The relationships between subclinical OCD symptoms, beta/gamma-band power, and the rate of evidence integration during perceptual decision making

Previous studies have demonstrated that the rate of evidence integration during perceptual decision making, a specific computationally defined parameter, is negatively correlated with both subclinical symptoms of OCD measured on a continuum and categorically diagnosed patient status. However, the neural mechanisms underlying this deficit are unknown. Separate work has shown that both gamma and beta-band power are related to evidence integration, and differences in beta-band power in particular have been hypothesized to hinder flexible behavioral control. We sought to unify these two disparate literatures, one on OCD-related information processing differences constrained by behavioral data alone, and the other on the neural correlates of evidence integration. Using computational modeling and scalp EEG, we tested (N = 67) the relationships between subclinical symptom scores, drift rate, and gamma/beta-band activity during perceptual decision making. We replicated both prior work showing deficits in evidence integration as a function of OCD symptoms, and work showing a relationship between evidence integration and gamma and beta-band power. As predicted, the slope of beta-band power was correlated with OCD symptoms. However, the relationships between OCD symptoms and drift rate and the slopes of gamma and beta-band power and drift rate remained unchanged when simultaneously accounting for all variables, speaking against the hypothesis that differences in band-band power explain drift rate deficits.