202 



BRAIN MECHANISMS AND LEARNING 



incuts performed by Jasper, Kogan and our own collaborator Polyantsev 

 (Jasper, 1957; Kogan, 1958; Polyantsev, 1959) (Fig- 7)- 



These authors have shown that, when cortical electrical activity is in a 

 state of generalized dcsynchronization, the various individual cortical 

 elements are in absolutely different states of activity. Some of them may be 

 excited, others inhibited, while still others may change the form ot their 

 activity several times during the entire desynchronized state. These data 

 can be understood only in the sense that each activated state of the 



500^^ 



ZOj^y 



vvy^^v^ 



B 



300/«v 



20;iy 



Fig. 7 



A. Simultaneous lead-oft" with the same electrode, i.e. from the same point of the cerebral 

 cortex, of slow EEG activity and impulse activity. The apparent lack of coincidence between 

 the two forms of activity shows a certain independence of the cellular impulse activity on the 

 EEG. 



B. An even more demonstrative lack of coincidence is revealed by leading off^thc two indices 

 from the same point of the reticular formation. Here the EEG does not have the usual desyn- 

 chronization at all but the cellular impulse activity emerges just the same. 



cerebral cortex (according to the desynchronization index) has a corres- 

 ponding system of selective excitation of cortical bonds. It is just this that 

 constitutes the physiological basis for the extensively ramified process ot 

 afferent synthesis. 



This first stage in the formation of the physiological architecture of the 

 conditioned refiex may be represented schematically as in Fig. cS. 



This Figure shows that the afferent synthesis, as a physiological process, 

 draws its energy from the ascending activating influences of the brain 

 stem reticular formation. These influences reacli the cerebral cortex in the 



