706 ROGER T. DAVIS AND ARNOLD A. McDOWELL 



The syndrome that results from whole body radiation of monkeys is totally 

 dissimilar to those produced by surgical lesions of the brain. Immediate and 

 delayed effects of whole body radiation include changes in relative amounts 

 of self care, unrestricted manipulation and social behavior (McDowell et al., 

 1956), lowered distractibility, lessening of visual acuity, change in posture 

 (Davis et al., 1958), focalization of attention (McDowell, 1958), and 

 changes in preferences for foods (Leary, 1955; Davis, 1958a). 



There appears to be great dissimilarity between results obtained in the 

 Soviet Union and in this country in regard to radiation sensitivity of the 

 central nervous system. Several Soviet investigators have reported changes in 

 conditioned responses of laboratory animals following radiation to the head 

 with relatively low doses (Stahl, 1959). In this country Blair and Arnold 

 (1956) found differences in maze running between nonirradiated rats and 

 those irradiated in the head with high doses of x-rays. Harlow (1958) ob- 

 tained transient, but marked, deficits in the performance of monkeys on 

 complex learning tasks by implanting needles of Co^° in the cerebral cortexes 

 of monkeys. The needles impart a high local dose. 



Methods 



Subjects were 27 male rhesus monkeys given preliminary training, then 

 randomly sorted into three head-irradiated groups and one nonirradiated 

 group. The first experimental group, seven monkeys designated A, was given 

 two 3,000 r doses of x-radiation to the frontal lobes; the second group, six 

 monkeys designated P, received a comparable dose of radiation to an area 

 of the head lying over the inferior parietal lobule and the posterior aspect 

 of the temporal lobe; the third group, designated AP, was treated with the 

 same doses over both the anterior and posterior foci. 



Three patterns of radiation were employed. The first pattern, used with 

 group A, was designed to irradiate the anterior portion of the frontal lobes. 

 The pattern, 2.2 cm wide, extended inferiorly to a line horizontal to the 

 corner of the eye. The intersection of the anterior line of the pattern with 

 the superior midline lay 2.1 cm dorsal to the supraorbital protuberance. 



The second pattern of irradiation, used with the P group, was designed 

 to irradiate the posterior association areas. This focus was 0.9 cm wide at the 

 apex and 2.0 cm wide at the base. The angle of the sloping inferior line was 

 determined by extending a line from the corner of the eye parallel to the 

 zygomatic arch. The posterior line of this focus was fixed by measuring 2.5 

 cm rostral to the anterior aspect of the occipital protuberance. 



The AP group received both patterns of irradiation. 



Dimensions of the patterns and their relationships to external landmarks 



