%0 Journal Article
%T Electroencephalographic effects of ketamine on power, cross-frequency coupling and connectivity in the alpha bandwidth
%A Stefanie Blain-Moraes
%A Uncheol Lee
%A George A. Mashour
%J Frontiers in Systems Neuroscience
%D 2014
%I Frontiers Media
%R 10.3389/fnsys.2014.00114
%X Recent studies of propofol-induced unconsciousness have identified characteristic properties of electroencephalographic alpha rhythms that may be mediated by drug activity at £¿-aminobutyric acid (GABA) receptors in the thalamus. However, the effect of ketamine, a non-GABAergic anesthetic drug, on alpha oscillations has not been systematically evaluated. We analyzed the electroencephalogram of 28 surgical patients during consciousness and ketamine-induced unconsciousness with a focus on frontal power, frontal cross-frequency coupling, frontal-parietal functional connectivity (measured by coherence and phase lag index), and frontal-to-parietal directional connectivity (measured by directed phase lag index) in the alpha bandwidth. Unlike past studies of propofol, ketamine-induced unconsciousness was not associated with increases in the power of frontal alpha rhythms, characteristic cross-frequency coupling patterns of frontal alpha power and slow-oscillation phase, or decreases in coherence in the alpha bandwidth. Like past studies of propofol using undirected and directed phase lag index, ketamine reduced frontal-parietal (functional) and frontal-to-parietal (directional) connectivity in the alpha bandwidth. These results suggest that directional connectivity changes in the alpha bandwidth may be state-related markers of unconsciousness induced by both GABAergic and non-GABAergic anesthetics.
%K Ketamine
%K ketamine anaesthesia
%K EEG
%K Consciousness
%K Anaesthesia agents
%U http://www.frontiersin.org/Journal/10.3389/fnsys.2014.00114/abstract