Neural and Behavioral Mechanisms of Behavior Change and Adaptability: Examining the Role of Sensorimotor Integration in Autism

Background: Unusual sensory symptoms and motor deficits are highly prevalent in autism spectrum disorder (ASD). They can emerge early in the development of ASD, before the core social deficits and repetitive behaviors emerge, and their prevalence suggests that deficits in sensorimotor integration may contribute to characteristic features of ASD. Sensorimotor integration is the process through which the brain uses continuous sensory information to produce flexible patterns of behavior that support adaptation to one’s surroundings. Thus, impairments in sensorimotor integration may contribute to the development of inflexible patterns of social and nonsocial behavior that characterize ASD. We currently lack techniques to precisely measure sensorimotor integration in ASD and so lack an understanding of the role it may play in ASD.

Objectives: Our study aimed to (1) develop a method to simultaneously assess neural and behavioral function during a sensorimotor task, (2) develop measures of the adaptability of neural and behavioral output during the sensorimotor task, and (3) examine differences in neural and behavioral adaptability in persons with ASD.

Methods: We designed a stimulus-tracking task with simultaneous recording of high density EEG. Participants used a computer mouse to control an on-screen cursor. They were instructed to keep the cursor inside of a target that moved across the screen in a series of unpredictable patterns. The task consisted of two sensory conditions: (1) Visual Feedback: target and cursor were visible on the screen for the duration of the trial, (2) No Visual Feedback: target and cursor were visible at the beginning of the trial, but disappeared mid-trial, and participants were instructed to continue moving the mouse as if the target and cursor were still visible. Participants included young, right-handed adults with ASD (N=20) and an age- and gender-matched typically developing group (N=18). We analyzed group and visual feedback effects on motor performance (root mean squared error of cursor position), motor complexity (sample entropy), and neural complexity (multi-scale sample entropy).

Results: Participants show significantly greater error in task performance when visual feedback is not available (t=10.39, p<0.001). Consistent with this finding, motor complexity is significantly reduced in the absence of visual feedback (t=23.59, p<0.001), indicating more stereotyped patterns of movement when feedback is not available compared to when it is. Participants also demonstrate lower neural complexity in task-relevant scalp regions when feedback is withheld (Frontal: t=3.29, p=0.006; Occipital: t=3.07, p=0.009), paralleling the patterns of motor complexity.

Conclusions: Our results indicate that reliable sensorimotor integration and the availability of sensory feedback provide the brain with rich information with which to generate complex, adaptive motor output. In the absence of sensory feedback, the neural signal contains less information and correspondingly, the motor signal is more stereotyped and inflexible, thus this task provides a standardized, objective measure of inflexible, stereotyped behavior. Sensorimotor integration is likely disrupted in individuals with ASD resulting in less complex neural signals and consequently less complex, less adaptive behavior. Our ongoing work involves adapting our sensorimotor task into a “game-like” virtual reality environment, which allows assessment at earlier periods of development.