Self-disorders in schizophrenia - and ERP study of pre-reflective and reflective self-experience

Background & hypothesis: Self-disorders (SDs) reflect abnormalities in the basic, or pre-reflective, self and are frequently present in schizophrenia spectrum disorders (SSDs). Despite their significance, the neural correlates of these abnormalities remain underexplored. This study investigates event-related potential (ERP) correlates of SDs using a cognitive task, hypothesizing that patients with SDs would show alterations in pre-reflective and reflective self-processing. We also hypothesized that the severity of SDs, measured by the Examination of Anomalous Self Experience (EASE), would correlate with ERP changes related to the pre-reflective self and that these alterations would involve cortical midline structures (CMS). Study design: Thirty-five individuals with SSDs and sixty-two healthy controls completed a verbal trait-judgment task during EEG recording that required pre-reflective and reflective self-referencing. We compared ERP responses between groups and conditions and examined correlations between EASE scores and EEG maps. Post-hoc source localization identified brain regions corresponding to pre-reflective self-processing. Study results: Results revealed significant ERP differences for the pre-reflective self at 300 ms post-stimulus, while reflective self differences occurred earlier. EASE scores correlated with EEG maps associated with pre-reflective self-processing. Source estimation indicated increased activation in the dorsomedial prefrontal cortex (dmPFC), Broca's area, sensorimotor cortex, and temporal regions in patients with SSDs during pre-reflective self-processing. Conclusions: These findings provide neuroimaging evidence of alterations in both pre-reflective and reflective self-experience in individuals with SDs. The correlates of pre-reflective self-experience were linked to the severity of SDs and involved brain regions overlapping with cortical midline structures, particularly the medial prefrontal cortex (mPFC).