Enhanced memory? Forget about it

UNDER THE MICROSCOPE

As we enter the new, high-tech millennium, some are dreaming of scientific advances not just for living longer, or being healthier, but actually for making us "better" people. First requisite: in-built memory that approaches the speed and accuracy of a computer. Well, such a vision has already taken shape, or rather two possible shapes, both reported recently in the press.

First, there is the chemical version. At the British Association meeting for the Advancement of Science, last September, we were alerted to the idea of memory-enhancing drugs. In the current attempts to combat Alzheimer's disease, it follows that any drug that could be developed to combat it could also, perhaps, be turned to gilding the lily of the brains of healthy people. The target of this pharmacological contrivance would be molecules that have to date escaped the attention of the drug-makers, who normally direct their efforts to modulating the chemical transmission between one neuron and another. Chemical transmission is over in a trice. In contrast, we know that another family of brain chemicals, engaged in a very different enterprise, are far more enduring. These molecules, "cell adhesion molecules", (CAMs) are sticky, sugar-like substances that can play a fundamental role in the long-term formation of connections between neurons. When their CAMs change, the configuration of different neuronal groupings change. It is now thought that by interfering, or promoting, the connectivity between neurons via manipulating CAMs, one might strike at the heart of the memory process.

But there is more to memory than the congresses of isolated neurons. Different brain regions contribute to the memory process in different ways, and there are different types of memory. For example, remembering a skill such as driving is different from knowing the French for "sunshine", and different again from remembering a specific sunny day in Bournemouth with Auntie Flo. Different types of memory, might well use a similar mechanism for reorganising the connections between individual brain cells. But it is not a simple step from a re-configured arrangement between a few neurons to visions of Auntie Flo's hair whipped by a south coast breeze. The steps by which circuits of brain cells configure in different brain regions to contribute to one type of memory or another, is still largely unknown. Any drug that targeted a basic cellular feature of brain adaptation therefore, could not be expected to be specific in the type of brain functions, let alone the type of memories, that might be affected.

Memory cannot in general be divorced from the subjective stance of the individual. Hence the second prospect, that of downloading a lifetime of memories and experiences on to a computer, a BT suggestion dubbed, "Soul Catcher", is unpersuasive. Even the starkest of facts are nested for most of us in memories of events. It is possible in the future that a machine could be stored with all the facts that someone has picked up in a lifetime, but that would hardly constitute the essence of their individuality, their "soul". Auntie Flo and I might have been inseparable during our day in Bournemouth: the bare facts of the excursion would be the same for us both, and could be downloaded: but our memories would probably be very different.

Despite the reverence paid to facts, on their own they are dull fare. It is in making sense of facts where the fun comes in. A small child can be trained to recite a Shakespeare sonnet, but the content would mean little, with few additional facts at their disposal. The more facts we have, the more we "appreciate" the sonnet.

Memory is not an add-on brain accessory but a cornerstone of a holistic and cohesive consciousness. As such, it is hard to see how it could ever be faithfully translated on to a silicon implant, or selectively dissected out with drugs. As yet there is no obvious high-tech short-cut, not even at the conceptual stage, for the next century's high performer wannabe.

! Susan Greenfield is a neuroscientist at the University of Oxford, and Gresham Professor of Physic, London