Resting-State EEG and MEG Correlates of Auditory Hallucinations in Adults With Schizophrenia: A Systematic Review

Abstract

Auditory hallucinations (AH) are reported by 60–75% of people diagnosed with schizophrenia. They have been linked to a range of cortical structural and functional changes. We systematically reviewed electroencephalogram (EEG) and magnetoencephalography (MEG) resting-state studies of adults with schizophrenia experiencing auditory hallucinations (verbal and/or nonverbal). After searching for relevant studies using the PubMed and Web of Science databases, we applied the PRISMA method to exclude duplicates and studies not matching our inclusion criteria. The selection process yielded 16 studies (8 EEG, 5 MEG, 2 qEEG-LORETA, and 1 EEG-fMRI). Results suggest that both EEG frequency changes and altered intra- and interhemispheric coherence play a role in the generation or perception of AH. Also, while overactivity of the auditory cortex and disruption of normal activity in speech-related areas have been proposed, MEG research suggests that distinct symptoms in schizophrenia may be related to different types of brain alterations and also that different cortical regions may be involved in different types of AH. More research in younger populations is needed and follow up studies should evaluate the effects of targeted interventions during the occurrence of hallucinatory episodes.