Oscillatory traveling waves during visual entrainment in autistic and neurotypical adults

Abstract

Neural oscillations play a crucial role in cognition, and several studies emphasize the importance of considering them as traveling waves that propagate through brain regions. In scalp EEG, waves typically travel along the anterior-posterior axis: forward waves (occipital-to-frontal) predominate during sensory stimulation, while backward waves (frontal-to-occipital) emerge during rest and top-down modulation. Within the predictive coding framework, backward waves are proposed to convey predictive signals, whereas forward waves reflect sensory processes and feedforward propagation of prediction errors. In this study, we investigated traveling wave dynamics during a visual entrainment task in neurotypical (N=25) and autistic (Autism Spectrum Disorder - ASD) adults (N=24). Our results replicated previous findings in neurotypical participants, as we observed an increase in backward waves during rhythmic visual stimulation, consistent with enhanced top-down predictions. Notably, we observed the opposite pattern in the ASD group, characterized by a pronounced increase in forward waves at the entrained frequency during visual stimulation. These results align with predictive coding accounts of autistic perception, which hypothesize an imbalance between predictions and sensory evidence. Specifically, an increase in forward wave may reflect a bias toward bottom-up sensory signaling over predictive feedback, due to atypical hierarchical communication across brain regions in ASD. Together, our findings shed new light on the oscillatory dynamics involved in visual entrainment in neurotypical adults and provide novel evidence in favor of predictive coding accounts of autistic perception, as well as a consequent bias toward bottom-up sensory signaling over predictive feedback in a context of visual entrainment. Significance statementTraveling waves reflect the spatiotemporal propagation of neural oscillations, providing a window into hierarchical brain communication. By examining traveling wave dynamics during visual entrainment, we show that neurotypical adults exhibit increased backward (frontal-to-occipital) waves, consistent with enhanced top-down predictive signaling. In contrast, adults with Autism Spectrum Disorder (ASD) display a marked increase in forward (occipital-to-frontal) waves, indicating stronger bottom-up sensory drive. These findings provide electrophysiological evidence for atypical predictive processing in ASD, supporting predictive coding theories that propose an imbalance between sensory evidence and prior expectations. Our results highlight traveling waves as a sensitive neural marker of hierarchical signaling and predictive dynamics across typical and atypical perceptual systems.