LATE EEG AFTER-EFFECTS IN HUMANS FOLLOWING HYPERVENTILATION .2. A COMPARISON BETWEEN SUBJECTS WITH DIFFERENT LEVEL OF ADAPTATION TO HYPOXIA

The late EEG after-effects following application of a short-lasting ventilatory interoceptive influence (3 min hyperventilation - HV) were studied in humans with three degrees of adaptation: students (ST) with a lower degree of training, professional alpine climbers with a very high level of training (AL 1) and the same subjects (AL2) in a middle position of adaptation i.e. 6 months after an expedition. ST developed late EEG after-effects, consisting mainly in an increase of the beta-2 EEG activity; AL 1 showed very slight changes, while in AL2 the EEG after-effects were intermediate. It is suggested, that a lower level of adaptation facilitates the triggering through HV of processes in the cortical EEG which accompany an improvement of the brain tone.