Rebound electroencephalographic responses to nitrous oxide exposure in men

Area of Science:

• Neuroscience
• Psychiatry
• Anesthesiology

Background:

• Nitrous oxide (N2O) is known to have potential antidepressant effects.
• Rebound effects in electroencephalogram (EEG) power spectra following N2O administration have been observed in animal studies.
• Understanding EEG alterations during and after N2O exposure is crucial for its clinical application.

Purpose of the Study:

• To investigate if short-term N2O administration triggers changes in delta and theta EEG frequency bands after its withdrawal.
• To compare EEG rebound effects between continuous and repeated N2O administration protocols.
• To explore the relationship between N2O administration and specific EEG frequency power changes.

Main Methods:

• Twenty healthy male participants received 50% N2O either continuously for 20 minutes or in two 10-minute inhalations.
• 19-channel EEG was recorded throughout the administration and withdrawal phases.
• Median-averaged power spectral densities (PSDs) were calculated, and group-level data were topographically plotted.

Main Results:

• EEG transitions during N2O administration and withdrawal were rapid and state-dependent.
• Gamma band power increased during N2O administration, while beta and alpha power decreased.
• Theta band power, but not delta band power, increased after N2O cessation in several electrodes.
• Differences in rebound EEG between continuous and repeated N2O groups were negligible.

Conclusions:

• Short-term N2O administration leads to a significant increase in theta frequency band power upon withdrawal in healthy participants.
• Delta frequency band power did not show significant changes after N2O cessation.
• The observed theta power rebound effect was reproducible with repeated N2O dosing, suggesting a robust neurophysiological response.