title: Behavioural and neural basis of anomalous motor learning in children with autism.
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.
authors.affiliation: 1 Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, USA mkmarko@jhu.edu.
authors.forename: Mollie K
authors.initials: MK
authors.lastname: Marko
authors.affiliation: 2 Centre for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Deana
authors.initials: D
authors.lastname: Crocetti
authors.affiliation: 3 Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hulst
authors.affiliation: 4 The Motor Learning Laboratory, Department of Biomedical Engineering, Ben Gurion University of the Negev, Beersheba, Israel.
authors.forename: Opher
authors.initials: O
authors.lastname: Donchin
authors.affiliation: 1 Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Shadmehr
authors.affiliation: 2 Centre for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, Maryland, USA 5 Departments of Neurology and Psychiatry and Behavioural Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Stewart H
authors.initials: SH
authors.lastname: Mostofsky
mesh_terms: D001321:Autistic Disorder / Q000150:complications* / Q000473:pathology*; D001526:Behavioral Symptoms / Q000209:etiology*; D001921:Brain / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000209:etiology*; D016014:Linear Models; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009483:Neuropsychological Tests; D011434:Proprioception; D011597:Psychomotor Performance; D012371:Robotics; D012680:Sensitivity and Specificity
keywords: autism; cerebellum; error sensitivity; motor learning; proprioception; reaching