34 BRAIN MECHANISMS AND LEARNING 



Dr. Libet and I found that travelling slow waves in the hemisphere ot the frog, 

 starting at the olfactorv bulb, would cross a complete section through the brain if 

 this was made with a sliarp razor blade and if the two halves were accurately placed 

 together. (I do not think neurohumoural agents were involved). Several investi- 

 aators checking in mammals found the spread of epileptic activity was blocked by 

 cutting. Aside from the fact that they were not able to get anything like an 

 equivalent opposition, there was no necessity that this be the same phenomenon. 



AsRATYAN. I would like to ask a question about the same experiment. For how 

 long is It possible to evoke these responses from the head part and the caudal part ? 

 How long does this habit remain? Is it possible to elaborate reflexes on the head 

 part and on the caudal part of the animal after cutting the animal in two and what 

 is the difference m the rate of elaboration and of appearance of learning? 



Gerard. I do not know the answer to the second question. As to the first, it 

 takes about 3 weeks for regeneration and, as I recall, the test was made a month 

 after cutting. Uncut planaria also retained the learning for such a period. 



BusER. Did the author exclude the possibility of peripheral network as happens 

 in many invertebrates, as being hypodermic and distinct from the C.N.S. It could 

 be a diffuse system. 1 • j 



Gerard. I can only answer that work is now in progress with a zoologist and 

 histological tests are being made more extensively. This is perhaps the widest loop- 

 hole; whether there are as yet unrecognized neurones in the tail part of the animal. 



RosvOLD. I was interested in your statement that there is no necessary reason why 

 what happened m planaria need concern us with respect to man's brain or monkey's 



brain ... , i 1 • 1 ■ 



Gerard. May I correct that? I would not say it does not concern us; 1 think it 

 concerns us enormously or I would not have mentioned it. But I do not think it is 

 the whole story. It is part of the story, the substrate on which other mechanisms 



are built. , 



RosvoLD. From a comparative point of view, however, where can one draw tiie 

 line? How close can one make the analysis? If one takes your statement literally 

 could not one always, so to speak, wriggle out of an inconsistency? Simply statmg 

 that the comparison is too remote and, therefore, is hardly appropriate. 



Gerard. I am not really clear as to the question. Is this responsive : I have become 

 a behavioural scientist lately and am m an Institute which devotes itself to be- 

 havioural science. We are concerned with finding the constants in the properties of 

 systems at all levels from molecules to societies. We are often attacked for dealing 

 with meaningless analogies because the details are different in each. I suggest that it 

 is extremely Important to be aware both of the particularities wliich differentiate 

 the one from the other and of the general likeness. When I say, as I do, that an idea 

 in society is in many ways like a gene in biology, and that this is the new disturbmg 

 element which makes social evolution possible as a new gene makes biological 

 evolution possible, I do not mean that male and female ideas mate and that there 

 are mitoses and all the rest of it. This would be arrant nonsense. But it is still useful 

 to see some of the likenesses. If one can in fact get something, assummg that this 

 holds up, which, objectivelv, we would have to call learning, in non-neural cells, 

 even though they have undergone division to form a new nervous system, this is 

 something^vhich I should expect to apply in any comparable situation that could 

 be found In man. Indeed, the reason I brought up these findings is the high prob- 



