Performance of the Monkey (Macaca Mulatta) after Two 2500-Rad Pulses of Mixed Gamma-Neutron Radiation.
ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
Pagination or Media Count:
Eighty-five male monkeys maintained in primate restraining chairs were trained to criterion performance on a shock avoidance visual discrimination task. The subjects were then irradiated with either a single 5000-rad pulse or two 2500-rad mid-line tissue dose pulses of mixed gamma-neutron radiation neutron to gamma ratio of 0.4. The second 2500-rad dose was delivered after intervals of 20, 30, 40, 60 180, 270, or 360 minutes. Performance was monitored continuously, and data are reported for animals irradiated with midline tissue doses of 2500 rads, 5000 rads, and 2500 rads followed by 2500 rads. Subsequent to a single 2500-rad irradiation, 75 percent of the subjects exhibited performance decrements. For subjects irradiated with two 2500-rad pulses, the degree of performance decrement was not as great as that observed for subjects irradiated with a single 5000-rad pulse, unless the 2500-rad pulses were separated by an interval of approximately 40 minutes. Despite the decreased behavioral decrement for the animals with fractionated doses, no difference was observed in survival times from those of subjects irradiated with a single dose of 5000 rads. Author