The Possible Role of Insula and Default Mode Network in Schizophrenia During an Auditory Task: A Pilot EEG-fMRI Analysis

The impairment of auditory perception in schizophrenic patients (SCZ), compared to healthy controls (HC), has been largely studied, identifying the N100 event-related potential as a possible biomarker for the discrimination between these two groups. However, the hemodynamic activity underlying this differential process is still not clear. In this context, the simultaneous combination of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) could unveil the hemodynamic correlates of neuronal events of interest, such as the N100, and inform on brain auditory processing with a higher spatial and temporal resolution than the single techniques. In this pilot work, we used EEG-driven fMRI and fMRI task-based connectivity analyses to investigate the neurovascular differences between two HCs and one SCZ during a three-tones auditory task. Although no differences were reported in terms of N100 amplitude, the EEG-driven fMRI analysis showed different N100 correlates between the two groups in the left insula, right prefrontal cortex, and precuneus. The different connectivity between participants and task conditions has been assessed using the left insula as seed for the generalized Psychophysiological Interactions (gPPI) model. The analysis showed generally lower connectivity for SCZ and alterations in regions included in the default mode and salience networks.