A Novel Framework for Impaired Imitation in ASD

Overview

There is long-standing recognition that people with autism spectrum disorders (ASD) have difficulty imitating others' actions; some investigators have highlighted impaired imitation as being a core contributor to the development of autism. What is yet unknown is precisely how imitation in children with ASD differs from that of typically developing peers.The investigators have identified a task parameter that separates preserved from impaired gesture imitation in ASD: children with ASD have difficulty imitating when the task requires two separate movement elements be coordinated simultaneously. By contrast, imitation is relatively preserved when movement elements are performed serially. The coordination of simultaneous movements is a hallmark of actions performed in the real world. With an eye to optimizing common therapies that depend heavily on imitation, the next step is to tease apart where, in the chain from perception to action, the capacity limitation in simultaneous processing lies. This study will be conducted in about two days and will involve imitating gestures that are presented via video. In addition, an EEG will record the brain's electrical activity during certain tasks to assess how the brain responds when the imitation task is more or less difficult. Several other clinical and behavioral measures will also be used.

Visuo-motor imitation (VMI) impairments are central to the pathogenesis and affect the treatment of autism spectrum disorders (ASD). Therapies most commonly used to enhance social, communicative, academic, adaptive and occupational function in individuals with ASD rely on imitation, and impairments in VMI represent a bottleneck to the efficiency and efficacy of these therapies. Furthermore, an influential psychological account suggests that imitation impairments lead to the development of the ASD phenotype. By studying precisely how VMI is impaired in ASD, it is possible both to enhance widespread therapies and possibly to alter the course of the disorder itself. Unfortunately, researchers currently know little about the precise nature of imitation impairments in ASD. Our laboratory has recently identified a promising specific task parameter that separates preserved from impaired gesture imitation in ASD: children with ASD have difficulty imitating when the task requires two separate movement elements be coordinated simultaneously. By contrast, imitation is relatively preserved when movement elements are performed serially. This finding has been subsequently validated in a published study and again replicated in preliminary data. Coordination of simultaneous movements is a hallmark of skills performed in the real world (shoe tying, eating with knife-and-fork, driving, communicating with simultaneous verbal and gestural language). In order to optimize common adaptive and social-communicative skill therapies, the next step is to tease apart where, in the chain from perception to action, the capacity limitation in simultaneous processing lies. To do this, the investigators propose a rigorous research plan that encompasses three complementary experimental approaches: systematic psychophysics, neuropsychological testing and EEG. The goal is to specifically dissect the contribution to the simultaneity bottleneck in perceptual vs. motor processes using psychophysical control experiments. Under the hypothesis that some children with ASD may have more perceptual limitations and others may have more motor limitations, the investigators will assess heterogeneity explicitly. It is then possible to relate perceptual and motor aspects of simultaneous gesture VMI to validated neuropsychological tests of known clinical attentional and perceptual deficits in ASD. Finally, in Aim 3, the investigators will directly interrogate visual and motor networks. EEG measures of task-related activation are sensitive to task load and can be differentially assessed in visual and motor networks. By assessing deficient event-related modulation of EEG activity in visual or motor networks to simultaneous (high-load) vs. serial (low-load) conditions, the investigators can pinpoint the bottleneck. In addition to providing an approach that is complementary to the behavioral measures of Aims 1 and 2, the results of the EEG study can pave the way for future biomarkers and neurostimulation therapies.