Neural evidence for the influence of cognitive control by facial emotion under varying task difficulty in individuals with borderline personality disorder traits.

Borderline personality disorder traits (BPD traits) represent subclinical characteristics associated with borderline personality disorder (BPD), which are marked by impaired cognitive control of emotion processing. Although the cognitive control deficit of negative emotions is a core feature of BPD, the characteristics and neural basis of this deficit in non-clinical BPD traits individuals remain unclear. The present study employed a novel facial majority function task (fMFT) combined with event-related potential (ERP) recording to explore the cognitive control of negative facial emotion under varying task difficulty in individuals with high BPD traits. We recruited 50 high BPD traits participants and 50 low BPD traits participants for the fMFT. The behavioral results showed that under low and medium task difficulty conditions, there were no significant differences in reaction time and accuracy between the two groups. However, under negative emotion-high task difficulty conditions, the reaction time of the high BPD traits group was significantly longer than that of the low BPD traits group, and the accuracy was significantly lower than that of the low BPD traits group. The ERP results showed that high BPD traits group exhibited reduced frontal N200 amplitudes and increased parietal P300 amplitudes compared to the low BPD traits group. Furthermore, both groups exhibited decreased LPP amplitudes with increasing task difficulty in positive emotion conditions, but this task difficulty effect was not significant in negative emotion conditions in the high BPD traits group. These findings demonstrate that BPD traits leads to selective deficits in cognitive control of emotion processing, and negative emotion leads to their impairment in the processing of conflict monitoring and inhibition with task difficulty increasing.