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Book Review : Brain Puzzles Science--and Vice Versa

October 28, 1986|LEE DEMBART

Explorers of the Black Box: A Search for the Cellular Basis of Memory by Susan Allport (Norton: $17.95)

Everyone has had the experience of having something on the tip of his or her tongue. The name of a person, for example, or of a restaurant in Honolulu. You once knew it, and you know you know it, but you just can't put your finger on it.

In trying to recall the name, you run through names in your head until you hit on the right one. But how do you know when you've found it? You compare every guess against the right answer until one matches, and then you say, "Aha!" But that means that you must have known the right answer in the first place. But if you already knew it, why couldn't you remember it? You forgot it, but you didn't.

This is a puzzle I have wondered about for years, but I doubt that I will ever hear it satisfactorily explained. To explain it would require that we know how memory works, which is itself a puzzle that has proved resistant to researchers' best efforts. To date, neuroscience can't explain how we remember things, much less how it is possible that we both remember them and don't remember them or recognize that something we hear does or does not match something we already know.

Unknown Mechanism

Questions about the brain are both tantalizing and frustrating. On one level, we have intimate familiarity with our brains (you are using yours right now), but we haven't a clue as to how they do what they do. Somehow, by some unknown mechanism, the millions of cells and neurons packed in our heads give rise to consciousness, to personality and, ultimately, to mind.

Contemporary science takes it as a given that there is a purely physical explanation for all of this. We don't know it, and it may be so complex that we will never know it, but every thought, feeling, emotion, state of mind, perception and memory corresponds to some physiochemical state--and nothing more. We are, after all, just flesh and blood.

But this understanding leads to paradoxes of its own. Is every bit of knowledge stored in a physically discrete place in the brain? If so, there should be a correlation between knowledge and brain size, which there isn't. What's more, learning should be a relatively slow process, requiring the growth of new cells to accept the new data. This is also not the case.

On the other hand, if every bit of knowledge and every thought does not correspond to a physical state in a specific place in the brain, where are these thoughts? What do they correspond to? Is there more to the brain than meat?

There is no satisfactory alternative to the idea that the workings of the brain can be explained by the ordinary rules of biology, chemistry and physics. Researchers recognize that explaining higher brain functions is well beyond them, but in the last two decades they have sought to get a handle on memory and learning. "Explorers of the Black Box" is the story of their work. It is about science and it is about scientists, and it succeeds, more or less, in giving accurate descriptions of both.

Study in Its Infancy

The essential fact about the study of the brain, which Susan Allport, a science writer, makes abundantly clear, is how difficult it is and how little is known. "The search for the cellular mechanisms of learning and memory is still very much in its infancy," she concludes near the end of the book, and she quotes several prominent researchers to the same effect.

But as in much of science, the quest may be as interesting as the elusive answers, and Allport takes us into several biological laboratories to view the effort at first hand. Though her descriptions of the work sometimes bog down, they nonetheless touch off interesting speculations at nearly every turn.

How and where, for example, do nerve impulses get turned into consciousness? Light in various wavelengths impinges on our retinas, which causes nerves to fire, and we perceive sights and colors. How does that happen? Similarly, sound waves strike our ear drums, causing nerves to fire, and we hear sounds. A needle pricks your finger, causing nerves to fire, and you feel pain. Where in the cellular hierarchy do vision, sound and pain arise?

The hunt for answers to these baffling questions involves many neuroscientists who, like all scientists, are subject to all of the human foibles that befall the rest of us. Allport's book describes many of those foibles in great detail. "Scientists are just as biased and susceptible to rhetoric as are politicians, artists and businessmen," she says at one point. She also describes deep-seated feuds and shouting matches that are an integral part of science but are seldom written about.

"I soon came to realize," she writes, "that objectivity and rationality--those long-accepted traits of the scientific mind--were seen better in the way scientists design experiments and collect data than in their views on the research of their contemporaries."

Knowledge From Fighting?

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