world. From this there arose two extremely fruitful trends in the Pavlovian 

 studies: on the comparali\c and on the age-associated physiology of temporary 

 bonds. 



I. P. Pavlov later made a special point of directing the research of a num- 

 ber of his pupils to the problems of the at^e-linked physiology of the central 

 nervous system. These investigations were carried out along two lines: 



(a) a study of the genesis and early forms of conditioned-reflex activity; 



(b) a study of the characteristics of higher nervous activ iiy in old age. 

 The first line was represented by the works of many investigators of the 



Pavlovian scliool. The embryogenesis and early postembryogenesis of reflex 

 activity were first studied and are still being investigated by A. A. Volokhov 

 (1938-1951) and his coworkers (G. A. Obraztsova, Ye. P. Stakalich), I. A. 

 Arshavskiy (1936-1956) and his coworkers (E. I. Arshavskaya, V. D. Rozanova, 

 S. I. Yenikeyeva), and others. 



According to A, A. Volokhov, "the study of the characteristics of nervous 

 activity in the embryonic and early postnatal periods make it possible for us to 

 understand the course of its historical genesis and from this to clarify those com- 

 plex phenomena of nerve functions that take place in the highly developed adult 

 organism" (p. 267, 1953). The general picture of the early ontogenesis of brain 

 activity is characterized by A. A. Volokhov in the following words: "On the 

 basis of the studies that have been made, we can come to the conclusion that 

 the development of reflex activity in ontogenesis is an extremely complex matter. 

 Arising during the early stages of ontogenesis in the form of individual local 

 reflexes, this activity quickly becomes more complicated and transforms itself 

 into generalized forms of reflex reactions. Later on, we observe the conversion 

 of the generalized reactions into specialized reflex acts, which progressively 

 reach that degree of maturity which is characteristic of the adult animal." 

 (See collection: "Teachings of I. P. Pavlov in Theoretical and Practical Medi- 

 cine," Moscow, Medgiz, p. 287, 1953). 



I. A. Arshavskiy's studies later developed into a very interesting trend in 

 ontophysiology, revealing the mechanisms of the age-associated formation of 

 the fundamental nerve processes (according to the orientation of the school of 

 N. Ye. Vvedenskiy and A. A. Ukhtomskiy) and of the regions of the visceral 

 nervous system. Arshavskiy and his pupils are to be credited with more than 

 1 50 experimental studies, which made a substantial contribution to the develop- 

 ment of Soviet age-associated physiology and in particular to that of the onto- 

 physiology of the nervous system. 



The first investigations of the Pavlovian school on the early ontogenesis of 

 higher nervous activity in man were the studies of N. I. Krasnogorskiy on the 

 characteristics of the formation of conditioned reflexes in children (1907-1908). 

 I. P. Pavlov strongly approved of them: "Your experiments are very interesting. 

 It is natural that after analyzing conditioned reflexes in animals we should 

 wish to make an attempt to compare our findings with the phenomena of our 

 internal wcjrld. Then these experiments must be reproduced on human beings, 

 and first of all on children. And when a similarity has been established ac- 

 curately and scientifically, it is then time to compare the phenomena of the 



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