Date of Award

2011

Degree Type

Dissertation

Degree Name

PhD Health Sciences

Department

Health and Medical Sciences

Advisor

Susan Simpkins

Committee Member

Valerie Olson

Keywords

Autistic children, Parasympathetic nervous system, Autistic Disorder, Case studies

Abstract

This study was a preliminary investigation into the reliability of cardiac vagal tone (CVT) as a measure of regulatory sensory processing in typically developing children and children with autistic spectrum disorders (ASD). We also examined group differences in CVT at rest and in response to sensation and the relationship of CVT to behavioral measures of sensory processing. The goals of this study were to answer three related research questions: 1. Is CVT a reliable measure of regulatory sensory processing? 2. Do children with ASD respond to sensory information differently than typically developing children? 3. Is there a relationship between physiologic and behavioral measures of regulatory sensory processing? The participants were 15 typically developing boys and 11 boys with ASD. We measured CVT two times, within 4 weeks, during the Sensory Challenge Protocol (Miller, 1999). Behavioral responsivity to sensation was measured using the Short Sensory Profile (SSP) (Dunn, 1997). Reliability was assessed using intraclass correlation coefficients, vagal response patterns were assessed using repeated measures analysis of variance and t-tests and multivariate analysis of variance were used to look at between group differences in vagal measures and SSP scores. Pearson Correlation coefficients were used to examine relationships between CVT and SSP scores. Results of this study indicate that CVT is a reliable measure of regulatory sensory processing. Highlighting the fact that the children with ASD demonstrate greater statistical reliability than the typically developing children. We also found that the children with ASD demonstrate significantly lower baseline vagal tone. Further, we found the two groups responded differently to sensation. Post hoc tests revealed a significant difference between the groups on vagal responsivity to vestibular stimulation, with the group of children with ASD demonstrating less reactivity. Additionally, the ASD group demonstrated significantly lower scores on all sections of the SSP except movement sensitivity. Lastly, several correlations between vagal responses during the SCP and SSP sections were noted. The results of this study point to a relationship between physiology and behavior, suggesting that children with ASD demonstrate less physiologic flexibility which may play a role in the decreased behavioral flexibility seen in this population.

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