Feasibility of Using Functional Near-Infrared Spectroscopy for Characterizing Misophonia-Related Brain Activity

Significance: Misophonia is characterized by decreased tolerance to specific sounds ("triggers") that evoke negative emotional, physiological, and behavioral responses. To understand the neural mechanisms underlying misophonia, functional neuroimaging has been proposed such as functional magnetic resonance imaging (fMRI). However, the fMRI environment introduces substantial noise that increases anxiety, which is one of the comorbidities of misophonia, confounds auditory stimuli, and is costly. We therefore propose an alternative, functional near-infrared spectroscopy (fNIRS) to detect misophonia-related responses. Aim: We evaluated the feasibility of fNIRS to detect misophonia-related sound-evoked responses. Approach: We measured fNIRS, electrodermal activity (EDA), and photoplethysmography (PPG) data from ten adults with minimal to mild misophonia symptoms while they listened to trigger, unpleasant, and neutral sounds. Participants rated their annoyance and antisociality after each sound. Results: Compared with neutral sounds, trigger and unpleasant sounds received higher subjective ratings and evoked greater neural response in the orofacial area. Neural responses tended to increase with annoyance ratings. Significantly lower heart rate (HR) was observed during unpleasant sounds than during neutral and trigger sounds, with no significant difference in EDA features. Conclusions: fNIRS can measure misophonia responses in a quiet setting. Both brain and physiological responses have the same trend observed in prior fMRI studies, verifying its feasibility.