以功能性磁振造影探討左利手的語言側化

Abstract

此研究以功能性磁振造影探討左利手的語言側化情形。本研究募集母語為中文之左利、右利受試者各20名，讓他們參與語意流暢作業和同音判斷作業，研究布洛卡語言區和後側前額葉皮質的活化狀況，並以加權側化指數研究其大腦語言側化情形。結果顯示，非典型語言側化在右利手族群佔了5%，與過去西方之研究一致，然而在左利手族群中，50%在語意流暢測驗中顯示非典型語言側化 (一半為右側化，一半為雙側化)，35%在同音判斷測驗中顯示非典型語言側化 (全為右側化)，此比例與過去西方研究有明顯偏高之情形。由本研究指出，右利手的族群適合以功能性磁振造影探討其語言側化，然而對於左利手族群，則須較小心解釋，也需較多的語言作業探討語言側化的情形。

Functional magnetic resonance imaging (fMRI) research has been found to be a robust method for language lateralization. However, the majority of the subjects examined were right-handed, and relatively less is known about the consistency of language lateralization in left handers. Two fMRI tasks, the verbal fluency and the homophone judgment tasks that involved semantic fluency and phonological processing respectively, were used to examine the language representation in Chinese speaking left-handers. Weighted laterality index (wLI) was calculated for evaluating language lateralization. Our study showed atypical language lateralization in 5% of the right-handers, with similar incidence as previous western findings, but showed greater proportion (35%-50%) in left-handers. This study provided consistent evidence that fMRI is a robust measure in determining language lateralization in Chinese right-handers. However, more caution needs to be taken for left-handers undergoing presurgical planning by using clinical fMRI when the eloquent cortex is the focus, and more than one kind of language tasks may be required.