646 BRAIN MECHANISMS AND LEARNING 



of each act. It is only by this rule that the individual stages and links of instinctive 

 behaviour can be constructed into an orderly chain of acts, leading to the final 

 adjustment effect for a given animal. 



The point is simply that for learned behaviour the system ot evaluation ot the 

 results of an act done (on which I reported at this symposium) — the acceptor ot 

 action is established as a result of individual experience. Conversely, in the case ot 

 instinctive behaviour, it has been established as a result of a long philogenetic 

 experience and has been fixed by heredity at the time oi the birth of the 

 animal. 



At the present moment our theory is confirmed by new facts and we believe 

 that it is indeed the most acceptable one to account for the mechanism ot the 

 adaptive character of inborn behaviour. 



INTRODUCTION OF THE SECOND TOPIC — SPONTANEOUS BEHAVIOUR PATTERNS 



Thorpe. The physiological origin of patterned nervous discharges is, as I have 

 already indicated, a problem which is fundamental to the study of behaviour. I 

 gave the example of a single cell acting as a pace-maker. I mentioned the possibility 

 of that being so in the cardiac ganglion of the lobster and there are a number ot 

 other instances where a single cell seems to be producing a rhythmic discharge 

 which controls an important and complex piece of behaviour. So there, presum- 

 ably, the whole mechanism for a patterned discharge is contained in a single cell. I 

 would like to ask, then, what you regard as the normal condition for a nerve cell ? 



Do you think of the 'standard nerve e'en' as tending to random discharge when 

 it is not controlled; but subject at times to control by a mechanism which can 

 cither completely inhibit it or else can control it so as to produce a temporal pattern 

 of discharge? That seems to me to be the really fundamental aspect of this problem. 

 But in addition to that I should be extremely interested to hear the views of the 

 various members of this symposium on the extent to which intracranial receptors 

 (and other internal receptors) govern the discharge of nerve cells, hi a slab ot 

 isolated cortex must the lack of discharge be regarded as the normal state or as a 

 special case of inhibition? There are many other similar problems but I hope I 

 have said enough to indicate to you the kind of tiling that strikes me as so particu- 

 larlv important. I hope I have made myself clear, if not I can perhaps add a word or 

 two in the discussion later. 



MORRELL. I would like to raise two questions with respect to the subject ot 

 spontaneous behaviour patterns. I think one of the most striking examples of built- 

 in behaviour patterns is that disclosed by the work of Olds in the self-stimulation 

 experiments, hi those studies it would appear that it is the precise anatomical 

 localization o( the stimulating electrode which determines whether the stimulated 

 point will be rewarding or 'punishing'. One wonders whether these same ana- 

 tomical sites have the same positive or negative significance m the newborn 

 animal as thev do in the adult. It might be interesting to see whether life experience 



