R. W. DOTY AND C. GIURGEA 149 



subcortical pathway is likely to be involved m the production ot this phenomenon. 

 Perhaps pertinent also are experiments which Dr Rutledge and I have been doing 

 using electrical stimulation of marginal gyrus in the cat as conditional stimulus and 

 shock to the foreleg as unconditioned stimulus. If the stimulated cortical zone is 

 circumsccted so that most of the pathways available for intracortical elaboration of 

 the excitation are severed, conditioned reflexes still occur to the cortical conditional 

 stimulus. If, on the other hand, the stimulated cortical zone is undercut for a total 

 length of more than about 8 mm. the conditioned reflexes are lost. They often 

 return, however, after about a month ot training. The critical factors arc not fully 

 determined in the reappearance of conditional reflexes after this undercutting of 

 the stimulated cortex, but it may be that 'U' fibres are necessary. It is also not 

 certain whether that mere passage of time is suflkient or whether it is the retraining 

 which is critical. 



KoNORSKi. Did you try to extinguish these reflexes that you have established 

 and how did you obtain the extinction? 



Doty. Dr Giurgea taught me a lot about extinction. Apparently it is extremely 

 dirticult to bring about a total extinction of a salivary conditioned reflex. 

 Those 'temporary connections' are surprisingly permanent. Hence a technique 

 of 'acute' extinction is used wherein the conditional stimulus is presented 

 as one might expect without the unconditioned stimulus, but also at much shorter 

 time intervals than employed during the establishment of the conditioned state. I 

 objected that this alteration of procedure would not yield a proper comparison so 

 we tried extinguishing by rather long intervals between conditioned stimulus 

 presentations. In Dog Beta we got no extinction in eighty-five presentations. 

 Hence in Monkey i sliown in the film, we used shorter intervals of 1-2 minutes 

 and on the two occasions produced 'acute' extension in which the conditioned 

 reflexes were totally absent to the conditional stimulus and in five or more con- 

 secutive presentations of the conditioned stimulus, although the animal remained 

 alert. Giurgea has also published extinction data on some of his dogs. Our Dog 

 Gamma in which an aversive factor, was present in the unconditioned stimulus 

 showed rapid extinction. 



Anokhin. Much of the recently gathered data points to the possibility of obtain- 

 ing 'conditioned responses' by an association between the most distinct points of 

 the brain. In fact, this trend of thought covers also some of the better-known 

 conditioned reflexes, as the one induced by training with sound and light. 



Yet a question comes reasonably to our mind: what aspect of the activity of the 

 brain, taken as a whole, do such facts reveal ? Dr Doty's interesting experiments may 

 be taken as instances of the brain tissue's ability to act as a specialized substratum, 

 and to establish instant links between any two stimuli which aftect it 

 simultaneously. 



Our team considers that such aptitude proves the capacity of the nervous tissue 

 to unite any separate elements during stimulation. This capacity is the basic 

 physiological ground of any spontaneous conditioned response. But if we assume 

 at the start that conditioned responses are a physiological function of the animal, we 

 must consider them as the outcome of a complex physiological system, leading 

 necessarily to an adaptation process which involves the organism as a whole. 



Dr Doty tells us that he finds it diflicult to draw objectively a difference between 

 the leg-lifting response which he has induced, and the one obtained in the classical 



