Electrophysiological Neuroimaging using sLORETA Comparing 22 Age Matched Male and Female Schizophrenia Patients

Abstract

BACKGROUND: Standardized low resolution brain electric tomography (sLORETA) is a validated neuroimaging method for localizing the electric activity in the brain based on multichannel surface electroencephalogram (EEG) recordings, having the benefit of improved time resolution of EEG measurements, better than that of functional magnetic resonance imaging (fMRI), and with a spatial resolution similar to that of fMRI.

OBJECTIVE: The purpose of this electrophysiological neuroimaging study was to provide a deeper mechanistic understanding of both olanzapine and risperidone pharmacodynamics relative to gender. In doing so, we age-matched 22 men and women and initially evaluated their resting-state EEG recordings and later used sLORETA to visualize the differences in brain activity amongst the two patient groups.

METHODS: In this investigation, EEG data were analyzed from male and female schizophrenia patients treated with either olanzapine or risperidone, both atypical antipsychotics, during their in-patient stay at the Department of Psychiatry. Twenty two males and females were age-matched and EEG recordings were analyzed from 19 silver/silver chloride electrodes. Thirty-seconds of resting EEG were spectrally transformed into sLORETA. Three-dimensional statistical non-paramentric maps for the sLORETA global field power within each band were finally computed.

RESULTS: The results indicated that, relative to males patients, females schizophrenia patients had increased neuronal synchronization in delta frequency, slow-wave, EEG band located in the dorsolateral prefrontal cortex, within the middle frontal gyrus (t= -2.881, p <0.03580). These findings suggest that females experience greater dopamine receptor and serotonin receptor neuronal blockade relative to age-matched males. Further, our findings provided insight to the pharmacodynamics of secondgeneration antipsychotics olanzapine and risperidone.

CONCLUSION: When compared to male patients, female patients suffering from schizophrenia have dopamine and serotonin receptors that are blocked more readily than age-matched male schizophrenia patients. Clinically, this may translate into a quicker time to treatment-response in females as compared to male patients.