PERFORMANCE AFTER IRRADIATION TO THE HEAD 717 



a few days after irradiation. Stahl (1959) indicates that Soviet investigators 

 noted hyperactivity in animals irradiated in the head. Subjects in the AP 

 group have more visual survey after irradiation than before. The present 

 study also provides evidence showing that visual sur\ey is greatly augmented 

 by an unfamiliar environment — our monkeys appeared to be constantly 

 monitoring the setting that contained no monkeys, many investigators, and 

 nothing to hide behind or under. 



Reviewing the syndrome that results from whole body radiation with 300- 

 500 r suggests that some of the changes may be due to radiation efTects on 

 the central nervous system. The salient features of the syndrome include 

 lowered distractibility, changes in posture (Davis et ai, 1958), focalization 

 of attention (McDowell, 1958), relative decrease in initiation of aggression, 

 and relative decrease in manipulation of inanimate objects (McDowell et al., 

 1956). The authors submit that these changes and the changes which follow 

 radiation to the head in the present study are the type of variation that 

 would be expected if central nervous system integrative functions were im- 

 paired. Other facets of the whole body radiation syndrome, such as relative 

 increase in self care (McDowell et ai, 1956) and changes in preferences for 

 foods (Leary, 1955; Davis et al., 1958), are probably related to damage of 

 non-nervous tissue. 



The present study, together with a recent paper by Biryukov (1957), sug- 

 gests that differences between the results obtained by Western and Soviet 

 investigators may be less than heretofore supposed. Both studies showed that 

 after irradiation of the central nervous system, impairment of movement is 

 more prominent than impairment of complex learned responses. The design 

 and statistical treatment of data by Soviet physiologists is vague, but possibly 

 the conditioned response is a more sensitive tool for the detection of inte- 

 grative disturbances of the central nervous system than complex learned 

 behavior. 



References 



Arnold, A., Bailey, P., and Laughlin, J. S. 1954. Effects of betatron radiation on the 

 brain of primates. Neurology 4, 165-178. 



Biryukov, D. A. 1957. Kvoprosu o mekhanizme deistviia pronikaiushchei radiatsii na 

 ner\nuiu sistemu (On the mechanism of action of penetrating radiation upon the 

 nervous system). Eiziol Zhur. S.S.S.R. 43, 636-641. 



Blair, W. C, and Arnold, W. J. 1956. The effects of cranial .x-radiation on reten- 

 tion of maze learning in rats. /. Comp. and Physiol. Psychol. 49, 525-528. 



Davis, R. T. 1958a. Latent changes in the food preferences of irradiated monkeys. 

 /. Genet. Psychol. 92, 53-59. 



Davis, R. T. 1958b. The learning of detours and barriers by monkeys. /. Comp. and 

 Physiol. Psychol. 51, 471-477. 



Davis, R. T., McDowell, A. A., Deter, C. W., and Steele, J. P. 1956. Performance of 



