The Croonian Lecture, 1965 - The organization of a memory system
The study of memory is unfortunately a difficult and confused subject. Its importance is beyond question, if only because memory lies near the centre of human abilities. Yet there is little agreement even as to the practical results, if any, that may be expected from its study. Education and psychology proceed empirically for want of a general theory of memory, but it is not clear whether such a theory may be expected to come from psychology as studied in man, from experimental study of animals, or from some discoveries of logic, mathematics or engineering. Yet the subject has certainly not been neglected. Immense efforts have been made by psychologists, clinicians, physiologists and workers in other disciplines. In recent years occurrences of various sorts have been reported in the nervous system during learning, from electrical changes, to changes in the base composition of the ribosenucleotides of single nerve cells. In fact there is such a large literature that one cannot avoid feeling that anything that an anatomist may say on the subject will be irrelevant, superficial, naive or worst of all, confusing. I am encouraged to take the risk by the fact that study of the connexion pattern of the nervous system of the octopus has given me a feeling of beginning to understand a little about the subject of memory. To study the material organization behind any subject or problem is surely the basis of a scientific approach. I shall go so far as to suggest evidence for the existence of a unit of memory or mnemon. The suggestion is made with great hesitation and in full awareness of its dangers. The technique of pushing the analysis of the system as far as possible on the basis of the connexion pattern seems to have brought increasing clarification. Recognition of the units is the next further step. Many of those who have so ably assisted in this work will probably not approve of the identification of a unit, still less of inventing a name for it. Many will regard it as a guess, especially since it is not supported by evidence from microelectrodes. Yet perhaps we need to try to identify units, not only as a basis for discussion but in order to find out where to look in our search for the electrical, chemical and other correlates of memory.