Children with autism rely heavily on proprioception, unlike children with other developmental motor impairments or typically developing children.
PROVIDENCE, RI—Children with autism spectrum disorder form a representation of internal models that places an unusually strong reliance on proprioception, according to research presented at the 39th National Meeting of the Child Neurology Society.
“This anomalous motor learning is specific to autism spectrum disorder, rather than a general deficit of all populations with developmental motor impairments, as children with ADHD did not generalize differently than typically developing children,” reported Stewart H. Mostofsky, MD, research scientist at the Kennedy Krieger Institute and Associate Professor of Neurology, Johns Hopkins University School of Medicine, Baltimore, and colleagues. “Our results suggest that autism-associated impairment in understanding actions of others may be a consequence of the fact that in learning to perform actions, children with autism place a greater than normal reliance on their own proprioception while discounting the visual consequences of their actions.”
The researchers analyzed 25 children with autism (mean age, 10.31), 16 with ADHD (mean age, 10.66), and 39 typically developing children (mean age, 10.82). As part of a game, each child held the handle of a robotic arm, trying to capture animals that had escaped from a zoo. An animal would appear at a target location 8 cm away; if the child reached the target in time, the animal was captured and the child was given a point.
“Analyses revealed that all groups were able to effectively adapt their arm movement,” stated Dr. Mostofsky’s group. “However, generalization patterns were markedly different. There was a significant interaction between diagnostic group and relative generalization to targets 2 and 3. Posthoc analyses revealed this difference was due to significantly greater generalization of the autism group in the intrinsic (proprioceptive) coordinate system as compared to typically developing children. In contrast, there was no significant difference in generalization between ADHD and typically developing children.”
Regression analyses revealed that among all groups, generalization in the intrinsic (proprioceptive) coordinate system (ie, to target 3) was a significant predictor of social ability, such that greater social impairment was predicted by increased force for target 3, noted Dr. Mostofsky and colleagues. “Further,” the researchers concluded, “for the children with autism, increased force for target 3 predicted impaired social interaction. In addition, increased generalization to target 3 also predicted impaired imitation ability, as assessed on a praxis examination, as well as impairment in motor control.”