Validating Sensory Processing Disorders through Concomitant Neurophysiological Neuropsychological, Psychophysiological, and Neurobiological Measures

Summary Statement: Investigates the relationship of stress (cortisol levels) and genetic markers for alpha-7 receptors sites in EEG/ERP measures to sensory gating measures in children with and without sensory processing disorders.

Full Abstract: Sensory gating, the brain's ability to suppress repeated, irrelevant sensory input and to selectively regulate the sensitivity to sensory stimuli, is an essential brain mechanism and protective function of the central nervous system. Previous electrophysiological studies on sensory gating by us and others have shown that most adults and children without disabilities display sensory gating to repetitive auditory stimulation. However our recent research shows that, as a group, children with sensory processing disorders (SPD) demonstrate significantly less auditory sensory gating than an age-matched peer group of children without disorders. In addition children with SPD did not show a relationship between sensory gating and age that was observed in their matched peer group. Our recent electrophysiological data further illustrates that children with sensory processing disorders separate into two subtypes, one that is hypersensitive and one that is hyposensitive to auditory stimuli.

The proposed project focuses on the task of validating the diagnosis of sensory processing disorders through a series of inter-related data gathering activities on each child in either of two groups, children with SPD and children without disorders. First, we propose to further refine our present ERP techniques to produce even more reliable electrophysiological measures of brain processing of auditory stimuli in both the sensory gating and the sensory registration paradigm. Further work with these paradigms will allow us to refine our classification procedures that are suggestive of the presumed subtypes of hypersensitivity and hyposensitivity and at the same time, validate, through replication, our previous findings. Second, we will obtain behavioral measures to provide indices of sensory function in everyday activities using the Sensory Profile (Dunn, 1999) and the Sensory Responsivity Scale (SENSor) assessment and inventory (Miller, in preparation). To these measures, we will add several neuropsychological measures of cognitive and executive functioning such as IQ, maze solving, perceptual motor speed and digit span recall. The addition of these cognitive and executive functioning measures may provide a demonstration of the dissociation between the two groups where they match on cognitive measures but differ on sensory measures. Furthermore, the inter-relationship of these behavioral measures and their relationship to the sensory gating and sensory registration neurophysiological measures will also be explored. Third, the project will begin to explore how domains other than neurophysiology (i.e., ERP measures) and neuropsychological (i.e., the behavioral measures of sensory and cognitive abilities) might contribute to the understanding and defining of sensory processing disorders. For each child, we propose to collect measures from the psychophysiology domain (i.e., cortisol levels as an indicator of anxiety or stress) and neurobiological domains (i.e., DNA sampling for the nicotinic alpha 7 receptors as an indicator of genetic predisposition).

By examining the inter-relationship of measures from the domains of neurophysiology, neuropsychological, psychophysiology, and neurobiological obtained within a single study of both children with and without sensory processing disorders, we will have a better understanding of: (1) the underlying brain mechanisms of sensory processing disorders; (2) how to reliably diagnose sensory processing disorders, and (3) how to better develop potential strategies for treatment and accessing their effects through well designed treatment efficacy studies.

Funded by: Wallace Research Foundation for the period of 1/1/06 to 12/31/06.

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