Characteristics of Brains in Autism Spectrum Disorder: Structure, Function and Connectivity across the Lifespan

Autism spectrum disorder (ASD) is a highly prevalent neurodevelopmental disorder characterized by impaired social communication and restricted and repetitive behaviors (RRBs). Over the past decade, neuroimaging studies have provided considerable insights underlying neurobiological mechanisms of ASD. In this review, we introduce recent findings from brain imaging studies to characterize the brains of ASD across the human lifespan. Results of structural Magnetic Resonance Imaging (MRI) studies dealing with total brain volume, regional brain structure and cortical area are summarized. Using task-based functional MRI (fMRI), many studies have shown dysfunctional activation in critical areas of social communication and RRBs. We also describe several data to show abnormal connectivity in the ASD brains. Finally, we suggest the possible strategies to study ASD brains in the future.

Abnormal Brain Activity in Social Reward Learning in Children with Autism Spectrum Disorder: An fMRI Study

PURPOSE: We aimed to determine whether Autism Spectrum Disorder (ASD) would show neural abnormality of the social reward system using functional MRI (fMRI). MATERIALS AND METHODS: 27 ASDs and 12 typically developing controls (TDCs) participated in this study. The social reward task was developed, and all participants performed the task during fMRI scanning. RESULTS: ASDs and TDCs with a social reward learning effect were selected on the basis of behavior data. We found significant differences in brain activation between the ASDs and TDCs showing a social reward learning effect. Compared with the TDCs, the ASDs showed reduced activity in the right dorsolateral prefrontal cortex, right orbitofrontal cortex, right parietal lobe, and occipital lobe; however, they showed increased activity in the right parahippocampal gyrus and superior temporal gyrus. CONCLUSION: These findings suggest that there might be neural abnormality of the social reward learning system of ASDs. Although this study has several potential limitations, it presents novel findings in the different neural mechanisms of social reward learning in children with ASD and a possible useful biomarker of high-functioning ASDs.

Correction / 대한내과학회지

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A longitudinal study on the relationship between methacholine airway hyperresponsiveness and exercise-induced bronchoconstriction / 대한내과학회지

BACKGROUND/AIMS: The airway hyperresponsiveness (AHR) in asthma has variable and persistent components that are related to airway inflammation and remodeling, respectively. This longitudinal study examined the relationship of airway responses between exercise (reflecting variable AHR) and methacholine (reflecting persistent AHR). METHODS: The charts were reviewed of 36 young adult males who underwent both methacholine and exercise challenges at different times and were diagnosed with exercise-induced asthma. The severity of the response to each stimulus was scored (0~3). RESULTS: The mean interval between the baseline and follow-up tests was 9.8 (5~58) months. The AHR score was significantly lower with the exercise challenge than with methacholine at follow-up (1.58+/-0.16 vs 1.19+/-0.15, p<0.01), but not at baseline. Compared to baseline, the AHR score was significantly lower with exercise (1.67+/-0.13 vs 1.19+/-0.15, p<0.01), but not with methacholine, and the difference in the AHR scores between exercise and methacholine increased significantly from baseline to follow-up (0.03+/-0.13 vs 0.39+/-0.13, p<0.05). The maximum fall in the forced expiratory volume in 1 s following exercise was significantly related to methacholine AHR (r=-0.571, p<0.001). CONCLUSIONS: Exercise-induced bronchoconstriction was significantly related to methacholine AHR. However, the change in methacholine AHR in a follow-up test was significantly lower than that in the exercise response, which might have resulted from persistent worsening of the AHR with time because methacholine AHR reflects both variable and persistent AHR.