Aberrant evoked and resting state EEG in schizophrenia

Aberrant evoked and resting state EEG in schizophrenia M Roinishvili¹, E Chkonia², M Tomescu³, A Brand⁴, C Michel³, M Herzog⁵, C Cappe⁶
¹Vision Research Laboratory, I. Beritashvili Center of Experimental Biomedicine, Georgia ²Department of Psychiatry, Tbilisi State Medical University, Georgia ³Functional Brain Mapping Lab, University of Geneva, Switzerland ⁴Institute of Psychology and Cognition Research, University of Bremen, Germany ⁵Laboratory of Psychophysics, École Polytechnique Fédérale de Lausanne, Switzerland ⁶CerCo, CNRS, University of Toulouse, France Contact: maya_ro2002@yahoo.com
Schizophrenic patients have strong deficits in backward masking compared to controls. Masking deficits corresponded well to reduced amplitudes in the EEG, particularly, around 200ms after the stimulus onset. We located deficits mainly in the lateral occipital cortex. Are these deficits caused by stimulus induced activity only or a general dysfunction? In order to capture the complex dynamics of brain activity while rest, we recorded 5 min of eyes closed EEG in 27 patients with schizophrenia and 27 age-matched controls. We analyzed microstates, i.e. short periods (~ 100 ms) of scalp potentials which are highly consistent across subjects and recordings. Four microstates played a major role and three of them had different durations and occurrences in patients compared to controls. In particular, these microstates relate to the salience and attention networks. As a speculation, the altered dynamics of the salience and attention networks could be responsible for the masking deficits because the briefly presented target is missed.

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