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Title page for ETD etd-05012019-111407

Type of Document Dissertation
Author Shafer, Robin Lynn
Author's Email Address robin.l.shafer@vanderbilt.edu
URN etd-05012019-111407
Title Movement Kinematic and Electrophysiological Signatures of Sensorimotor Integration in Autism
Degree PhD
Department Neuroscience
Advisory Committee
Advisor Name Title
Carrisa Cascio Committee Chair
Daniel Ashmead Committee Member
James Bodfish Committee Member
Mark Wallace Committee Member
  • stereotypy
  • complexity
  • visual
  • motor
  • electroencephalography
Date of Defense 2019-03-15
Availability unrestricted
Stereotyped behavior is rhythmic, repetitive movement that is invariant in form. It is common in several neurologic and psychiatric disorders, such as autism spectrum disorders (ASD), where it is considered maladaptive. However, it also occurs early in typical development (TD) where it serves an adaptive function in the development of complex, controlled motor behavior. These manifestations of stereotyped behavior have largely been studied independently of one another under the assumption that they originate from separate neurobiological mechanisms. In this body of work, I propose a conceptual model implicating sensorimotor mechanisms in the phenomenology of adaptive and maladaptive stereotypy, and I test this model empirically in two studies. Study 1 tests the model in TD adults. During this study, participants performed a stimulus-tracking task on a computer in the presence and absence of visual feedback while their motor performance (root mean square error), motor complexity (sample entropy) and sensorimotor neural complexity (multiscale sample entropy of the electroencephalography signal) were measured. Study 2 tests the model in adults with ASD. Adults with ASD and TD performed the stimulus-tracking task. Groups were compared on motor performance, motor complexity, and neural complexity in the presence and absence of visual feedback. Additionally, correlations were run to relate these experimental measures to rates of stereotyped behavior in ASD. Consistent with previous literature, Study 1 indicated that visual feedback improves motor performance and increases motor complexity in TD, Additionally, Study 1 revealed that neural complexity, specifically relating to sensorimotor signals, increases with visual feedback. In Study 2 the ASD group demonstrated greater neural complexity and greater differences between visual feedback conditions than TD individuals, specifically in signals relevant to sensorimotor processing. Motor performance, motor complexity and neural complexity correlated with stereotyped behavior in the ASD group. These findings support the role of sensorimotor integration in the complexity and adaptability of motor behavior in healthy populations and in ASD. Additionally, this work helps to establish a method for deriving both kinematic and electrophysiological “signatures” that provide objective markers of individual differences in sensorimotor function among persons with ASD.
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