300 



BRAIN MECHANISMS AND LEARNING 



In addition to these short direct activating pathways influcncins; the 

 pituitary-adrenocortical axis, there is a long circuit, which, with regard to 

 its controlhng effect, is of a modifying and inhibitory nature. Repeated 

 stimulation of the medial nuclei of amygdale and pynform cortex resulted 

 in a change of composition of adrenal secretory products, whose endo- 

 crine manifestations were coupled with marked sexual hyperactivity in 

 the post-stimulatory period (lordosis, copulative activity in females and 

 copulative activity, priapism in male cats and dogs). 



m 



^ 



.-S^ 



^ 



O 



•o 

 ■SO 



m 

 w 



50 



w 



50 

 20 



i 



I 



^ S iZ 16 20 2h 28 62 56 W ^hcm 



S 



^ \) \) VI 



CpdF 



B A 11' OH proaesterone 



Fig. 6 



Shows the appearance of i i-hydroxyprogesterone in the blood of the adrenal vein after 

 stimulation of medial part of amygdale and pyriform cortex ot cats. 



In female ovaricctomized cats we were not able to elicit the above- 

 mentioned endocrine and behavioural changes which permit an insight 

 into the complex mechanism induced by stimulation of area pyriformis. 



In contrast to the stimulation of archistriatum (amygdale) which can 

 modify adrenocortical activity and somatic behaviour through the pitui- 

 tary-gonadal system, we found an inhibitory influence of hippocampal 

 stimulation on the stress mechanism and in some extent on somatic 



