Different Neural Mechanisms of Semantic Processing Among Youths with Autism Spectrum Disorder, their Unaffected Siblings and Typically Developing Youths

• Main Authors: Chuan-Ching Liao, 廖專晶
• Other Authors: Tai-Li Chou
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/6upj59

碩士 === 國立臺灣大學 === 心理學研究所 === 107 === Autism spectrum disorder (ASD) is characterized as a highly heritable disorder, and aberrant semantic processing is one of common symptoms in individuals with ASD. Unaffected ASD siblings usually have similar genetic backgrounds and early-life environments with individuals with ASD, with a higher risk of developing the same disorder. However, little is known about genetic contributions to neural mechanisms of semantic processing in unaffected ASD siblings. Therefore, this study aimed to adopt an endophenotype approach to investigate the differences in underlying neural mechanisms of semantic processing in youths with ASD, their unaffected siblings, and typically developing (TD) youths. Endophenotypes for ASD were defined as similarly heritable traits that were correlated with ASD. This study recruited 39 ASD youths (mean age = 14.8 years, standard deviation [SD] = 3.9 years), their unaffected siblings (mean age = 15.7 years, SD= 5.2 years), and 40 TD youths (mean age = 14.6 years, SD= 4.7 years). These three groups of participants were matched with IQ, age, and handedness. Participants were instructed to judge whether two Chinese characters were related in meaning in an MRI scanner. Our behavioral result showed that there were no significant differences on accuracy and reaction time among these three groups. Brain imaging data revealed that unaffected siblings and TD youths showed greater brain activation in the left MTG as compared with ASD youths. Moreover, the unaffected siblings and ASD youths showed greater cuneus activation as compared to TD youths. Furthermore, unaffected siblings showed intermediate left IFG activation between TD and ASD youths, with the strongest activation in TD youths and the weakest in ASD youths. Our findings provided a supportive evidence that abnormal neural activation in the left IFG and the cuneus during semantic processing could serve as an endophenotype of ASD. For our unaffected ASD siblings, they may have intact lexical representation system as TD youths; however, because of shared genetic features with ASD, they adpoted the same perception-based strategies as ASD youths, and may have rather immature ability to manipulate semantic representations.