Cortical traveling wave analysis reveals weaker resting forward theta waves and greater task-related modulation in obsessive compulsive disorder

Obsessive-compulsive disorder (OCD) is associated with abnormalities in large-scale brain network dynamics. Conventional electroencephalography (EEG) captures local oscillatory activity but does not characterize spatiotemporal propagation patterns. This study investigates cortical traveling waves, which index directional information flow across the cortex, to determine whether they provide novel insights into altered neural communication in OCD.

Resting-state (eyes-closed) and task-based (Go/NoGo, Flanker) EEG were recorded from 25 individuals with OCD and 27 healthy controls (HCs). Traveling waves were quantified along midline electrodes using two-dimensional Fast Fourier Transforms to extract forward (posterior-to-anterior) and backward (anterior-to-posterior) propagation in theta (4-8Hz) and alpha (8-13Hz) bands. Group differences were assessed using Bayesian and frequentist linear mixed-effects models controlling for age and sex.

At rest, a significant group-by-direction interaction was observed in the theta band (P = 0.0006), driven by weaker forward traveling wave strength in OCD relative to HC. No group differences were observed for backward waves or in the alpha band. During the Flanker task, the OCD group showed a significantly greater increase in forward theta wave strength from rest than HC (P = 0.022). No associations were found between traveling wave measures and symptom severity.

OCD is characterized by altered theta-band traveling wave dynamics, specifically reduced forward (bottom-up) signaling at rest, and increased task-related modulation during the Flanker task. These findings suggest disrupted hierarchical cortical communication and inefficient engagement of sensory-driven processes. The absence of symptom correlations suggests a potential trait-like neurophysiological marker or endophenotype of OCD.