Motor Skill Learning in Autism

Principal Investigator: Stewart Mostofsky

Abnormalities on motor examination have often afforded valuable insights into developmental disorders of the brain; such abnormalities have been well documented in individuals with autism and, in fact, date back to some of the original descriptions of the disorder. Increased insight into the brain mechanisms underlying autism can be gained from careful consideration of these motor signs. By using tests of motor function for which the neurologic basis is well mapped out, it is possible to gain an understanding of the neural circuits impaired in autism; motor signs can also serve as markers for parallel deficits in brain systems important for control of the social and communication skill impairments that characterize autism. One of the most consistently observed abnormalities on motor examination of autistic patients are associated deficits in performance of complex gestures, including those involving motor imitation, and in performance of skilled motor tasks.

In the context of the developmental disorder of autism, these motor skill deficits could be secondary to a fundamental problem with acquiring motor skills, i.e. motor skill learning. The overall goal of this project is to better characterize motor learning deficits in autism, to examine the association of motor learning deficits with observed abnormalities in performance of skilled motor tasks/gestures (including imitation) and sensory processing, and to investigate the brain abnormalities associated with these deficits using functional magnetic resonance imaging (fMRI). Furthermore, a large component of social interaction and communication involves the execution of a series of “learned” gestures and complex movements (e.g., waving good-bye, blowing a kiss, offering comfort to someone). Impaired learning of motor and other skills (referred to as “procedural learning”) could help to explain the core social and communicative deficits of autism; we will begin to investigate the contribution of procedural learning to language development using a test of mental grammar.

Aim 1: To characterize patterns of motor learning deficits in children with autism and examine the hypothesis that children with autism will show impaired performance on motor adaptation and motor sequence learning tasks in which motor learning is guided by visual feedback.

Aim 2: To investigate the hypothesis that in children with autism, deficits in performance of skilled motor tasks/gestures are secondary to a fundamental problem with motor skill learning. We hypothesize that children with autism will show impaired ability to perform complex motor skills and
gestures, and that children’s ability to execute these motor skills/gestures will be predicted by performance on tests of visual-motor skill learning.

Aim 3: To test the hypothesis that in autism, impairments in procedural learning contribute to deficits in mental grammar of rules used to generate additional grammatical forms of words as well as combine words into phrases and sentences. Compared with controls, children with autism are predicted to show deficits in the application of grammatical skills (rules), as demonstrated by difficulty using regular word transformations (which requires the application of a grammatical rule; e.g., look-looked).

Aim 4: To examine, using fMRI, the hypothesis that children with autism will show differences in patterns of activation during performance of visual-motor sequence learning and adaptation tasks. Differences will include decreased activation in posterior and inferior regions of the cerebellum, with increased activation in other regions, including the anterior cerebellum.

Aim 5: To examine sensory processing in children with autism in comparison to that in typically developing children (TD) as assessed by performance-based measures of sensory perception/processing and formal parent-report.