Behavioural and neural basis of anomalous motor learning in children with autism

TLDR

Autism spectrum disorder is marked by social and communication deficits and motor impairments, and motor learning is known to rely on the anterior cerebellum. The study aims to quantify motor learning in ASD and examine its neural basis in the cerebellum. Twenty children with ASD and twenty controls performed reaching movements with a robotic manipulandum that introduced random perturbations, allowing the study of error‑based learning from visual and proprioceptive cues. ASD children showed enhanced proprioceptive error learning but impaired visual error learning, and their smaller anterior cerebellum—particularly lobules VI and VIII—correlated with these altered learning patterns.

Abstract

Autism spectrum disorder is a developmental disorder characterized by deficits in social and communication skills and repetitive and stereotyped interests and behaviours. Although not part of the diagnostic criteria, individuals with autism experience a host of motor impairments, potentially due to abnormalities in how they learn motor control throughout development. Here, we used behavioural techniques to quantify motor learning in autism spectrum disorder, and structural brain imaging to investigate the neural basis of that learning in the cerebellum. Twenty children with autism spectrum disorder and 20 typically developing control subjects, aged 8–12, made reaching movements while holding the handle of a robotic manipulandum. In random trials the reach was perturbed, resulting in errors that were sensed through vision and proprioception. The brain learned from these errors and altered the motor commands on the subsequent reach. We measured learning from error as a function of the sensory modality of that error, and found that children with autism spectrum disorder outperformed typically developing children when learning from errors that were sensed through proprioception, but underperformed typically developing children when learning from errors that were sensed through vision. Previous work had shown that this learning depends on the integrity of a region in the anterior cerebellum. Here we found that the anterior cerebellum, extending into lobule VI, and parts of lobule VIII were smaller than normal in children with autism spectrum disorder, with a volume that was predicted by the pattern of learning from visual and proprioceptive errors. We suggest that the abnormal patterns of motor learning in children with autism spectrum disorder, showing an increased sensitivity to proprioceptive error and a decreased sensitivity to visual error, may be associated with abnormalities in the cerebellum.