Altered pre-supplementary motor area recruitment during semantic inhibition in individuals with elevated obsessive–compulsive traits

Background: Inhibitory control dysfunction has been implicated in obsessive–compulsive disorder (OCD), but neuroimaging research has focused predominantly on motor response inhibition. Whether obsessive–compulsive traits are associated with altered neural recruitment during semantic inhibition remains unclear.Methods: Forty right-handed participants with lower or elevated obsessive–compulsive traits performed an fMRI adaptation of the Hayling Sentence Completion Task. Participants either selected an expected sentence completion (initiation) or suppressed this strongly prepotent response to select an unrelated word (inhibition). Whole-brain and anatomically defined region-of-interest (ROI) analyses examined task-related activation and Group × Condition interactions, with particular interest in the pre-supplementary motor area (preSMA) and SMA proper.Results: Semantic inhibition produced a robust behavioural cost in reaction times and error rates, with no significant differences between groups. Whole-brain analysis identified the strongest inhibition-related activation in the left preSMA. The exploratory Group × Condition analysis also yielded its peak interaction in this region. Anatomically defined ROI analysis showed a significant Group × Condition interaction in the preSMA after family-wise error correction (t = 2.56, pFWE = .012), reflecting a larger inhibition-related increase in controls compared to individuals with elevated obsessive–compulsive traits. The corresponding interaction in SMA proper did not reach statistical significance (t = 1.74, pFWE = .084).Conclusions: Elevated obsessive–compulsive traits were associated with altered preSMA recruitment during semantic inhibition in absence of behavioural impairment. This extends neural markers of obsessive–compulsive alterations from the domain of motor inhibition to that of semantic inhibition.