Not Just Noise: Impaired Oscillatory Entrainment Reflects Reduced Temporal Flexibility in Autism
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Rhythmic patterns in the environment enhance neural activity, perception, and action. However, natural rhythms are often imprecise, requiring flexible adaptation. In autism Spectrum Disorder (ASD), characterized by cognitive rigidity and atypical use of prior information - favoring immediate sensory input over predictive cues - entrainment to temporally variable input may be reduced at both neural and behavioral levels, though the neural mechanisms remain unclear. Here, we recorded high-density EEG and behavior in adults with ASD (n=20) and neurotypical (NT) controls (n=21) during a visual detection task with four rhythmic structures, parametrically varied from an isochronous fully regular rhythm, to a highly irregular one. Spectral analysis and temporal response function (TRF) models revealed significantly reduced modulation by temporal regularity in ASD, particularly in mildly jittered stimulation streams. Additionally, the coupling between phases of neural oscillations and behavior was diminished in ASD under the jittered conditions, suggesting reduced functional relevance of neural synchronization. Residual spectral power post-stimulation showed lower oscillatory entrainment in ASD, ruling out simple evoked-response explanations. Notably, the degree of neural modulation by temporal regularity was correlated with IQ within the ASD group, suggesting a link between temporal flexibility and individual cognitive profiles. These findings highlight impaired neural entrainment and reduced behavioral modulation by temporal structure in ASD, offering insight into inflexible responses to uncertain, volatile sensory environments.
Innovation
Entrainment to rhythmic events is reduced in autism, but it remains unclear whether this reflects a general, non-selective deficit in neuro-oscillatory alignment or a selective vulnerability to volatile temporal structures, such as those with embedded jitter. To address this, we recorded cortical activity and behavioral performance as participants with ASD engaged with visual sequences of varying rhythmic regularity, and examined how temporal predictability modulated oscillatory entrainment. By correlating neural entrainment with target detection and clinical profiles, we sought to uncover a key feature of the autistic phenotype: reduced temporal flexibility in adapting to unpredictable sensory environments.
