Dynamic Functional Synchronization Profiles in Autism Differ by Spatial Scale and Along Hierarchical Cortical Gradients.

Background: Prevailing theories propose that autism is characterized by local cortical overconnectivity and long-range underconnectivity, but empirical evidence remains mixed. Methods: Here, we applied the turbulence dynamics framework to the ABIDE (Autism Brain Imaging Data Exchange) dataset ( Results: Autistic individuals showed increased short-range and reduced long-range functional synchronization variability over time, as well as reduced synchronization strength across all spatial scales. Synchronization also decayed more rapidly with distance and exerted weaker influence across scales in autism. These distance-specific alterations suggest that local hyperconnectivity may be associated with turbulent synchronization dynamics that fail to propagate coherently across the cortex, resulting in an overly rigid brain organization at longer distances. Mapping these effects onto the sensorimotor-association cortical gradient revealed increased variability in sensorimotor regions and decreased variability in the association cortex. Conclusions: Together, we found evidence of disturbances in functional synchronization dynamics at different spatial scales and along hierarchical brain gradients in autistic individuals. These results consolidate ideas about dynamic functional connectomic organization in autism and situate these alterations along hierarchical brain gradients that are closely linked to neurodevelopmental processes.