Effects of Cranial X-Irradiation upon One-Trial Reversal Learning in White Rats

Abstract

36 young adult male rats were subjected to 0, 500, 1000, or 1500 roentgens of cranial (whole head) X-irradiation. 41 days later they began learning a series of 20 successive reversal problems in an enclosed T-maze with water as incentive. While there was no significant difference between the control and 500-r groups or between the 1000-r and 1500-r groups, the control and 500-r groups learned the problems with significantly fewer errors, in fewer days, and with more single-trial reversals than the 1000-r and 1500-r groups. The data contradict those of previous investigators who found X-irradiation had no effect or actually accelerated learning and retention in rats and monkeys. Positive findings in this study are attributed to: X-irradiation of the whole head, sensitive test of higher adaptive behavior, and better control of motivational effects of radiation sickness.