Reduced Motor Preparation and Altered EEG Signatures of Prediction in Autistic Adults.

A standing hypothesis proposes that the social and behavioral diagnostic features of autism may develop as a result of more fundamental difficulties in forming and utilizing predictions. More specifically, in the present study, we hypothesized that autistic individuals are less likely to mobilize motor preparatory processes when given reason to anticipate an imperative cue. In a preregistered experiment, we asked participants to respond as quickly as possible to target sounds embedded in a regular periodic sequence of tones, and informed them that the three distinct auditory tones in the sequence signal different probabilities of a target on the next beat. We found that a group of autistic participants showed significantly less benefit of cues signaling high target probability on target response time than an IQ- and language-matched control group of non-autistic participants. In concurrent electroencephalography (EEG) recordings, the autistic group also showed a reduced effect of high probability cues on the late CNV, a motor preparatory ramping potential. Group differences in anticipatory desynchronization of motor-related mu and beta oscillations were less straightforward-rather than showing broadly weaker predictive desynchronization, the autistic group showed reduced desynchronization specifically following medium probability cues. We also found evidence of a group difference in neural entrainment to the 1 Hz periodic sequence: the autistic group showed shallower ramping potentials anticipating the next event across all cue types, and reduced phase entrainment at posterior electrodes. Our results focus attention on reduced spontaneous predictive motor preparation as a possible sensorimotor contribution to autism's more visible manifestations.