Novel Methods to Assess the Contribution of Sensorimotor Mechanisms to the Presence of Motor Stereotypy in Autism Spectrum Disorders

Background: The emergence of motor stereotypy is indicative of neural pathology in several neurodevelopmental and neuropsychiatric disorders including autism spectrum disorders (ASD); however, it is also present early in normative development during the transition from simple, uncontrolled movements to complex, controlled movements. Unlike in ASD, stereotypy in healthy infants begins to decrease within the first year of life and is replaced with goal-directed motor behavior. Research in normative development demonstrates the importance of sensory feedback for the development of motor complexity – as children develop the ability to integrate sensory information from the environment with motor behavior, their behavior becomes less stereotyped and more complex, allowing them to interact adaptively in the environment. This is consistent with our understanding of sensorimotor integration in the brain. Prior studies from our group have found that individuals with ASD who have motor stereotypy also have reduced motor complexity, consistent with the notion that motor stereotypy is a manifestation of low motor complexity. Additionally, individuals with ASD often present with unusual sensory symptoms suggesting that sensory processing deficits may contribute to the development of stereotyped actions.

Objectives:  To date, the contribution of motor and sensory factors to the development of stereotyped behavior has only been examined in isolation. There is a need for methods that assess the joint sensory and motor contributions to the emergence of the core features of ASD. The purpose of this study is to develop a method for objectively measuring the role of sensory feedback on motor performance in ASD at the level of both brain and behavior.

Methods: We are adapting methods from studies of normative motor development to assess the effect of sensory feedback on motor complexity in individuals with ASD and relate these metrics to concurrent neural activity. Our method involves the use of virtual reality gloves that monitor hand position in real time and provide sensory feedback in the form of vibro-tactile stimulation. Participants perform a task during which they use their index finger to track a moving stimulus on a screen. For half of the trials, participants receive online vibro-tactile feedback at the fingertip if they deviate from the stimulus, and in the other half of the trials, they do not receive vibro-tactile feedback. Performance is measured using indices of complexity of movement kinematics (via accelerometers embedded in the gloves) and neural complexity (via electroencephalography). Here, we present preliminary results from this novel approach focusing on (a) method feasibility and test-retest reliability and (b) the application of nonlinear dynamic analytic techniques to examine coupling of neural and behavioral output during this sensorimotor task.

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