The influence of the respiratory cycle on the EEG.

In order to evaluate the influence of the respiratory cycle on the EEG, we compared the power spectral analysis of the EEG performed by fast Fourier transformation during inspirium and exspirium in 10 healthy subjects. The measurement was performed during spontaneous breathing and then during eupnoe (0.25 Hz), bradypnoe (0.1 Hz) and tachypnoe (0.5 Hz) paced by a metronome. In the course of spontaneous breathing and bradypnoe, there was an increase in the delta power and in the total power in the anterior temporal region during inspirium in comparison with exspirium. The eupnoe was characterized by an inspiratory decrease in the delta power in the parietal region and in the total power in the frontal region. The tachypnoe resulted in a decrease of the beta power in the central region and a decrease of the theta power in the posterior temporal and in the occipital region during inspirium. In comparison of the EEG in eupnoe, bradypnoe and tachypnoe, a decrease of spectral power of all spectral bands was found except for delta during faster breathing frequencies and vice versa with a significant difference which was found mostly between bradypnoe and tachypnoe, less frequently between eupnoe and tachypnoe.