The neural dynamics of sequence-specific behavior in obsessive-compulsive disorder

Poster Session A - Saturday, April 13, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Hannah Doyle¹ (hannah_doyle1@brown.edu), Sarah Garnaat², Nicole McLaughlin¹, Theresa M. Desrochers¹; ¹Brown University, Providence, RI, ²Dartmouth-Hitchcock Medical Center, Lebanon, NH

Humans naturally organize tasks into sequences, where a rule dictates the sequential structure rather than individual task identity (e.g., in the sequence of making a cup of coffee, beans could be swapped for grounds). Differences in such abstract sequence processing could in part underlie behavior in obsessive-compulsive disorder (OCD), such as repeating tasks and sequential rituals, and lead to delays in completing everyday tasks. We tested the hypothesis that OCD symptoms result from differential abstract sequence representation. Previously, we established that increasing activation (‘ramping’) in the rostrolateral (RLPFC), but not rostromedial, prefrontal cortex was necessary for abstract sequence performance in healthy controls (HCs) (Desrochers et al., 2015; 2019). Using the same abstract sequence task during fMRI in patients with OCD, we observed unique ramping activity in medial PFC that did not occur in HCs. These neural differences were present despite minimal behavioral differences (Doyle et al., 2023). Ramping did not differ between the groups in the RLPFC. However, in the OCD group, RLPFC ramping did correlate positively with obsessive-compulsive severity (r = 0.43, p = 0.037) and medial PFC ramping correlated negatively with feelings of incompleteness (r = -0.42, p = 0.041), suggesting differential roles for these regions in mediating OCD symptomatology. Together, these findings suggest a novel and dynamic involvement of medial PFC and RLPFC in the performance of abstract task sequences in patients with OCD. These could inform potential treatments for OCD in the future to aid disruptions in daily life due to sequencing errors.

Topic Area: EXECUTIVE PROCESSES: Goal maintenance & switching