Visual evoked responses, EEG's and reaction time during a normoxic saturation dive, NISAT I

Three Navy divers were exposed to a normoxic breathing mixture at 7.0 ATA for seven consecutive days. Visual evoked responses (VER's), electroencephalograms (EEG's) and simple reaction time (RT) were measured. Previously reported amplitude decreases in a VER to a flash rate of 1 Hz (VER 1) and to a flash rate of 16 Hz (VER 16) were again found during this dive. The variability of the VER 16 and the latency of the VER 1 also increased during the saturation period. In the EEG analysis, changes in the amplitude of both alpha and theta were found, as were decreases in alpha frequency. The RT task showed a marked elevation of response time at the beginning of the dive period which gradually returned to predive levels. Latency of the VER 160-180 ms component was highly correlated with the changes in RT. The results are discussed in terms of information processing and cerebral dysfunction.