Time-Resolved EEG Decoding of Semantic Processing Reveals Altered Neural Dynamics in Depression and Suicidality

TL;DR

This study used time-resolved EEG decoding during a sentence evaluation task to reveal altered neural dynamics in semantic processing among individuals with depression and suicidality, providing potential neurocognitive biomarkers.

Contribution

It introduces a novel EEG decoding approach to characterize semantic processing differences in depression and suicidality, highlighting altered neural timing and engagement.

Findings

Altered timing and amplitude of semantic decoding in clinical groups

Broader cross-temporal generalization in depression and suicidality

Enhanced frontocentral and parietotemporal contributions in affected individuals

Abstract

Depression and suicidality affect cognitive and emotional processes, yet objective, task-evoked neural readouts of mental health remain limited. We investigated the spatiotemporal dynamics of affective semantic processing using multivariate decoding of time-resolved, 64-channel electroencephalography (EEG). Participants (N=137) performed a sentence-evaluation task with emotionally salient, self-referential statements. We identified robust neural signatures of semantic processing, with peak decoding accuracy between 300-600 ms -- a window associated with rapid, stimulus-driven semantic evaluation and conflict monitoring. Relative to healthy controls, individuals with depression and suicidal ideation showed earlier onset, longer duration, and greater amplitude decoding responses, along with broader cross-temporal generalization and enhanced contributions from frontocentral and parietotemporal components. These findings suggest altered sensitivity and impaired disengagement from emotionally salient content in the clinical groups, advancing our understanding of the neurocognitive basis of mental health and establishing a compact and interpretable EEG-based index of semantic-evaluation dynamics with potential diagnostic relevance.