Walking, Gross Motor Development, and Brain Functional Connectivity in Infants and Toddlers.

Infant gross motor development is vital to adaptive function and predictive of both cognitive outcomes and neurodevelopmental disorders. However, little is known about neural systems underlying the emergence of walking and general gross motor abilities. Using resting state fcMRI, we identified functional brain networks associated with walking and gross motor scores in a mixed cross-sectional and longitudinal cohort of infants at high and low risk for autism spectrum disorder, who represent a dimensionally distributed range of motor function. At age 12 months, functional connectivity of motor and default mode networks was correlated with walking, whereas dorsal attention and posterior cingulo-opercular networks were implicated at age 24 months. Analyses of general gross motor function also revealed involvement of motor and default mode networks at 12 and 24 months, with dorsal attention, cingulo-opercular, frontoparietal, and subcortical networks additionally implicated at 24 months. These findings suggest that changes in network-level brain-behavior relationships underlie the emergence and consolidation of walking and gross motor abilities in the toddler period. This initial description of network substrates of early gross motor development may inform hypotheses regarding neural systems contributing to typical and atypical motor outcomes, as well as neurodevelopmental disorders associated with motor dysfunction.

Motor impairment in sibling pairs concordant and discordant for autism spectrum disorders.

AIM: Although motor impairment is frequently observed in children with autism spectrum disorders (ASD), the manner in which these impairments aggregate in families affected by autism is unknown. We used a standardized measure of motor proficiency to objectively examine quantitative variation in motor proficiency in sibling pairs concordant and discordant for ASD. METHODS: Motor impairment of sibling pairs from 67 ASD-affected families comprising 29 concordant pairings and 48 discordant pairings were assessed using the Bruininks Oseretsky Test of Motor Proficiency, 2nd Edition, a standardized measure of motor proficiency. RESULTS: Motor skills were substantially impaired among ASD-affected children and highly correlated with autistic severity and IQ, whereas motor skills in unaffected siblings were essentially normal. Total motor composite scores of at least one standard deviation below the general population mean were seen in 83% of the affected group compared with 6% in the unaffected siblings. INTERPRETATION: Findings indicate that motor impairment constitutes a core characteristic of ASD (not necessarily an ASD endophenotype), which has distinct implications for taxonomy, diagnosis, and approaches to intervention.