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  • 學位論文

自閉症兒童與青少年溝通缺陷之機制

The Underlying Mechanism of Communication Deficits in Children and Adolescents with Autistic Spectrum Disorders

指導教授 : 周泰立
共同指導教授 : 高淑芬(Susan Shur-Fen Gau)

摘要


目的:根據國際診斷標準(DSM-IV,ICD-10),自閉症疾病在臨床上的三大核心症狀為社會互動障礙、溝通障礙、及重複性刻板行為。本研究著重於自閉症的溝通障礙症狀,以中文語意判斷作業進行行為實驗與功能性磁振造影(Functional magnetic resonance imaging, fMRI)實驗,探討8-18歲自閉症患童與青少年,相對於正常發展孩童與青少年,在語意處理的認知與神經機制的異同。方法:實驗操弄三種語意關聯強度字對(強、弱、無關語意)。在語意判斷作業中,受試者判斷視覺呈現的中文字對是否具有語意關係。結果:行為實驗一a的反應數據顯示,隨著語意關聯強度減弱,自閉症與正常發展兩組參與者的正確率都隨之下降,所需要的反應時間也都隨之增加。然而,自閉症組在強語意相關與弱語意相關的判斷表現,相對於正常發展組都呈現較長的反應時間。行為實驗一b的反應數據顯示,自閉症組的溝通障礙症狀較嚴重者,相較於自閉症組的溝通障礙症狀較輕者,在強語意相關與弱語意相關的判斷表現,都呈現較長的反應時間。實驗二腦造影的結果顯示,相較於正常發展組,自閉症組在處理語意相關的字對時,左腦半球額下迴(left Inferior frontal gyrus, left IFG, BA 45, 47)的活化較少。更重要的發現,自閉症組在右腦半球額下迴 (right IFG, BA 47) 的神經活動,隨著溝通症狀愈嚴重,包含在自閉症診斷會談量表(Autism Diagnosis Interview-Revised, ADI-R)中溝通障礙的分數愈高,或在社會性溝通問卷(Social Communication Questionnaire, SCQ)中溝通、社會互動、及重複性行為的症狀分數愈高,此腦區的活化強度愈大,亦即自閉症症狀的嚴重程度與右額下迴的神經活動呈現正相關。結論:由本研究結果推論自閉症患童與青少年之語意處理歷程,與正常發展兒童和青少年不同。一、自閉症患者在搜尋和整合相關的語意特徵時,相較於正常發展組產生較多的困難。二、由於溝通能力涉及語意的處理歷程,溝通症狀較嚴重的自閉症患者,相較臨床溝通症狀輕的患者,在語意判斷測驗的表現較差。三、從神經生理的研究發現,自閉症組在左腦額下迴活化較正常發展組來得低,推論自閉症組較難有效地掌握提取語意相關特徵。四、自閉症組雖然在左額下迴的活化較正常發展組來得少,但是自閉症組在右額下迴的活化,隨著臨床症狀愈嚴重而產生活化愈大的現象,推論右側對應腦區表現了對於語意提取的補償機制,使自閉症患童和青少年仍能完成此項認知作業的要求。

並列摘要


Purpose: According to the DSM-IV and ICD-10 diagnosis criteria, there are three core symptoms of Autistic Spectrum Disorders (ASD) including impairments in social reciprocity, communication deficits, and repetitive/stereotyped behaviors. The present study aimed to explore the underlying mechanism of communication deficits in children and adolescents with ASD by examining their Chinese semantic judgment and brain activity related to language circuitry, and the association between language-related cognitive function and brain activity. Methods: Behavioral paradigm and functional magnetic resonance imaging (fMRI) were used to assess 8- to 18-year-old children and adolescents with clinical diagnosis of ASD and age-, sex- and IQ-matched typically developing (TD) children and adolescents (the ASD group vs. the TD group for Experiment 1a; the ASD group with a more severe communication deficit vs. the ASD group with a less severe communication deficit for Experiment 1b; the ASD group vs. the TD group for Experiment 2). The parents reported about their children with ASD by using the Autism Diagnostic Interview-Revised (ADI-R) and the Social Communication Questionnaire (SCQ). Three kinds of Chinese semantic association task with varied strength of association (stronger, weaker, and unrelated) were used. Participants were asked to determine whether visually presented character pair was related in meaning. Results: In Experiment 1a, lower accuracy and longer reaction times were found for weaker association, as compared to stronger association, in both groups. However, the ASD group responded significantly slower to both stronger and weaker association as compared with the TD group. In Experiment 1b, the ASD group with a more severe communication deficit responded significantly slower to both stronger and weaker association relative to those with a less severe communication deficit. In Experiment 2, the ASD group showed reduced activation in left inferior frontal gyrus (IFG, BA 45, 47) as compared with the TD group during semantic processing. Most importantly, for the ASD group, greater activation in right inferior frontal gyrus (IFG, BA 47) was correlated with the severity of clinical syndrome, including the communication measures in the Autism Diagnostic Interview-Revised (ADI-R) interview, and the three ASD cores syndromes in the Social Communication Questionnaire (SCQ). Conclusion: Compared with the TD group, the ASD group performed differently during semantic processing. First, the ASD group showed more difficulties in searching and unifying appropriate semantic features as compared with the TD group. Second, as communication process is related to semantic processing, the ASD group with a more severe communication deficit performed semantic judgments less efficiently relative to those with a less severe communication deficit. Third, the ASD group showed reduced activation in left IFG as compared with the TD group, implying that the ASD group may have a poorer ability in inhibition of irrelevant semantic features and in retrieval/selection of proper semantic features. Fourth, greater activation in right IFG was correlated with the severity of the ASD symptoms, implying that right IFG may play a role in a compensatory mechanism to help the children and adolescents with ASD to meet the demands of semantic judgments for the ASD group.

並列關鍵字

Autism semantic association strength fMRI ADI-R SCQ

參考文獻


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