Intra- and inter-hemispheric connectivity in lateralized brain areas associated with autism symptoms
Poster No:
1564
Submission Type:
Abstract Submission
Authors:
Junesung Yoon1, Hang Joon Jo2, Taeyeop Lee1, Yong-Wook Shin3
Institutions:
1Asan Medical Center, Seoul, Korea, Republic of, 2Hanyang University, Seoul, AK, 3Department of Psychiatry, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea, Republic of
First Author:
Co-Author(s):
Yong-Wook Shin
Department of Psychiatry, University of Ulsan College of Medicine, Asan Medical Center
Seoul, Korea, Republic of
Department of Psychiatry, University of Ulsan College of Medicine, Asan Medical Center
Seoul, Korea, Republic of
Introduction:
Brain lateralization, the functional specialization of the human brain's two hemispheres, is notably significant in autism spectrum disorder (ASD). Many studies indicate reduced lateralization in ASD, emphasizing its relevance in understanding the disorder1,2.
This study employed the novel laterality index3 to investigate the relationship between brain lateralization and autism spectrum disorder. This index consists of two components: Segregation and Integration. Segregation measures the tendency for greater within-hemisphere than across-hemisphere communication, and Integration measures a sum of within- and across-hemisphere communication. As the left hemisphere mainly engages in Segregation while the right hemisphere shows Integration3-5 , we hypothesized that intra-hemispheric functional connectivity in the left-lateralized segregation network and the inter-hemispheric functional connectivity in right-lateralized integration network are associated with symptoms of autism spectrum disorder (ASD).
This study employed the novel laterality index3 to investigate the relationship between brain lateralization and autism spectrum disorder. This index consists of two components: Segregation and Integration. Segregation measures the tendency for greater within-hemisphere than across-hemisphere communication, and Integration measures a sum of within- and across-hemisphere communication. As the left hemisphere mainly engages in Segregation while the right hemisphere shows Integration3-5 , we hypothesized that intra-hemispheric functional connectivity in the left-lateralized segregation network and the inter-hemispheric functional connectivity in right-lateralized integration network are associated with symptoms of autism spectrum disorder (ASD).
Methods:
We used rs-fMRI data from the ABIDE I and II dataset, including 127 ASD and 134 control subjects from NYU Langone Medical Center. After preprocessing with afni_proc.py in AFNI, time-series data at each node was correlated with the activity at every other node within and across hemispheres, averaging these correlations separately per location to quantify intra- and inter-hemispheric cortical interactions. Thus, each node was assigned with two values: left hemispheres with LL (meaning average correlation of the "left" hemisphere seed node with every node in "left" hemisphere as target nodes) and LR, and right hemispheres with RR and RL. Segregation was computed as LL-LR (left) and RR-RL (right), while Integration was calculated as LL+LR (left) and RR+RL (right).
To identify networks of interest, paired t-tests were applied separately to the segregation and integration metrics across participants. By clustering brain regions with significantly greater laterality index than their homotopic locations, we identified left-lateralized segregation networks and right-lateralized integration networks (Fig.1).
For each ASD subject, we calculated the average LL score to quantify functional intra-hemispheric interaction in the left-lateralized regions. We also calculated the average RL score for the right-lateralized regions to measure inter-hemispheric connections. To examine relationships between patterns of intra- and inter-hemispheric connectivity and autism symptom severity, the Pearson correlation between ADOS scores and these averaged scores was calculated.
To identify networks of interest, paired t-tests were applied separately to the segregation and integration metrics across participants. By clustering brain regions with significantly greater laterality index than their homotopic locations, we identified left-lateralized segregation networks and right-lateralized integration networks (Fig.1).
For each ASD subject, we calculated the average LL score to quantify functional intra-hemispheric interaction in the left-lateralized regions. We also calculated the average RL score for the right-lateralized regions to measure inter-hemispheric connections. To examine relationships between patterns of intra- and inter-hemispheric connectivity and autism symptom severity, the Pearson correlation between ADOS scores and these averaged scores was calculated.
Results:
The averaged LL and RL scores in the networks of interest showed a statistically significant correlation with the ADOS scores (Fig. 2). To illustrate, averaged LL score in the left-lateralized regions were found to be negatively correlated with ADOS total score (r=-0.307, P=0.0014), ADOS social interaction score (r=-0.309, P = 0.0012) and ADOS communication score (r=-0.2573, P=0.008), but not with ADOS restricted and repetitive behavior score (r=0.0557, P=0.5723). In addition, averaged RL score in the right-lateralized regions showed negative correlation with ADOS total score (r=-0.3247, P=0.0007), ADOS social interaction score (r=-0.3162, P=0.001) and ADOS communication score (r=-0.2781, P=0.004) but no significant correlation with ADOS restricted and repetitive behavior score (r=0.0332, P=0.7371).
Conclusions:
In conclusion, our results suggest that functional intra-hemispheric connectivity in left lateralized brain regions and inter-hemispheric connectivity in right lateralized brain regions are negatively correlated with ADOS total score, social interaction score, and communication score. Our study highlights the complex relationship between functional brain connectivity in lateralized brain areas and ASD symptom severity, particularly how different patterns of left and right hemispheres correlate with ASD symptoms.
Disorders of the Nervous System:
Neurodevelopmental/ Early Life (eg. ADHD, autism) 2
Modeling and Analysis Methods:
Connectivity (eg. functional, effective, structural) 1
Keywords:
Autism
FUNCTIONAL MRI
Hemispheric Specialization
1|2Indicates the priority used for review
Provide references using author date format
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