Specific and unspecific auditory hallucinations in patients with schizophrenia - A magnetoencephalographic study

Background/Aims: Different neuroimaging techniques have indicated that auditory association and language cortices are active in patients with schizophrenia and auditory hallucinations. Auditory verbal hallucinations are thought to arise from a disorder of inner speech, but little is known about their origin. Methods: Spontaneous magnetoencephalographic (MEG) measurements were recorded with a 74-channel two-sensor system (BIOMAGNES II) in 16 patients with schizophrenia and 8 healthy subjects in frequency ranges from 2 to 6 and 12.5 to 30 Hz. Eight patients had auditory hallucinations during the MEG recordings. Results: The total group of patients with schizophrenia showed a statistically significant elevation of the number of dipoles and dipole density maxima in slow frequency ranges compared to healthy subjects (p < 0.001). Significant dipole activities in the fast frequency range were only found during auditory hallucinations (p < 0.001). Dipole localization was concentrated in frontal and temporal regions depending on different qualities of hallucinations. In patients with external imperative voices we found a parallel activation of the dorsolateral frontal and temporal cortex. Conclusion: We conclude that various auditory hallucinations in schizophrenia are induced by different neuronal activities and may be represented by different cortical regions. Copyright (c) 2007 S. Karger AG, Basel.