40 1 



J. OLDS AND M. E. OLDS I63 



CINGULATE CAUDATE 



Minutes 



Fig. 9 

 Stimulation with very little effect (cingulate and posterior thalamic electrode, left) and mild 

 effects (two caudate points, right). With stimulation in cingulate or posterior thalamus, 

 responding is sometimes slowed, and errors sometimes increase. But learning is not prevented. 

 In two cases with electrodes in the caudate nucleus, results are ambiguous. At the top, the 

 stimulus causes the number of errors to double (thus stimulation interferes with learning) ; 

 but errors are eventually eliminated (thus learning is not prevented by stimulation). In the 

 other animal with caudate electrodes, stimulation sometimes caused such a great decrement in 

 correct responding that it was impossible to tell whether learning occurred or not. In this 

 case, it may also be noted, the decrement caused by electric stimulation seemed to involve a 

 position habit forced by stimulation, so that the animal failed when the left lever was correct, 

 but succeeded when the right was correct. 



parts of the reticular activating system cause no detrimental effects at all. 

 And moderate or ambiguous effects are yielded in the borderline structures 

 such as the caudate (Fig. lo). And this is practically the same map as was 

 obtained for self-stimulation effects (Fig. 2). 



Is it true, then, that the points of positive reinforcement, far from facili- 

 tating learning, actually inhibit it? 



M 



