686 DONALD J. KIMELDORF 



TABLE IV 



Effective Exposure Conditions for Inductance of Conditioned 

 Saccharin Aversion in Male Sprague-Dawley Rats 



Exposure factors Dose rate Total dose 



X-rays, 250 kvp, half-value layer of 2.7 mm Cu 18 r per min 54 r " 



7 rays, Co"*, 1.2 Mev 5 r per hr 30 " 



Fast neutrons, Be(p,n)B, 2 rad per min 7.5 rad " 

 Fission energy spectrum 



• Garcia and Kimeldorf, 1960b. 



»> Garcia el al., 1955. 



■^ Garcia and Kimeldorf, 1960a. 



situation. The question arose as to whether the radiation stimulus could 

 elicit learning in situations not dependent on consummatory behavior. It was 

 decided to determine whether a rat could discriminate as to the place of 

 radiation exposure and whether radiation has motivational qualities sufficient 

 to elicit a learned avoidance of the place of exposure. Exposure to gamma or 

 x-rays was associated with one of two distinctive compartments of a straight 

 30-in.-long alley in a forced trial learning procedure (Fig. 1). One compart- 

 ment of the alley was painted black and had a grid floor, while the other 

 compartment was painted white and had a mesh floor. Prior to the condi- 

 tioning phase, each animal was tested for choice of residence in the alley by 

 removing the barrier between compartments. The cumulative time spent in 

 one compartment was used to separate the animals into groups having a 

 comparable residence preference. During the conditioning phase, rats were 

 exposed to radiation while confined to one of the two compartments. On the 

 day following each exposure, the animals were confined to the opposite 

 compartment for an equivalent time as a sham irradiation procedure. After 

 several such cycles, the partition between the two compartments was again 

 removed, and the animals were given a free choice of residence in the alley. 



Four conditioning sessions with 50 r of gamma radiation at 10 r per hour 

 were sufficient to alter the residence preference in the postirradiation test 

 (Garcia et al., 1957). In contrast to sham irradiated controls, the irradiated 

 animals exhibited a decreased preference for the compartment in which they 

 were exposed, demonstrating that radiation exposure can produce a condi- 

 tioned spatial avoidance behavior. 



Arbit (1959a) has published confiiTnation of radiation-induced spatial 

 avoidance behavior in the rat and has found that autonomic blocking drugs 

 ( tetraethylammonium and hexamethonium ) did not interfere with acquisi- 

 tion of the conditioned behavior (Arbit, 1959b) . Logic et al. (1959) reported 

 that, in the absence of differential cues, intact male rats will spend less time 



