Schedule of Events | Symposia

Neurochemical and functional circuitry alterations underlying goal-directed and habitual behaviour in obsessive-compulsive disorder

Poster Session A - Saturday, March 29, 2025, 3:00 – 5:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Máiréad Healy¹ (mph58@cam.ac.uk), Yuanxi Li¹, Marjan Biria², Maité Crespo-García¹, Zoe Kourtzi¹, Trevor Robbins¹; ¹University of Cambridge, ²University College London

Introduction: Obsessive-compulsive disorder (OCD) involves an imbalance in frontal-striatal circuitry, favouring habitual behaviours over goal-directed actions. This imbalance may result from altered neurochemical regulation of excitatory and inhibitory processes in these systems. However, the interplay between neurochemical and functional brain mechanisms influencing compulsivity remains poorly understood. Methods: We conducted a multimodal imaging study with 20 OCD participants and 20 matched controls to explore structural-functional mechanisms underlying compulsive behaviour. Using 7-Tesla 1H-MRS and an optimised MRS sequence (semi-LASER), we quantified Glu, Gln, and GABA in the anterior cingulate cortex (ACC) and supplementary motor area (SMA) — regions strongly linked to OCD. Participants also completed an fMRI contingency degradation task to assess their habitual (stimulus-response) versus goal-directed (action-outcome) tendencies. Results: Preliminary findings suggest that compulsive behaviours correlate with neurochemical markers in the ACC and SMA, indicating a potential alteration in the excitatory/inhibitory (E/I) balance of neurometabolites such as Glu and GABA. Neurochemical imbalance was linked to increased habitual responding in the SMA across the entire sample (Pearson's r = 0.26, p = 0.02, p-FDR = 0.06). Participants with OCD showed a similar relationship within the ACC (Pearson's r = 0.38, p = 0.02, p-FDR = 0.04). Future analyses will examine how functional activation corresponds to neurochemical shifts to explain the imbalance between goal-directed and habitual behaviours. Conclusion: We hypothesize that E/I balance and functional activity interactions predict habitual versus goal-directed behaviour, offering insights into the mechanisms of behavioural flexibility.

Topic Area: EXECUTIVE PROCESSES: Goal maintenance & switching