238 EEG AND EKG OBSERVATIONS 



PRE DIVE, SEPT. 12 IN SEALAB., SEPT. 12 Og 5.5% 



— 'A<| *'^M*^1vv-»~*u#Ji/VW»'^^ 



SEPT. 13 02 4.6% SEPT. 14 O2 4.2% 



^ 10 SECONDS ^ CAL. = 50^V 



Fig. 100. Increase in Alpha frequency of EEC during Sealab II dive period 



The changes in the alpha frequency may be due to acclimatization. They coincided with 

 subjective difficulty with the problem-solving tasks and mental confusion reported by some 

 participants. 



The changes in the EEG coincided also with fluctuation in the gas mixture in the atmosphere 

 in Sealab. The role of O2 in this respect is not clear, but will be studied further. 



In parallel with changes in the alpha frequency, there appeared during the initial dive per- 

 iod, expecially the first 24 hours, a marked increase in paroxysmal activity in the EEG which 

 diminished and disappeared by the 14th of September. This observation needs further volida- 

 tion due to insufficient artifact control. The changes are, however, in conformity with the 

 change one would expect from recordings during O2 or CO2 toxicity and recordings during in- 

 fluence of N2 anesthesia. 



Even with a low N2 content in the atmosphere, the body's normal excretion of N2 through 

 the lungs may be transient impaired, resulting in a transient N2 or narcotic effect. 



The result of the findings indicates that it will be possible to use the EEG to verify physi- 

 ological compatible atmosphere in the habitat at the bottom of the ocean, as well as in free- 

 swimming divers. The problems of the most compatible atmosphere for free -swimming divers 

 are still of major concern. 



INSTRUMENTATION 



The Vesla biological recorder was used for recording EEG and EKG. In cooperation with 

 Scripps Institution of Oceanography (Dr. Snodgrass and Mr. Hill) the instrumentation was mod- 

 ified, and a special high-pressure container was built for the equipment. The housing tolerated 

 seven atmospheres of pressure in salt water, as well as in a helium atmosphere. The Vesla 

 equipment was in the sealed container kept under one atmosphere pressure, thus avoiding any 

 complication from "the bends" in the ink system. 



A standard type S-J airborne EEG electrode v/as used for pre-descent recordings of se- 

 lected members from Teams 1 and 2, as well as for the recordings from the same subjects 

 inside Sealab II during the initial dive period. The same electrodes were also used for the 

 preliminary EEG recording in the decompression chamber and in Sealab II. 



To obtain good records from free-swimming divers in the ocean, and in Dr. Scholander's 

 salt-water tanks, the electrodes and the surrounding skin surface were isolated by a special 



