Functional changes in people with different hearing status and experiences of using Chinese sign language: An fMRI study

Abstract

The purpose of this study was to assess functional changes in the cerebral cortex in people with different sign language experience and hearing status whilst observing and imitating Chinese Sign Language (CSL) using functional magnetic resonance imaging (fMRI). 50 participants took part in the study, and were divided into four groups according to their hearing status and experience of using sign language: prelingual deafness signer group (PDS), normal hearing non-signer group (HnS), native signer group with normal hearing (HNS), and acquired signer group with normal hearing (HLS). fMRI images were scanned from all subjects when they performed block-designed tasks that involved observing and imitating sign language stimuli. Nine activation areas were found in response to undertaking either observation or imitation CSL tasks and three activated areas were found only when undertaking the imitation task. Of those, the PDS group had significantly greater activation areas in terms of the cluster size of the activated voxels in the bilateral superior parietal lobule, cuneate lobe and lingual gyrus in response to undertaking either the observation or the imitation CSL task than the HnS, HNS and HLS groups. The PDS group also showed significantly greater activation in the bilateral inferior frontal gyrus which was also found in the HNS or the HLS groups but not in the HnS group. This indicates that deaf signers have better sign language proficiency, because they engage more actively with the phonetic and semantic elements. In addition, the activations of the bilateral superior temporal gyrus and inferior parietal lobule were only found in the PDS group and HNS group, and not in the other two groups, which indicates that the area for sign language processing appears to be sensitive to the age of language acquisition.