478 WALTER R. STAHL 



that 100 r to the head of fowl in a state of catalepsy would reproduclbly 

 arouse it in a condition of agitation. Elsewhere it has been observed that 

 sleeping animals may be awakened by modest radiation doses. Humoral 

 mechanisms should not be ruled out in these cases, and indirect actions, 

 such as variations in blood-brain barrier, should be kept in mind when 

 interpreting the results. 



Certain types of CR studies are infrequent in the Soviet literature. There 

 seem to have been no tests reported in which radiation was the conditioned 

 stimulus (e.g., a signal of impending shock) which might indicate the lowest 

 perceptible dose or subliminal effects. Work on conditioning of somatic 

 effects is limited. Some older articles indicate the p>ossibility of conditioned 

 leucopenia, hyperglycemia, and other reactions, but the results do not seem 

 to have been confirmed. The possibility of humoral changes would have to 

 be kept in mind with such studies. Radiation has been used as an uncondi- 

 tioned stimulus by Kimeldorf (1961), but in this paradigm it served as 

 an accessory factor modifying the thirst reaction. 



Much interesting speculation is possible as to the basic mechanisms which 

 may be involved in the typical CR and behavioral tests. CR trials typically 

 do not involve learning; the animal knows what the signal means, and the 

 response to the known stimulus is the matter of critical importance. Even 

 in differentiation trials, it is normally not a question of learning, but of 

 discriminating between two known alternatives. Nor do CR studies deal 

 with frequency of response, which is determined by the experimenter. They 

 might be loosely considered to be primarily motivational tests, but with the 

 added important factor of residual influences from the previous elements 

 of the stereotype. The full analysis of correspondence between various types 

 of psychologic tests used in the U.S., Europe, and the U.S.S.R. is a matter 

 that deserves more attention. 



Nervous Mechanism in Radiation Sickness 



Livanov (1957, 1959; Livanov et al, 1960a, b) has been the leading 

 Soviet protagonist of the idea that following radiation exposure there is 

 abnormal afferent activity which leads to some of the well known pathology 

 in radiation sickness. This idea would be considered novel by many Western 

 investigators and has had few protagonists outside the U.S.S.R. The outlook 

 that the CNS play an important role in the production of radiation patho- 

 physiology follows directly from the theoretical Soviet position that disease 

 is the response of the organism to noxious agents in the environment. The 

 CNS mediates such responses and, moreover, attempts to adapt or adjust the 

 organism to the disturbing influence. 



The CNS is thought by many Soviets to analyze the internal milieu in 



