Brain stimulation in rats exposed to hyperbaric environments.
Six rats were trained to make an operant response to receive brief trains of electrical current to the lateral hypothalamus (self-stimulation). All animals were then randomly exposed to pressures of 4.03, 5.51, 7.06, or 10.1 ATA breathing either compressed air or N2-O2 and 13.1 ATA (N2-O2 only). When the subjects breathed air at pressures of 7.06 and 10.1 ATA, rate of self-stimulation decreased by 32 and 43%, respectively. No differences were observed in rate of response at any pressure when the animals breathed N2-O2 with the partial pressure of oxygen maintained at 0.2 ATA. When an oxygen-nitrogen mixture was breathed at 3 ATA in which the PO2 was similar to compressed air at 10.1 ATA, self-stimulation rate was decreased by 40%; this suggests that PO2 is a critical variable influencing behavior mediated by brain stimulation. Results are discussed in terms of the use of self-stimulation as one tool for better understanding the neuronal mechanisms of behavior as they relate to breathing-gas mixtures at increased pressures.
Ackerman
M J
MJ
Behavioral Sciences Department, U.S. Naval Medical Research Institute, Bethesda, MD 20014, USA.
Spencer
J W
JW
D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant; D006931:Hyperbaric Oxygenation; D007031:Hypothalamus / Q000502:physiology*; D007222:Inert Gas Narcosis / Q000503:physiopathology*; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism; D009584:Nitrogen / Q000008:administration & dosage; D010100:Oxygen / Q000008:administration & dosage; D010313:Partial Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012653:Self Stimulation / Q000502:physiology*
D018377:Neurotransmitter Agents; D009584:Nitrogen; D010100:Oxygen