232 BRAIN MECHANISMS AND LEARNING 



Finally, there arc the matters of how different 'perceptions' arise merely 

 because the input energy arrives, say, via the ear rather than the eye, and 

 how it can be that these perceptions become permanently stored as 

 'memories'. The data about the brain needed for dealing scientifically 

 with these last objective behavioural events are meagre or nonexistent, 

 but progress in the development of new and relevant information is 

 obviously accelerating and inevitable. 



II. What is the essential nature of the neuronal organization which 

 makes the innate 'reflex' responses inevitable for the animal; It is not a 

 chance matter that dogs breathe and swallow, and salivate when food is put 

 into the mouth, and withdraw the paw when an electric shock is applied 

 to it. Neither, one must admit, is it accidental or by chance that they learn 

 when exposed to the world about them. As is true of every living animal, 

 dogs come naturally equipped to do things of this sort. There are many 

 such innate behavioural responses displayed commonly throughout the 

 animal kingdom, and in addition patterns peculiar to each species are 

 clearly recognizable. Thus dogs bark, not mew; and they are adapted 

 behaviourally to do many other things not in the repertoire of pigeons and 

 cockroaches. Experimenters on brain function generally assume that 

 comprehensible neural correlates exist for both the species-specific 

 behavioural displays and for the ones which the different species com- 

 monly exhibit. It is unnecessary to point out, however, that while exact 

 descriptions of such behaviour arc available from many sources, satis- 

 factorily comprehensive neural generalizations for dealing with them 

 certainly are not. 



III. What is the new neuronal organization created within the animal by 

 an experience with the world around him; The dramatic commonplace 

 phenomenon we call learning must be explained, it would appear, as a 

 more or less permanent change of the nervous system. An astonishingly 

 large amount of searching has gone into attempts to specify the exact 

 nature of that change, and it is clear that physiologists, rightly or wrongly, 

 consider this process of learning to be of paramount interest and import- 

 ance to an understanding of brain physiology. The scientific analysis has 

 largely proceeded by attempts to describe where in the brain, and when 

 in time, the brain change takes place, and there are several current ideas of 

 the essential features of the process. Furthermore, much new information 

 is being developed, as this Conference will demonstrate. Some ideas seem 

 to be growing in favour while others decline, and it is towards a critical 

 evaluation of both the ascendant views and the classical ones that I would 

 direct your attention in what follows. 



