Poster E55, Saturday, August 18, 3:00 – 4:45 pm, Room 2000AB

Developmental changes in neural connectivity of semantic processing in youths with autism and typically developing youths

Min Liu1, Susan Shur-Fen Gau1,2,3,4, Tai-Li Chou1,3,4;1Department of Psychology, National Taiwan University, Taipei, Taiwan, 2Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan, 3Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan, 4Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan

Youths with autism spectrum disorders (ASD) and typically developing (TD) youths have shown differential meaning processing and brain activation. Youths with ASD rely more on lower-level visual processing during semantic judgments, which is related to greater activation in the cuneus. In contrast, TD youths engage more in the higher-level processing of retrieving or selecting semantic features, which is related to greater activation in the inferior frontal gyrus (IFG). However, it is not known how functional connectivity with these regions changes between TD and ASD youths, and whether differential functional connectivity is age-dependent. The present study thus aimed to explore age-dependent functional connectivity of semantic processing in TD and ASD youths. The participants were divided into the ASD and TD groups, with each group divided into two age groups (child, adolescent). They were asked to judge whether written word pairs were related in meaning within an MRI scanner. The psychophysiological interaction (PPI) analysis was conducted to explore functional connectivity that examined dynamic interaction between brain regions. There were three major findings. First, for the ASD children, two significant connections were found between the inferior frontal gyrus (IFG) and right inferior parietal lobule (IPL) and between the cuneus and right IPL, which suggests a visual-based processing during semantic judgments. Second, for the TD children, a significant connection was found between the cuneus and middle temple gyrus (MTG), which suggests a direct mapping between orthography and semantic representations during semantic judgments. Third, for the TD adolescents, a significant connection was found between the IFG and MTG, suggesting more elaborate semantic representations that require greater engagement of selection processes in the TD adolescents. In conclusion, our results imply different patterns of functional connectivity during semantic processing between ASD and TD youths. The ASD children may rely on visual/perceptual processing to meet the demands of the semantic task. The TD children may rely on bottom-up visual information to access semantic knowledge, whereas the TD adolescents may use a top-down controlled process to retrieve semantic knowledge. Keywords:semantic; functional connectivity; age; fMRI

Topic Area: Language Development

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