Closing remarks: an impossible task

Abstract

One of the analogies that has been drawn repeatedly today is that of the record player versus the tape recorder. A record player faithfully reproduces as many times as we wish, but only from a limited variety of originals. As we heard early in today's proceedings, this is the kind of memory displayed by the genetic code and the synthesis of protein molecules. On present evidence, as we heard in the middle part of today's programme, it is apparently also the kind of system by which one out of a large number of antigen producing cells multiplies and increases its production of a specific protein. On the other hand, memory in the nervous system is at first sight like a tape recorder which can take an impression of any pattern and then recall it upon demand! As can be seen more clearly in very simple brains, however, memory in the nervous system is also limited by the range of the sense organs and by the functions or the limits within which the units of the nervous system can operate. We are only just beginning to learn something about the classificatory system of the brain, which is composed of nerve cells apparently having junctions fixed within a narrow range by the 'wiring diagram' of the neural circuits leading into them. Therefore even the highest functions of the brain, which appear to us so infinitely graded and varied, are ultimately limited by the 'fields of view' of the individual nerve cells and by their various combinations. In man, the dependence of the mind upon the mechanisms of the brain is something we hardly like to acknowledge; in lower animals it is more obvious that the repertoire of behaviour, including things that can be remembered, is very much limited by what the units of the nervous system, the neurons, are able to do.