Seminar 06/11/15: An Examination of the Neural Unreliability Thesis of Autism

An Examination of the Neural Unreliability Thesis of Autism
John Butler
Dublin Institute of Technology
Friday 6 November 2015
1pm, Blue Room, DIT Kevin Street

Abstract:

Reports have recently emerged pointing to the possibility that evoked sensory-neural responses might show greater trial-to-trial variability in individuals on the autism spectrum disorder (ASD). The general notion is that signal averaging procedures typically used in neurophysiological and neuroimaging studies obscure the fact that there are ongoing and presumably relatively dramatic fluctuations in responsiveness to individual events.

Here, we examined this thesis in a matched cohort of typically developing children and children with ASD (N=20), using high-density electrical recordings of visual and somatosensory evoked responses. If the thesis is correct that people with ASD have an unreliable evoked response, a number of straightforward predictions can be made; 1) the averaged evoked response should be broader and have a delayed peak for all components; 2) ASD individuals should have a greater variability of phase dispersion across single trials.

Furthermore, we simulated an unreliable evoked response by introducing temporal and amplitude variability at a single trial level. This simulated data was then compared with the observed TD and ASD data, and illustrated the predictions of the unreliable evoked response and the sensitivity of the measures to small perturbations.

Our data show highly similar reliability in the neural responses to visual and somatosensory stimuli in our matched groups, while the simulated data show differences predicted by the unreliability thesis. These results against a straightforward unreliability hypothesis and instead favours an argument taking into account subtleties and specializations that are present in a complex disorder such as autism.