Low frontal electroencephalographic coherence in neuroleptic-free schizophrenic patients.
BACKGROUND
Electroencephalographic (EEG) coherence analysis is a noninvasive technique for studying corticocortical associations. As there is evidence for a dysfunction of the prefrontal dorsolateral cortex in schizophrenia, we hypothesized to find lower frontal EEG coherence in schizophrenia.


METHODS
EEG amplitude and coherence analysis was performed in 16 antipsychotic-free schizophrenic patients and 16 healthy controls. EEG recordings were done with 19 gold-plated electrodes placed according to the International 10/20 system against averaged signals from both earlobes. Local coherence was computed for 22 adjacent electrode pairs within the hemispheres and interhemispheric coherence for eight corresponding electrode pairs of both hemispheres in the delta, theta, alpha, and beta-I band.


RESULTS
Amplitude and interhemispheric coherence analysis revealed no differences. Local EEG coherence was significantly lower in schizophrenic patients for Fpl-F7 in the delta (p = .001) and the theta band (p = .002), and at F7-F3 in the alpha band (p = .002). In the delta band coherence of Fpl-F7 was inversely correlated to the Positive and Negative Syndrome Scale positive symptoms subscore (R = -.74, p = .014).


CONCLUSIONS
Assuming that EEG coherence can be used to index functional coupling between brain areas under the electrodes, the low EEG coherence in Fpl-F7 and F7-F3 in schizophrenic patients might reflect impaired information processing in the left dorsolateral prefrontal cortex.
Department of General Psychiatry, University of Vienna, Austria.
J
J
Tauscher
P
P
Fischer
A
A
Neumeister
P
P
Rappelsberger
S
S
Kasper
D000328:Adult; D014150:Antipsychotic Agents / Q000494:pharmacology*; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D001330:Electronic Data Processing; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D012559:Schizophrenia / Q000503:physiopathology*
D014150:Antipsychotic Agents