298 



BRAIN MECHANISMS AND LEARNING 



figure shows that in certain cases the admniistration of ACTH increases 

 the inner inhibition considerably (Lissak, Medgyesi, Tcnyi, Zorcnyi, 

 195S). 



Several examples illustrate that the conditioned reflex method enables 

 us to study the effect of humoral factors on behaviour under objective 

 conditions. Naturally, within those limits it is not possible to analyse the 

 immediate effect of endocrine factors on the central nervous system. In 

 our experiments we started from the assumption that the brain stem and 

 the subcortical mechanisms — which play a fundamental role in the 



i 



5 10 15 20, 25 X 35 W hScm 



^ » 



T 



CpdF CpJB 



Fig. 4 

 Effect of brain stem stimulation upon the corti- 

 coid level and composition of the blood in the 

 adrenal vein of cats. The figure shows marked 

 elevation of hydrocortisone and corticosterone 

 secretion as a result of 15 minutes' stimulation. 



mouldmg of emotional behaviour — are concerned m the integration of 

 conditioned reflex connections and also in the organization of endocrine 

 mechanisms. There are several data to indicate that humoral factors also 

 influence these structures. Experiments with chronically implanted 

 electrodes and electrocoagulation carried out with a stereotaxic instrument 

 on dogs, cats, rabbits and rats revealed a complex circuit of neural 

 processes, which play an important role in the regulation of endocrine 

 mechanisms. 



Without going into the details of the large number of observations I 

 wish to deal only with the main points of our results. It has been observed 



