GENERAL DISCUSSION 653 



One can only safely atiirni that the function of the cortex of the brain is to carry 

 out the analysis and synthesis of the complicated and always diverse information 

 entering through extcro-receptors and intcro-receptors. It should be remembered 

 that this information enters through the sensory organs almost always in a com- 

 plicated form — to use the language of cybernetics : in 'codified' form. 



The deciphering of this code, the distribution of its components to different 

 structures, the comparison of this information with the previous experience of the 

 nervous system and, lastly, as a result of all this, the most important process of 

 afferent synthesis which I discussed in my report — such are the different processes 

 which may take place in the cortex, preceding any learning, i.e. preceding the 

 creation of the elementary conditioned reflex. 



We know now, however, that none of these processes of the cortex can take 

 place without the constantly activating action of the reticular formation of the 

 brain stem and of the hypothalamus. This very fact emphasizes that the whole 

 brain is an organic unit when it carries out a behavioural act, however elementary 

 this act may be. 



AsRATYAN. It seems to me that what I want to say is connected to a great extent 

 with a problem discussed. 



First of all I should like to say somethmg in connection with the problem of the 

 role of brain cortex in nervous activity. Recently we have tried out some investiga- 

 tions in which we studied different inborn reflexes and different neural and humoral 

 regulations of the functions of the organism in chronic experiments, before and 

 after extirpation of the brain cortex in the animals. In most cases we extirpated the 

 entire cortex of the brain. But in cases when we studied the reflexes of paired 

 organs (such as salivary glands, extremities, etc.) only cortex of one hemisphere 

 was removed. In the latter experiments the undamaged side served as a control for 

 the damaged one. All inborn reflexes, i.e. unconditioned, motor and vegetative, 

 were changed to a great extent both in their quality and stabilit)-. Many properties 

 of these reflexes, once changed remained so. We consider it as a proof that cortex 

 takes part in the accomplishment of inborn nervous activity, not only in com- 

 plicated activity but also in simple reflexes. It should be noted that decortication 

 brings also changes in the humoral regulations oi the functions of the organism. 

 We had about forty decorticate dogs and several rabbits, the same result was 

 obtained in all of them. 



Further I would like to say a few words on the influence of constant environ- 

 mental factors on the higher nervous activity. There is sufficient factual and theore- 

 tical material for the hypothesis that this influence may be represented as a tonic 

 conditioned reflex. Reflexes of this type are elaborated in response to such con- 

 stantly acting factors as the time of experimentation, the experimenter, the room 

 and place of experiments, some details in the physical arrangement of the apparatus, 

 etc. It is well known that there are two types of inborn reflex activity: tonic and 

 phasic. We have concrete facts which allow us to divide conditioned reflex activity 

 also into tonic conditioned reflexes and phasic conditioned reflexes. Such tonic 



