Hypothalamic self-stimulation in cats exposed to a hyperbaric environment.

We measured changes in the frequency of hypothalamic self-stimulation in cats during their stays in a normal-oxygen nitrogen-oxygen environment under a pressure of 6 kg/cm2. A 200-300% increase in the frequency of self-stimulation was observed during the initial exposure. A depression of the reaction with a subsequent normalization by the third day took place after decompression. The second exposure led to an adaptation of the organisms to the effect of the elevated partial pressure of nitrogen. It is suggested that the changes in the self-stimulation reaction are connected with the "narcotic" effect of nitrogen under elevated pressures.