220 



BRAIN MECHANISMS AND LEARNING 



Stages of the conditioned motor reaction are observed. Whereas in 

 response to the conditioned stiniukis the positional complex is retained in 

 total conformity with its former nature, the local motor act is completely 

 absent. This selective injury to the local component of the conditioned 

 motor act indicates that positional excitations are really of a subcortical 

 origin. (Fig. 14). 



B 



'^^^m^i^'/''^^ 



V. of 

 • limb 



yxfM^^^M^' 



l!*^ 



■iJ H iiwiiiii M iii i iiiiii i iiiiiiiiiiiii Hi Bimmww HHH i i H i ii m iiiiii mi iiiii' 



Fig. 14 

 Comparison of tlic respiratory component of two conditioned reactions — defensive (A) and 



aluncntary (B). 



The question of how a clearly subcortical complex of excitations could 

 acquire a conditioned reflex nature cannot be dealt with at present, since 

 It would lead us away from the subject under consitieration. Here it is 

 important only to note that our various experiments with the oricnting- 

 investigatory reaction have convinced us that the coiuiirioiicd reflex iidtiirc 

 of the subcortical reactions is not primary. It becomes such only after the 

 active interference oi cortical control at the stage of the very strong 

 orientating reflex (Anokhin, 1949; Livingston, 195H; Hernandez-Peon, 



1958, 1959; t'f^/-) (Fig. 15). 



I presume that this part of my report illustrates sufliciently clearly two 

 propositions: (i) the intricate complex c^f the effector excitations of the 

 conditioned reflex is always very extensive and includes the cortex, as 

 well as subcortical apparatus, and (2) this complex can be understood only 

 by assuming the existence of a stage of synthesis of all the afferent in- 

 fluences affecting the animal at the given moment. 



