Measures of Evoked Responses and EEGs during Shallow Saturation Diving

Abstract

Visual evoked responses (VERs) and electroencephalograms (EEGs) were recorded during the course of a long-term, shallow, nitrogen/oxygen saturation dive. Measures were made during excursion dives and at the saturation level prior to and following each excursion. Comparison with a control series, in which bounce dives were made from the surface, revealed that some adaptive changes took place in the VER; complete adaptation however did not occur. Reduction in frequency and amplitude of alpha, in the EEG, also was found during the course of the saturation period.

Visual Evoked Responses and EEGS for Divers Breathing Hyperbaric Air: An Assessment of Individual Differences

“…This result is somewhat at variance with our previous finding of an improvement with repeated testing during a long saturation dive. 6 However, two points should be considered: first, the improvement came after 10 to 12 days of saturation with daily excursions to greater and lesser depths on air; and second, even after this extensive experience, the adaptation was not complete.…”

“…The data are thus in agreement with those from our previous dives; in fact, all of these effects have been reported previously. [4][5][6][7] However, these earlier dives have all employed very few subjects, usually two, and never more than four or five. Furthermore, it was often the case that one subject would respond as indicated above, while another would not.…”

“…This does not mean that EEG changes will not occur under more severe environmental stresses; such changes are well-documented. 6,[16][17][18][19][20]22,23 However, the evoked response is the most sensitive measure of brain functioning for these conditions.…”