Thalamic Hyperconnectivity and Functional Signatures in fMRI Connectomes of Autism Spectrum Disorder

Authors: S M Shayez karim, R S Rathore

Presentation type: Poster at SNUFA 2025 online workshop (5-6 Nov 2025)

Abstract

Synaptic rewiring plays a central role in shaping neuronal circuits during early childhood, laying the foundation for mental health and behavior later in life. In this work, we compare two trajectories of functional connectivity: (i) the typical developmental progression from healthy infants (3.7–32.6 months) to adults (25–35 yrs), and (ii) the transition from healthy infants to individuals with autism spectrum disorder (ASD; 9.3–35.2 yrs), which reflects both normal development and ASD-related alterations.

Using graph-theoretic measures of fMRI-derived connectomes, we quantified connectivity changes across brain lobes and assessed average and median percent differences. The comparisons reveal that synaptic reorganization is most pronounced within the thalamus and in its inter-lobe connections, with ASD patients showing marked thalamo-cortical hyperconnectivity. For the thalamus, the difference between ASD patients and adults reached 82.58 % (degree), 72.8 % (betweenness centrality), 17.41 % (clustering coefficient), and 10.77/15.57 % (global/local efficiency).

We also built regression models capturing normal developmental trends of functional connectivity across infants, children, adolescents, and adults. These models show a steady, linear increase in connectivity across most brain lobes, with the thalamus as an exception. In contrast, ASD data diverge significantly from these trends, marked by overconnectivity that sets them apart from typical development.

These distinct connectivity signatures hold promise as diagnostic markers for ASD. To move in this direction, we present a method capable of distinguishing ASD individuals from typically developing peers with notable accuracy and specificity.