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

Objective To observe the changes of functional cortex in prelingual deaf singers(PDS) for Chinese sign language(CSL) by means of functional magnetic resonance imaging(fMRI).Methods Fourteen PDS(groupⅠ),thirteen hearing non-signers(HnS,groupⅡ),eleven hearing native signers(HNS,group Ⅲ) and twelve 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 area of activation and the volume across subjects was calculated.Results During observing and imitating CSL,the activated areas in all groups included middle frontal gyrus,middle temporal gyrus,superior parietal lobule,cuneate lobe,fusiform gyrus and lingual gurus.The activation of inferior frontal gyrus was found in groupⅠ,Ⅲ and Ⅳ,but not in groupⅡ.The activation of superior temporal gyrus and inferior parietal lobule was found in groupⅠand Ⅲ,but not in the others.The volume of inferior frontal gyrus in groupⅠwas greater than that in group Ⅲ and Ⅳ.The volume of superior temporal gyrus in groupⅠwas greater than that in group Ⅲ.The volume of superior parietal lobule,cuneate lobe and lingual gurus in groupⅠwas greater than that in other groups.The activation areas during imitating CSL were more than those during observing CSL.The volume of bilateral inferior frontal gyri,superior parietal lobules and left middle temporal gyrus in imitating task was greater than that in observing task in groupⅠ.There were no statistical differences about the volume in the symmetrical functional cortex in all groups during observing and imitating tasks.Conclusion The functional cortex in PDS has occurred reorganization,after losing their audition and learning the CSL.The activation of linguistic cortex can be found during oberserving and imitating CSL in PDS.The secondary auditory cortex and association areas turn to take part in processing of visual language when no auditory afference occur,whereas the primary auditory cortex do not participate in the reorganization.Addtionally,the visual cortex is more sensitive than that of hearing individuals.The reorganization of functional cortex in PDS is related with the expericence of CSL,but is mainly caused by the effect of hearing loss.