Analyzing brain connections in sound tolerance disorders using fMRI and machine learning

Authors: Shagun Ajmera *1; Arit Banerjee 1; Rafay Khan 1; Fatima Husain 1

1 University of Illinois Urbana Champaign

Sound tolerance disorders are marked by an aversion to everyday sounds. Adults with ‘loudness hyperacusis’ find ordinary noises too loud and discomforting. Recent work has identified ‘misophonia’ as a disorder where unpleasant emotions are evoked towards sounds produced by others (e.g chewing, sniffling). We study the underlying spontaneous brain interactions (functional connectivity; FC) involved in these conditions, and hypothesize that altered brain connectivity characterizes sound intolerance.

Resting state functional MRI data was acquired on participants with misophonia (n=23), hyperacusis (n=13) and controls (n=24) and parcellated into functional regions (ROIs). FC was measured between fMRI activity of ROIs using Pearson’s correlation coefficient. Logistic regression models were trained on the battery of connectivity values for the two classification problems – (1) misophonia vs.control, (2) hyperacusis vs. control. The connection weights learnt across several model iterations were averaged, thresholded, and visualized on brain maps (see figure).

The overall accuracy of the classification models for both misophonia and hyperacusis was >60%. Using bootstrapping and regularization, specific connections out of several thousands were extracted, which distinguished the other two groups from controls. Unlike controls, the hyperacusis group showed decreased FC between somatosensory and somatomotor regions, and in parts of default mode network. In misophonia, FC of right premotor cortex was higher with inferior parietal lobule and lower with superior parietal lobule relative to controls. The FC between inferior temporal gyrus and Broca’s area were weaker in misophonia than in controls.

In this ongoing study, preliminary analyses show more extensive FC differences in misophonia than in hyperacusis. Altered FC of motor areas is common to both, but higher connectivity of the attention network is specific to misophonia, suggesting delineation of the two disorders.