Title: How I learned to Stop Worrying and Love the Null Result: Similarities in Sensory Responses in People with Autism and Neurotypicals
Speaker: Dr John S. Butler, Technological University Dublin
The talks will be held virtually this semester via Microsoft Teams. Link to join the meeting is given below. All are welcome.
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ABSTRACT:
I will discuss the application of statistical and analysis methods to investigate an on-going debate whether children with Autism spectrum disorder (ASD) have unreliable sensory processing. 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. If this is correct a number of straightforward predictions can be made about the evoked brain signals; 1) the averaged evoked response should be broader and have a delayed peak for all components; 2) people with ASD should have a greater variability of phase dispersion across single trials.
Here, we examined this thesis in a matched cohort of typically developing children and children with ASD, using high-density EEG recordings of visual and somatosensory evoked responses. We first used classical statistical methods and Bayes Factors to investigate differences or similarities of the groups’ evoked responses [1]. We then processed the single trials to look at amplitude or phase differences at different frequencies.
Finally, 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 and data 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 allowed us to embrace the null and argue against a straightforward unreliability hypothesis and instead favors an argument taking into account subtleties and specializations that are present in a complex disorder such as autism.
If there is time, I will talk about my more recent work in embracing the null [2] and some of my ongoing work simulating neuronal responses [3].
References
[1] John S. Butler, Sophie Molholm, Gizely N. Andrade, John J. Foxe, An Examination of the Neural Unreliability Thesis of Autism, Cerebral Cortex, Volume 27, Issue 1, January 2017, Pages 185–200, https://doi.org/10.1093/cercor/bhw375
[2] Fearon, C., Butler, J.S., Waechter, S.M. et al. Neurophysiological correlates of dual tasking in people with Parkinson’s disease and freezing of gait. Exp Brain Res 239, 175–187 (2021). https://doi.org/10.1007/s00221-020-05968-8
[3] Website: https://johnsbutler.netlify.app
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