p. K. ANOKHIN 229 



regions ol: the cerebral cortex shows that the specific slow rhythm ot 4-7 per 

 second occurs as a general rule in connection with direct paintul stimuli ot either 

 the sciatic nerve or the skin ot the foot. With other torms ot stimuli, tor instance, 

 stimuli due to tood, one does not get this rhythm. As has been shown by simul- 

 taneous recordings ot EEG and ot nervous impulses ot individual nerve cells from 

 one and the same point ot the brain, the main characteristic of this rhythm is its 

 persistence and its regularity. 



As soon as the rhythm changes even tor a traction ot a second, the cell impulses 

 disappear or diminish. 



We believe that this rhythm originates in the reticular tormation and atter a very 

 short time (o, i-o, 3 seconds) spreads to the corresponding region of the cortex, the 

 parietal and the visual region. I suppose that our disagreements with Dr CIrastvan 

 are basically due to the tact that under normal experimental conditions our 

 laboratory animals are always under some painful influence or in a state ot tear. A 

 specific rh\thm can always appear on the electroencephalogram according to the 

 degree of fear. In normal animals, which are awake, it is very difticult to suppress 

 this rhythm and it can be achieved only after working several months with a 

 pleasant food remtorcement. It mav be that all these conditions were fulfilled in Or 

 Grastyan's experiments. 



I think that in the future we also shall endeavour to bring about conditions under 

 which this rhythm appears more often. 



Galambos. The data from Dr Grastyan's experiments resemble ours closely. I 

 am not sure, however, that the term 'conditioned response' should be applied to 

 these data. Choice ot term is ot course merely a matter of definition, and since a 

 stimulus followed by a reinforcement here yields a changed brain response, the 

 brain event fits the usual definition tor a CR. We view the electrical event, how- 

 ever, as more probably indicating an elementary process in a chain of processes, 

 that, when completed, \ield learning. The phenomenon in question probably 

 indicates that the brain is being prepared for the specific change that will occur and 

 is not the signal of the actual chana:e itself. 



