Cathodal tDCS over right orbitofrontal cortex enhances the ability in subclinical obsessive-compulsive disorder to
Zhongqiang Ruan1, Ziyan Li1, Xiaoshu Luo1
1Center for the Study of Applied Psychology, Guangdong Key Laboratory of Mental Health and Cognitive Science and School of Psychology, South China Normal University, Guangzhou, China; Key Laboratory of Brain, Cognition and Education Sciences, Philosophy and Social Science Laboratory of Reading and Development in Children and Adolescents (South China Normal University), Ministry of Education, China.
Abstract:
While transcranial direct current stimulation (tDCS) targeting the orbitofrontal cortex (OFC) demonstrates therapeutic potential for obsessive-compulsive disorder (OCD), its neurocognitive mechanisms leading to reduced compulsive behaviors remain poorly understood. This study investigates the effects of stimulating the OFC on impaired arbitration between model-based (MB) and model-free (MF) reinforcement learning systems in subclinical OCD. In a randomized, sham-controlled trial, participants with elevated Obsessive-Compulsive Inventory-Revised (OCI-R) scores received six sessions of anodal (excitatory; n = 30), cathodal (inhibitory; n = 31), and sham (n = 32) tDCS over the right OFC, respectively. Arbitration control was quantified pre-/post-stimulation using a two-step decision-making task with computational modeling of MB-MF dynamics. Cathodal tDCS significantly enhanced inhibition of MB-to-MF transitions during MB-optimal complex task condition, promoting stable MB control (p < 0.001). Anodal stimulation showed no significant effects relative to sham. Right OFC cathodal tDCS improves arbitration control in subclinical OCD by facilitating context-appropriate MB strategy implementation, revealing a novel therapeutic mechanism for compulsivity remediation.
