[Reactions in the brainactivity during increased carbondioxyde concentration (author's transl)]

A comparative study of two kinds of respiration (normal air and mixed with 4% CO2) was carried out in 8 healthy students. During the three experiments, each one lasting over 120 min, CO2 or air was inhaled using a mask. Blood samples were taken from the fingers, an average increase of pCO2 of 1.9 mm (p less than 0.01) and pO2 of 7.3 mm (p less than 0.01) was found during CO2-inhalation. The ECG and EEG were recorded and reaction times to tone stimuli in a foreperiod reaction time experiment were measured. During CO2-inhalation a clear reduction of the power in the alpha-band was found in frontal, central and occipital region in the order of 23% (p less than 0.05) and 12% (p less than 0.05) and 22% (p less than 0.01). The heart rate interval decreased significantly by 2.3% (p less than 0.05). No significant changes were found in CNV, reaction time and percentage event-related alpha-desynchronization.