Reduced anticipatory 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 pre-registered 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 target predictability on reaction 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 upcoming target prediction on the late CNV, a motor preparatory ramping potential. Anticipatory desynchronization of motor-related mu and beta oscillations differed by group, but only following tones that signaled medium target probability: the autistic group showed no desynchronization for medium probability tones, whereas the non-autistic group showed desynchronization comparable to high probability tones. We also found evidence of a group difference in neural entrainment to the 1Hz periodic sequence: the autistic group showed shallower anticipatory ramping potentials after all tones, 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.