Dynamic functional synchronization profiles in autism differ by spatial scale and along hierarchical cortical gradients

Although prevailing theories propose that autism is characterized by local cortical overconnectivity and long-range underconnectivity, the supporting empirical evidence has been mixed. Here we demonstrate that these divergent findings can be reconciled by examining how functional synchronization profiles dynamically change over time and across the cortex over different spatial scales. We applied the turbulence dynamics framework to the ABIDE dataset (n = 1,009) and found evidence for altered functional synchronization dynamics in autism. 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 generate turbulent, chaotic 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. Together, we found evidence of disturbances in functional synchronization dynamics at different spatial scales and along hierarchical brain gradients in individuals with autism. These results help consolidate ideas about how dynamic functional connectomic organization manifests in autism and pinpoints likely early neurodevelopmental effects along a primary axis of hierarchical cortical organization.