750 GENERAL DISCUSSION 



there are definite sensory changes associated with radiation, for example, adaption 

 and changes in taste. To the best of my knowledge, nobody has worked on this 

 problem. On the other hand, I also said at that time that there are some problems, 

 like learning, in the adult animal that seem to me like a dead-end; and all the 

 work since that time simply tends to confirm this. I have one question for Dr. 

 Levinson. In many behavior studies it is necessary to run a conversion operation, 

 that is to study this problem from several viewpoints. We need to have several 

 diflterent tests to get at the basis of the behavioral phenomenon. Dr. Levinson 

 compared the effects of AET on learning and maze retention with animals which 

 did not receive AET and were irradiated. Dr. Levinson, did you use control 

 animals which received AET? It is possible that AET affected, not the radiation 

 mechanism, but rather motivation and other variables. 



BiLLEY Levinson: I think Dr. Furchtgott is wrong in thinking there are no 

 effects of radiation on the adult animal. I believe there is evidence on this from 

 Russian and American sources. In my paper under the zero radiation group were 

 three subject groups: one received only sham irradiation; one received sham irradi- 

 ation and a saline injection; one received an AET injection and sham irradiation. 

 On the acquisition learning task there were no significant differences, the means 

 being almost identical for all three groups. There were some slight differences in 

 the retention test, probably a function of age such as Dr. Kaplan demonstrated of 

 changes over time. I suspect that if an animal is injected at age 2, 4, or 6 days 

 with saline or AET, there is bound to be some effect. The retention test data sug- 

 gests there was a difference between those receiving AET and those receiving saline. 

 It is well known that AET is toxic. Mr. Thomas Graham, of Western Biological 

 Laboratories, found in preliminary results that AET is greatly toxic in fetal 

 animals. I selected a much lower AET dose than recommended, and if studies had 

 been done with higher doses, we probably could have found some toxicity. 



Jack Arbit (Northwestern University Medical School, Chicago, Illinois): I 

 would like to discuss Dr. Harlow's comments about the marked individual differ- 

 ences in obtaining avoidance conditioning, and also pertaining somewhat to the 

 controversy regarding the reproducibility of the avoidance conditioning phenomenon 

 using irradiation as the unconditioned stimulus. We recently have completed a 

 study using Dr. Kimeldorf's spatial avoidance paridigm and x-radiation as the 

 unconditioned stimulus. It was an analysis of variance design, varying the number 

 of cues available as conditioned stimuli, and emotionality of the animals as meas- 

 ured in an open field test by the number of fecal boluses deposited before the 

 conditioning series took place. Those animals who would be called emotional in 

 terms of their open field behavior showed the avoidance conditioning phenomenon 

 with x-irradiation as the unconditioned stimulus in the spatial avoidance design. 

 Those animals who were in the unemotional group in terms of previous behavior in 

 the open field test did not show avoidance conditioning. This may have some 

 bearing on individual differences in animals or on differences in this phenomenon 

 from one laboratory to another. 



John L. Falk (Harvard School of Public Health, Boston, Massachusetts): I 

 would like to comment on a series of experiments done by Dr. Kimeldorf on radi- 

 ation-conditioned taste aversion and radiation-conditioned spacial avoidance. It 



