Oscillatory Traveling Waves During Visual Entrainment in Autistic and Non-Autistic Adults

Neural oscillations and traveling waves play a crucial role in cognition. In scalp electroencephalography (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 reflect predictive signals, whereas forward waves convey sensory processes and prediction errors. In this study, we investigated traveling wave dynamics during a visual entrainment task in non-autistic and autistic adults. Our results show an increase in backward waves during rhythmic visual stimulation in the non-autistic group, consistent with enhanced top-down predictions. Notably, we observed the opposite pattern in the autism group, characterized by a pronounced increase in forward waves at the entrained frequency (ω² = 0.132). These results align with predictive coding accounts of autistic perception, which hypothesize a difference in balance between predictions and sensory evidence. Specifically, an increase in forward waves may reflect a bias toward sensory signaling over predictive feedback, due to atypical hierarchical communication across brain regions. Together, our findings shed new light on the oscillatory dynamics involved in visual entrainment in non-autistic adults and provide novel evidence in favor of predictive coding accounts of autistic perception.Lay AbstractThe brain continuously processes information by combining incoming sensory signals with prior expectations about the environment. According to predictive coding theories, perception depends on a balance between these two processes: the brain generates predictions about what is likely to happen and then updates those predictions when incoming sensory information does not match expectations. In autism, several theories suggest that this balance may be atypical, with perception relying more strongly on sensory input and less on prior predictions. One way to study how the brain communicates during perception is through 'traveling waves', patterns of rhythmic brain activity that move across the cortex over time. These waves can be measured noninvasively using electroencephalography (EEG). In visual tasks, waves traveling from the back of the brain toward the front are generally linked to the processing of sensory information, whereas waves traveling from the front toward the back are thought to reflect top-down signals such as predictions, expectations, and attentional control. In this study, we investigated traveling brain waves in autistic and non-autistic adults during a visual entrainment task, in which participants viewed rhythmic visual stimulation. We found that non-autistic participants showed an increase in backward traveling waves during stimulation, consistent with stronger predictive or top-down processing. In contrast, autistic participants showed the opposite pattern, with a marked increase in forward traveling waves at the frequency of the visual stimulation. This suggests a greater weighting of incoming sensory signals relative to predictive feedback in autism.