| Summary: | 碩士 === 國立臺灣大學 === 心理學研究所 === 102 === Introduction：Social-communication is one of the core symptoms in the DSM-5 diagnostic criteria for autism spectrum disorder (ASD). One of the characteristics of communication deficits in ASD is impaired comprehension. However, little is known about the involvement of social deficits on semantic processing in ASD. This study aims to explore the neural substrates of interaction between social ability and semantic processing in youths with ASD as compared to typically developing youths. Methods：Functional magnetic resonance imaging was used to assess 55 youths with ASD (age range: 9-18) and 29 typically developing youths (age mean = 12.48, SD = 2.75). The ASD group was divided into the mild (n = 27, age mean = 13.09, SD = 2.23) and severe (n = 28, age mean = 13.85, SD = 2.65) groups according to their current scores of the reciprocal social interaction on the Autism Diagnostic Interview-Revised. The three groups were matched in age, gender, IQ, and handedness. Participants were asked to judge if two Chinese characters were related in meaning, and the brain activations between groups were compared. Additionally, the magnitudes of brain activations were correlated with the Social Responsiveness Scale (SRS) and the picture completion scores. Results：Compared to typically developing youths, both ASD groups showed reduced activations in left anterior insula cortex (AIC), inferior frontal gyrus (IFG), and middle temporal gyrus (MTG). There were negative correlations between AIC/IFG/MTG activations and SRS scores across groups. In contrast, the severe ASD group showed greater activations in left cuneus relative to the typically developing group. There was a positive correlation between the intensity of cuneus activation and the score of picture completion across mild and severe ASD groups. Conclusion：Our findings imply an association between social deficits and impaired semantic processing in youths with ASD. Reduced activations in the AIC、IFG and MTG associated with the severity of social deficits in youths with ASD highlight their difficulty in integrating social information with meaning and their decreased reliance on semantic information, respectively, as compared to typically developing youths. Our finding of a positive correlation between left cuneus activation and the score of picture completion across ASD groups suggests that regardless of severity of social deficits they tend to rely more on lower-level visual information to process Chinese characters.
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