Performance of Monkeys before and after 

 Irradiation to the Head with X-Rays* 



Roger T. Davis 



University of South Dakota, 



Vermillion, South Dakota 



AND 



Arnold A. McDowell 



University of Texas, 

 Austin, Texas 



This investigation sought to determine the effects of large focal doses of 

 x-irradiation to the heads of monkeys and is similar in design to three prior 

 investigations on the effects of whole body irradiation on behavior (Davis 

 et al, 1956, 1958; McDowell et al, 1956). The studies explored a wide 

 spectrum of perfonnance to sort out relevant variables. 



Harlow (1953) described two distinct syndromes that result from damag- 

 ing the cerebral cortex of monkeys : the frontal lobe syndrome, which results 

 from bilateral lesions of the frontal lobes, and the posterior association area 

 syndrome, which follows bilateral lesions of the inferior parietal lobule and 

 the lateral surface of the temporal lobe. The former syndrome is charac- 

 terized by a permanent deficit in performance on delayed response problems 

 and a significant, but not permanent, deficit in perfonnance on patterned 

 string, oddity, and double alternation problems. The subjects with frontal 

 lobe lesions frequently refused to work and were inattenti\'e and hyperactive. 



The performance of monkeys with the posterior association area syndrome 

 was permanently impaired on discriminations of form, color, and size of 

 patterns, but temporarily impaired on discriminations between objects. These 

 monkeys were able to solve delayed response problems nearly as well as 

 subjects that did not have brain operations, and monkeys with bilateral 

 lesions of the frontal lobes were nearly as proficient with discrimination 

 problems as controls. 



* These experiments were conducted at the Radiobiological Laboratory of the Uni- 

 versity of Texas and the U. S. Air Force, Austin, Texas, and were supported with 

 funds provided by the U. S. Air Force and the School of Aviation Medicine. The 

 authors were aided in describing technical details by Lorin Logic, Capt., USAF, and 

 Dr. Sidney Kent, University of Alabama Medical School. 



705 



