1 - (SYM 3) Vibration Moderates Neural and Subjective Sensitivity to Overwhelming Visual Information in Autistic Adults

  

Background: Sensory sensitivity is typically considered to involve allocation of more resources to sensory processing than are available, yielding feelings of overwhelmedness, inability to handle incoming information, conflict, and failure. In other domains, allocation of resources beyond capacity yield deallocation of neural resources, akin to “giving up.” If this formulation holds, then multimodal stimulation should cause increased distress, and potentiated decreased resource allocation.

  

Methods: 28 autistic individuals, selected to vary in gender and ethnicity, were compared to a cohort of non-autistic controls on neural and subjective reactions to a flashing checkerboard task with and without periodic changing vibration on their chest in a 2 (checkerboards/no-checkerboard) x 2 (vibration/no-vibration) design using functional magnetic resonance imaging (fMRI). Reactivity was examined in 14 networks that have been identified as of interest in cognitive and emotional information processing in autism.

  

Results: For many autistic individuals, visual  overstimulation (flashing checkerboards) yielded blunted neural reactivity and was perceived as aversive. Adding vibration for these individuals tended to yield increased reactivity and was perceived as less overstimulating; many people described vibration as akin to being able to self-stimulate. These neural and narrative pictures did not emerge for non-autistic individuals (for autistic v. control participants with flashing checkerboards alone autistic v control Cohen’s d< -.3 for 8/14 networks; on vibration + checkerboards, Cohen’s d >.3 for 12/14 networks). 
  

Conclusions: Initial data suggest that overstimulation is not a uniform cross-modal phenomenon for autism, and that some kinds of stimulation may compete with others, leading to potential future directions for intervention.