Somatosensory Event-Related Potentials and Association with Tactile Behavioral Responsiveness Patterns in Children with ASD

Abstract

The goal of this study was to explore neural response to touch in children with and without autism spectrum disorder (ASD). Patterns of reduced (hypo-responsiveness) and enhanced (hyper-responsiveness) behavioral reaction to sensory input are prevalent in ASD, but their neural mechanisms are poorly understood. We measured event-related potentials (ERP) to a puff of air on the fingertip and collected parent report of tactile hypo- and hyper-responsiveness in children with ASD (n = 21, mean (SD) age 11.25 (3.09), 2 female), and an age-matched typically developing comparison group (n = 28, mean (SD) age 10.1 (3.08, 2 female). A global measure of ERP response strength approximately 220-270 ms post-stimulus was associated with tactile hypo-responsiveness in ASD, while tactile hyper-responsiveness was associated with earlier neural response (approximately 120-220 ms post-stimulus) in both groups. These neural responses also related to autism severity. These results suggest that, in ASD, tactile hypo- and hyper-responsiveness may reflect different waypoints in the neural processing stream of sensory input. The timing of the relationship for hyper-responsiveness is consistent with somatosensory association cortical response, while that for hypo-responsiveness is more consistent with later processes that may involve allocation of attention or emotional valence to the stimulus.

Figure 1

Normalized GFP different between puff and sham conditions in the TD (A) and ASD (B) groups. Vertical lines indicates onset of stimulus. Orange bars illustrate periods of significant GFP difference between puff and sham as measured by paired t tests within each group. (C): Five microstates in the TD (reference) group, defined as periods of stable topography to the puff stimulus, measured with Cartool’s cluster-based segmentation. Of these five, microstates 2 (121–218 msec post-stimulus) and 3 (219–268 msec post-stimulus) were wholly contained within the window of significant difference common to both ASD and TD (dark orange bar), and thus were the foci of subsequent analyses. (D): Topographic maps in the TD (reference) group, depicting GFP for the two microstates of interest.

Figure 2

Raw ERP data (uV) for a representative central electrode contralateral to stimulation site (C3/C4) for (top) TD and (bottom) ASD groups.

Figure 3

Relations between global field power (GFP) and tactile responsiveness. A: Hypo-responsiveness (measured by the SEQ) and its relation to GFP in microstate 2 (121–218 ms post-stimulus); B: Hyper-responsiveness (measured by the SP) and its relation to GFP in microstate 3 (219–268 ms post-stimulus).