%A Blain-Moraes,Stefanie %A Lee,UnCheol %A Ku,SeungWoo %A Noh,GyuJeong %A Mashour,George A. %D 2014 %J Frontiers in Systems Neuroscience %C %F %G English %K Ketamine,ketamine anaesthesia,EEG,Consciousness,Anaesthesia agents %Q %R 10.3389/fnsys.2014.00114 %W %L %M %P %7 %8 2014-July-01 %9 Original Research %+ Dr George A. Mashour,Department of Anesthesiology, Center for Consciousness Science, University of Michigan Medical School,Ann Arbor, MI, USA,gmashour@med.umich.edu %+ Dr George A. Mashour,Neuroscience Graduate Program, University of Michigan Medical School,Ann Arbor, MI, USA,gmashour@med.umich.edu %# %! Ketamine and EEG %* %< %T Electroencephalographic effects of ketamine on power, cross-frequency coupling, and connectivity in the alpha bandwidth %U https://www.frontiersin.org/articles/10.3389/fnsys.2014.00114 %V 8 %0 JOURNAL ARTICLE %@ 1662-5137 %X Recent studies of propofol-induced unconsciousness have identified characteristic properties of electroencephalographic alpha rhythms that may be mediated by drug activity at γ-aminobutyric acid (GABA) receptors in the thalamus. However, the effect of ketamine (a primarily 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.