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--- PVanscoik@ao*.co* wrote: > Dr. Black, > i would love to see some real data - repeat hyperbaric chamber dives > on the same cohort & test scores. are we debating facts or opinions? Peter, Here's some real data, albeit a small study, from the Journal of Undersea and Hyperbaric Medicine 1995 Mar;22(1):41-9 Dissociation of the Behavioral and Subjective Components of Nitrogen Narcosis and Diver Adaptation, by Hamilton K, Laliberte MF, Fowler B (DCIEM): Abstract: We investigated adaptation to nitrogen narcosis by compressing 11 highly experienced divers in a hyperbaric chamber to the equivalent of 54.6 meters of seawater once a day for 5 consecutive days. The behavioral component of narcosis was assessed with a serial choice-reaction time (RT) task, and the subjective component with a global magnitude estimate. Supplementary magnitude estimates were obtained with adjectives describing work effectiveness and body sensations. The results showed that there was no adaptation on the RT task, although learning was evident. In contrast, the global estimate dissociated from RT and showed clear adap- tation by Day 3. The work effectiveness adjectives followed RT and did not show adaptation. Some body sensation adjectives showed clear adaptation, but others did not. These results lead to the conclusion that the anecdotal reports of adaptation by divers can probably be attributed to the subjective rather than the behavioral component of narcosis. Dissociation of these components suggests mediation by different brain mechanisms, and it is speculated that the gamma-aminobutyric acidA/ benzodiazepine receptor complex, which has been implicated in both the anesthetic and anxiolytic properties of agents such as nitrous oxide, may be involved. (end) In other words, there is some degree of adaptation to nitrogen narcosis. Divers think they're better after repeated exposures but that's about it. _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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