Motor synergies: Evidence for a novel motor signature in autism spectrum disorder

• Main Authors: Boni, S. (Author), D'Ausilio, A. (Author), Emanuele, M. (Author), Fadiga, L. (Author), Marini, M. (Author), Nazzaro, G. (Author), Polletta, G. (Author), Veronesi, C. (Author)
• Format: Article
• Language: English
• Published: Elsevier B.V. 2021
• Subjects: Article; autism; Autism spectrum disorder; Autism Spectrum Disorder; Biomechanical Phenomena; biomechanics; child; Child; classification algorithm; clinical article; clinical study; Communication; controlled study; degree of freedom; demography; diagnostic accuracy; diagnostic test accuracy study; DSM-5; Early diagnosis; female; hand strength; Hand Strength; handedness; human; Humans; ICD-10; interpersonal communication; Kinematics; language ability; Machine learning; male; motor control; motor coordination; Motor synergies; movement time; Neurodevelopmental disorders; preschool child; receiver operating characteristic; social behavior; Social Behavior; social interaction
• Online Access: View Fulltext in Publisher

 In autism spectrum disorder (ASD), socio-communicative impairments and stereotypical behaviours are paralleled by sensorimotor deficits. Individuals with ASD show an altered selection of motor parameters, resulting in clumsy and fragmented actions. Here, we investigated inter-joint coordination and motor synergies as a potential substrate of motor control problems in ASD. Synergies enable co-controlling redundant motor degrees of freedom (DoF, e.g. joint angles, muscles) by mapping behavioural goals into a flexible and low-dimensional set of variables. This mechanism simplifies motor control and helps to find unambiguous solutions for motor tasks. In a reaching-grasping paradigm, children with ASD showed reduced coupling between DoF, which correlated with socio-communicative symptoms severity. Impaired synergies may help to frame well-established motor problems in ASD, including impaired motor sequencing and abnormal trial-to-trial motor variability. On the other hand, synergies also provide an effective and compact coding system of observed actions. Impaired synergies may thus jeopardize motor interaction by initiating bottom-up cascade effects, leading to pervasive impairments of social behaviour. Finally, we trained an automatic classification algorithm to distinguish between ASD and typically developing (TD) participants based on reaching-grasping kinematics. Classification accuracy reached up to 0.947. This result corroborates and expands previous accounts claiming that motor-based early recognition is feasible and effective in ASD. © 2021