BEHAVIORAL EFFECTS OF RADIATION ON PRIMATES 725 



Moon, 1956b). On the other hand, we may have some confidence in the 

 findings of loss in learning of fine visual discrimination (acuity), since it has 

 been found by Davis et al. ( 1958) and by McDowell and Brown ( 1958) . 



Monkeys 



If there are uncertainties about the statistical interpretation of a few 

 positive differences among many zero differences in the data for chimpan- 

 zees getting 375-400 r whole body radiation, there are none whatsoever for 

 the data on the cynomolgus monkeys given 2,000 r to the head. 



Method 



Four animals were given gamma radiation from the Emory University 

 Co*^" teletherapy unit, and four were given x-radiation from a 250 kvp therapy 

 unit operated on 30 ma with 0.5 mm of Cu and 1.0 mm of Al filtration. 

 Treatment was given to the sides of the head in a single session which was 

 interrupted at the midpoint to rotate the animal 180 degrees. Total treat- 

 ment required 37 minutes. Doses of 2,000 r were calculated to be midline 

 values, which was approximately 80% of the skin dose. 



Results 



During the first 24-48 hours, no visible reactions were noted, although 

 appetite and activity waned. In the early part of the 3rd week, the animals 

 developed a diflfuse moist reaction of the skin of the head. This reaction 

 required 4 to 5 weeks to completely regi-ess. Towards the end of the healing 

 phase, there was beginning edema, most marked about the eyes, mouth, and 

 inframandibular region (Fig. 4). Death occurred 13-35 weeks after irradia- 

 tion. Shortly before death the animals developed incoordination of gait, loss 

 of placing and hopping reactions, and an exaggerated response to spatial 

 displacement of their body. 



Electroencephalographs taken at various times before and after irradia- 

 tion were variable. However, two effects could be noted. A "glissando" effect 

 started as a moderately regular 25-30 cps wave and decreased in frequency 

 to about 10 cps in 5-15 sec. It appeared only during the first few days after 

 irradiation. The second effect was a homolateral hypersynchrony in which 

 the leads on one side of the head becaine synchronized. The synchrony some- 

 times occurred on one side; at other times the two sides became separately 

 synchronized. The effect appeared only between 3 and 30 days after irradia- 

 tion. 



Within 2 weeks after irradiation, the monkeys were tested on a conditioned 



