Memory (psychology)

Despite minor differences, the findings from all four of these models converge on an understanding of the neurobiology of memory formation as involving shorter term phases in which memory is represented by transient fluxes of neurotransmitters and ions across specific synaptic membranes, followed by the rather slower synthesis of CAMs which, inserted into the synaptic membranes, permit novel patterns of connectivity to arise.

This would seem to suggest that the problem of memory was well on the way to being solved at the molecular level. But there remains a substantial gulf between these biochemical and physiological findings and the much more dynamic pattern of memory as being held by fluctuating patterns of activated neurons in widely different brain regions which the imaging studies suggest. Indeed although synaptic patterns are clearly changed during learning, the evidence from, for instance, the chick studies, and others involving the role of the hippocampus in the rat, suggests that over the course of time, memory “traces” migrate and are distributed across many brain regions. Thus the chick’s memory of a distasteful bead may be stored in one region of the brain in terms of colour, in another in terms of size, in yet a third in terms of shape or context of experience. Memories are not discrete—as witness the many ways in which we can try to recall the name of an acquaintance—appearance, when we last met, the first letter of the name, and a multitude of other possible cues. We all use such cues—and so-called memory experts, with seemingly prodigious memories, often depend upon them.

Memory research has come a long way since Descartes, but we are still far from answering St Augustine’s questions. Even if we were to catalogue all the biochemical and physiological changes that occur when we learn the name of a new acquaintance or try to remember what happened when we went on holiday last year, we will still fail to capture the specificities and subjective experience of the memory itself. Whether the new century’s neuroscientists will do better than those of the last in solving that mystery remains to be seen.