NeuroImage
November 29, 2019
David T. J. Liley, Suresh Muthukumaraswamy
18 citations
The reduction in alpha-band brain wave power when people open their eyes is explained by increased damping of oscillatory activity, not by changes in neuronal population synchrony as commonly believed. Using time series modeling of EEG data, the authors found that the NMDA antagonist ketamine modifies these damping changes through glutamatergic neurotransmission. The results challenge the prevailing view that thalamus and neuronal population synchronization drive alpha rhythm generation and modulation, suggesting instead that physiological damping dynamics play a key role.
Anesthesiology
February 6, 2020
Andria Pelentritou, Levin Kuhlmann, John Cormack et al.
15 citations
Xenon and nitrous oxide produce different patterns of brain oscillatory power changes, depending on the gas and the recording method. Xenon increased low-frequency delta and theta power only at loss of responsiveness (delta: 208.3%, theta: 107.4% in MEG; delta: 260.3%, theta: 116.3% in EEG). Nitrous oxide increased high-frequency gamma power (low gamma: 46.3%, high gamma: 45.7% in MEG) and reduced frontal alpha power at 0.75 MACawake in MEG (44.4% reduction) and at 0.50 MACawake in EEG (44.0% reduction). The findings show no clear universal features of action for these two gaseous anesthetics, and differences between MEG and EEG must be considered for accurate brain state monitoring during anesthesia.
bioRxiv (Cold Spring Harbor Laboratory)
March 9, 2019
Andria Pelentritou, Levin Kuhlmann, John Cormack et al.
1 citation
preprint
Equivalent stepwise subanesthetic doses of the NMDA-antagonists nitrous oxide (N2O) and xenon (Xe) produce distinct, frequency-dependent changes in cortical oscillatory source power, measured with simultaneous magnetoencephalography (MEG) and electroencephalography (EEG). At the highest Xe concentration (42%, 1.30 MAC-awake), delta and theta band power significantly increased in both MEG and EEG. N2O administration reduced frontal alpha power more strongly than equivalent Xe doses. N2O alone increased MEG (but not EEG) high-frequency gamma power, with occipital low gamma and widespread high gamma rises. These results demonstrate divergent MEG and EEG signatures of dissociative anesthesia.
bioRxiv (Cold Spring Harbor Laboratory)
October 16, 2017
Suresh Muthukumaraswamy, David T. J. Liley
1 citation
preprint
The arhythmical, scale-free brain activity (1/f β) that dominates neurophysiological recordings is dynamically linked to oscillatory alpha rhythms and is systematically modulated by excitation-inhibition balance. Using IRASA to separate arhythmical from oscillatory activity, the authors show that alpha power correlates over time with the high-frequency power-law exponent βhf, and participants with higher alpha power also have higher βhf. Pharmacological manipulations with tiagabine, perampanel, ketamine, and LSD in MEG, and propofol and ketamine in monkey ECoG, reveal consistent effects of excitation-inhibition balance on both high- and low-frequency β exponents.