Neural representations of emotional response inhibition reveal trait and state biomarkers in pediatric bipolar disorder.

Pediatric bipolar disorder (PBD) is characterized by disrupted cognitive control, particularly in response inhibition under emotional interference. However, the neural underpinnings of these deficits, particularly how these impairments vary across emotional valence and whether they reflect trait markers or state alterations, remain unclear. While traditional univariate fMRI analyses reveal broad activation differences, they lack sensitivity to fine-grained neural patterns. This study aims to examine the neural representations of emotional response inhibition in PBD under valence-dependent interference using representational similarity analysis(RSA). We included manic (n = 15) and euthymic (n = 18) PBD patients, along with matched healthy controls (n = 17). Participants completed an emotional Go/NoGo task with happy, sad, and neutral faces during fMRI. Six contrast conditions were modeled to assess trait- and state-related effects. Whole-brain searchlight RSA (8 mm radius) was used to identify regions showing group differences in neural representational patterns. Results showed that emotional response inhibition engaged distributed neural systems, with distinct patterns across valence conditions. Compared to controls, PBD patients exhibited trait-related representational differences during happy inhibition, sad inhibition, and sad-specific inhibition, involving regions such as the precentral gyrus, middle frontal gyrus, and inferior parietal lobule. Manic patients showed state-related reductions in neural representations during sad-specific inhibition within frontal areas compared to euthymic patients. These findings indicate that emotional response inhibition deficits in PBD arise from both trait- and state-dependent abnormalities in neural representations. The study highlights the value of multivariate fMRI in uncovering clinically relevant biomarkers and provides a novel framework for developing phase-specific interventions.