This pilot investigation explored the utility of combining physiologic and behavioral measures of sensory responsivity to identify the over-responsive subtype of Sensory Modulation Dysfunction (SMD). Electrodermal activity (EDA) was assessed in several children (n = 4; F = 1; M = 3; ages = 4-7) referred based on a parent perception of Sensory Over-Responsivity to our laboratory for the development of the Sensory Over-Responsivity scale (SOR; Miller and Schoen, in preparation). EDA was recorded at rest and during stimulation in several different sensory modalities to evaluate both arousal and sensory orienting. For two cases, physiologic data were compared to behavioral data from the SOR assessment and the Short Sensory Profile (SSP; Macintosh, Miller, et al., 1999a).
These select cases exhibited different electrodermal arousal and orienting patterns. Case one exhibited relatively lower tonic arousal, as measured by skin conductance level (avg. baseline SCL = 4.2 µS) and nonspecific skin conductance responses (NSR) (baseline nonspecific rate = 1.6 NSR/min), compared to case 2 (avg. baseline SCL = 9.2 µS; nonspecific rate = 11.6 NSR/min). In terms of phasic orienting, the patterns for the two cases reversed, such that orienting amplitudes were higher overall across all sensory modalities for case one compared to case two. Both cases also exhibited atypical behavioral responses to direct sensory stimulation on the SOR assessment. Case one was most sensitive to auditory stimulation (z-scores = -3.05). For case two, sensitivity was mainly indicated in the olfactory (z-score = -2.43) and gustatory (z-score = -2.32) domains. These findings were consistent with finding atypical sensory responses on the SSP, where the total SSP z-score was -3.92 for case one and -2.23 for case 2. Comparison of the physiology and behavior for these two cases indicates that EDA is relatively consistent with the SOR assessment for case one in terms of identifying sensitivity to auditory stimulation, but is less consistent for case two.
This work extends the results of previous studies finding atypical sensory orienting in children with SMD associated with atypical behavioral responses to sensory stimulation. Furthermore, this data is consistent with previous results suggesting that high amplitude orienting is associated with poorer performance on the SSP (Macintosh, Miller, et al., 1999b). These results suggest that combined psychophysiologic and behavioral assessment of both arousal and sensory responsivity may facilitate the discrimination of some heterogeneity in SMD. For example, the pattern of low arousal combined with high amplitude orienting seen for case one may be indicative of the over-responsive subtype of SMD, while the pattern of high arousal paired with low amplitude orienting seen for case two may be indicative of a different subtype of SMD
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