Structural filtering of functional data offered discriminative features for autism spectrum disorder

This study attempted to answer the question, Can filtering the functional data through the frequency bands of the structural graph provide data with valuable features which are not valuable in unfiltered data?. The valuable features discriminate between autism spectrum disorder (ASD) and typically control (TC) groups. The resting-state fMRI data was passed through the structural graph's low, middle, and high-frequency band (LFB, MFB, and HFB) filters to answer the posed question. The structural graph was computed using the diffusion tensor imaging data. Then, the global metrics of functional graphs and metrics of functional triadic interactions were computed for filtered and unfiltered rfMRI data. Compared to TCs, ASDs had significantly higher clustering coefficients in the MFB, higher efficiencies and strengths in the MFB and HFB, and lower small-world propensity in the HFB. These results show over-connectivity, more global integration, and decreased local specialization in ASDs compared to TCs. Triadic analysis showed that the numbers of unbalanced triads were significantly lower for ASDs in the MFB. This finding may indicate the reason for restricted and repetitive behavior in ASDs. Also, in the MFB and HFB, the numbers of balanced triads and the energies of triadic interactions were significantly higher and lower for ASDs, respectively. These findings may reflect the disruption of the optimum balance between functional integration and specialization. There was no significant difference between ASDs and TCs when using the unfiltered data. All of these results demonstrated that significant differences between ASDs and TCs existed in the MFB and HFB of the structural graph when analyzing the global metrics of the functional graph and triadic interaction metrics. Also, these results demonstrated that frequency bands of the structural graph could offer significant findings which were not found in the unfiltered data. In conclusion, the results demonstrated the promising perspective of using structural graph frequency bands for attaining discriminative features and new knowledge, especially in the case of ASD.

Automated summary

This study explored the use of frequency bands in the structural graph to filter functional data and found significant differences between the autism spectrum disorder (ASD) group and the typically control (TC) group in the middle frequency band (MFB) and high frequency band (HFB). The results showed that ASDs had higher clustering coefficients, efficiencies, and strengths, as well as lower small-world propensity, indicating over-connectivity, more global integration, and decreased local specialization compared to TCs. Triadic analysis revealed that ASDs had fewer unbalanced triads and more balanced triads in the MFB, suggesting a potential link to restricted and repetitive behavior in ASDs. Additionally, the energies of triadic interactions were significantly lower for ASDs in the MFB and HFB, possibly indicating a disruption of the balance between functional integration and specialization. These results highlight the importance of analyzing the global metrics of functional graphs and triadic interaction metrics using frequency bands of the structural graph.