditory afference, whereas the primary auditory cortex do not participate the reorganization. Additionally, the visual cortex of PDS is more sensitive than that of normal hearing individuals. The reorganization of cortex in PDS is related to the experience of CSL, but is mainly caused by the effect of hearing loss.