ROBERT GALAMBOS 239 



the second place; and ior how it becomes reorganized, fnially, as a resuk 

 of experiences during hfe. If this idea should be correct, the solution of 

 any one of these problems would mean that the answer for the others 

 would drop like a ripe plum, so to speak, into our outstretched hands. 



GROUP DISCUSSION 



Magoun. Dr Galambos's dcnionstraticm that rcinforccniciu leads to a wide- 

 spread generalization of afferent signals within the CNS, together with an incre- 

 ment in their amplitude and configuration, makes the third such report to appear 

 recently. Drs Killam and John found that the central distribution and amplitude ot 

 responses to a series of llashes were increased during reinforcement in avoidance 

 conditioning. Drs Worden and Marsh found the same thing using tones as signals 

 and a food reward as remiorcement. This alteration of the conditioned signal 

 induced by reinforcement may provide the situation which, in Dr Fessard's 

 opinion, is prc-rcquisite for the formation of a novel connection: namely, the 

 elaboration of a stage in which convergence of the conditioned and unconditioned 

 signals can occur. At the Moscow colloquium, Dr Gastaut stressed the importance 

 of subcortical brain mechanisms in this regard, because these then provided the 

 only known sites at which the conditioned and unconditioned signals might con- 

 verge upon common neurones. With the demonstration that a reinforcing stimulus 

 opens widespread regions of the brain to an incoming signal, we need not search 

 tor tocal sites where such convergence might occur, for many possibilities then 

 emerge. The role ot reintorcement, in generalizing and increasing the amplitude ot 

 the responses of the central nervous system to afferent signals, represents an out- 

 standing achievement of recent electrophysiological investigation of the processes 

 ot learning in the brain. 



Galambos. May I add that it was Arteniyev and Bezladnova lo years ago who 

 dealt first with the problem [Artemyev and Bezladnova (1952). Electrical reaction 

 ot the auditory area ot the cortex of the cerebral hemisphere during the formation 

 of a conditioned defence reflex. Trudy Inst. Fiziol. I, 22S-36.] 



Palestini. I would like to know whether you notice any difference in the rate of 

 development of habituation by recording in different sites of the brain. 



Galambos. I cannot give a precise answer. The extraordinary variation in 

 response amplitude encountered during the experiments has thus tar prevented the 

 precise measurements that would be required. 



Palestini. In our laboratory we have observed some difference in the rate of 

 habituation, between the specific and non-specific sensory pathways; the habitua- 

 tion is faster for the non-specific responses. The places we recorded at were the 

 reticular formation, the mesencephalon, the centrum medianum and the non- 

 specific responses in the cortex. We also found that both habituation and condi- 

 tioning are better shown in the slow late potentials. 



Thorpe. I think the suggestion that an investigation of the organization of the 

 'centres' for instinctive behaviour may throw a light on the process ot learning, is a 

 very important one. Often when you are dealing with animals which have fairly 

 elaborate innate behaviour, learning consists chiefly in making a fine adjustment to 

 these innate behaviour patterns, and so in studying instinctive behaviour one often 



