Saturday, July 01, 2000

Seeking Rosetta

The Private Life of the Brain

By: Graham Cairns-Smith Ph.D.

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In 1798, a young apothecary’s apprentice from Penzance, by the name of Davy, secured a position in Dr. Beddoes’s Pneumatic Institution at Bristol, which was devoted to research into the medical uses of gases. There Davy plunged into the study of nitrous oxide. Experimenting on himself, he discovered that inhaling the gas produced strange and delightful sensations. Some of his friends—including the poets Samuel Taylor Coleridge and Robert Southey—joined in this research, carefully noting the effects of nitrous oxide (laughing gas) on themselves.

What do these long-ago high jinks have to do with Susan Greenfield’s new book, The Private Life of the Brain? Well, in the first place the book says a lot about how chemical substances affect our minds, a problem of neurobiology still largely unsolved. The young Davy had a real talent for chemistry and was soon to move to the new Royal Institution of Great Britain, site of one of Europe’s leading laboratories. From discoveries he made there, he would rise to become the great and celebrated Sir Humphrey Davy, a founding father of electrochemistry. So there is another connection here. Electrochemistry proved to be an essential discipline for understanding nerve action in the 1950s, and is central still in attempts to enter the “private life of the brain.” 

There is yet a third connection. Today, Susan Greenfield is director of the Royal Institution. An enthusiast for the public teaching of science—a tradition going back to Davy and, especially, his protégé and successor, Michael Faraday— Greenfield has research interests in medical neurobiology but is a writer and journalist, too. Characteristically, her new book is highly readable, full of amusing examples and analogies, and spends plenty of time in the everyday world. After a couple of orienting chapters, dutifully setting the current scientific scene, we are reminded of the emotional roller coaster world of “The Child” and then “The Junkie,” and from there move on to chemical control, natural and unnatural, of emotional states of the human mind: 

Throughout our daily lives we blunder between the two extremes of two types of oblivion that can be caricatured by drugs: the dream-like stupor of opiates or alcohol and the vivid sensuality of Ecstasy or cocaine. But in normal drug-free life, our brains will still be in a constant state of flux, sometimes surrendering to sensuality, but often buffering it with the mind. The key final factor linking a subjective state of mind with the press of events in the real brain, might be the degree of neuronal connectivity, of mind, accessed and activated at any one time. 

COMING TO TERMS

Mature sciences have agreed definitions of key words, but science only recently has renewed its attack on the mind/body problem, so do not expect key words here, such as “consciousness” or “mind,” to have clear definitions that we can just look up. Within the vigorous current debate on brains and minds, basic ideas are still fluid and terms have been co-opted from ordinary language, where words may have several legitimate meanings. 

For Greenfield, emotion is the essential attribute of consciousness. For example, she says there can be no such thing as an unconscious emotion. She speaks of “raw feelings” as “the building blocks of consciousness,” and says that “urges are the building blocks of behavior.” The message is clear: Feelings are not to be sidelined as they had been in neuroscience for most of the 20th century. On the other hand, “mind” is “a murky concept.” If I understand her correctly, “mind” encompasses particularly the more enduring part of us, our life-long memories; it is more nearly our “self” than is our conscious, more evanescent part. Thus mind, more than consciousness, differentiates us from others—including our identical twin, if we have one. Greenfield sees this mind as a set of “personalized configurations of brain connections” or, more dynamically, when in action: 

the mind is the seething morass of cell circuitry configured by personal experience and is constantly being updated as we live out each moment. 

Her language here suggests a computerlike explanation in terms of signals, codes and modifiable circuitry, hardware and software. This is the language of science into which we readily can insert discussions of potassium ions, voltage gradients, and diffusing messenger molecules. We will be able to do that only until we come to actual feelings, then we will have to start speaking differently. We will have to be “bilingual,” as Greenfield aptly puts it. Then, I suppose, there appears a kind of mild dualism, a split between the biochemistry and physiology that may go along with feelings, and the actual feelings. 

SEEKING ROSETTA

The Private Life of the Brain has no pictures, but it is full of images. One of the most vivid is of the Rosetta stone. That famous inscribed tablet became the first key to understanding ancient Egyptian hieroglyphics because on it the same text was inscribed separately in Greek, which we understood, and Egyptian hieroglyphics, which at that time we did not. Greenfield suggests we need such a key to understand the brain. This would be, as it were, a translation of the hieroglyphics of emotional states into the formal language of science. 

Perhaps that does not sound so hard. Cannot we translate from one utterly comprehensible language—that of everyday emotional life—full of reasons stated in terms of well-understood feelings and desires, into another language—also well understood—of physics and chemistry? But how can such a thing be done? The extent of the difficulty may be hard to grasp, because what is required is more than a translation from one language to another. We are answering in two radically different ways a question that, in one guise or another, we ask all the time: Why did this happen? In the context of physics and chemistry I might answer, “Because in that way the free energy of the system was reduced,” perhaps adding, “and there is a voltage gradient across the membrane.” But in a different context, in explaining my behavior, I might answer, “Because I thought it would be a fun thing to do”— perhaps adding “of course” to underline how open and transparent my explanation is, how needless to say more. 

Is our real problem that we are too bilingual? We jump from one perfectly sensible way of speaking to another perfectly sensible way, without noticing the absence of a connection between them. We are like a child who handles two languages with equal facility, thinking and speaking in one language or the other, but unaware of dictionaries and literal translations. Although my French is not good, when I am in France I am occasionally stumped for the English equivalent of some word in French. Knowing the literal translation from one language to another is not the same as knowing the languages separately. We seem in that position with the two languages of everyday psychology, on the one hand, and neuroscience on the other. We have no dictionary and no Rosetta stone. 

TIME TO STOP DUCKING

For Greenfield, “the big question that scientists are still ducking” is a central one: How is the actual “feel” of emotions created by the brain? Now, there are fine precedents in the history of science for ducking central questions. Issac Newton put aside the question of the mechanism of gravitational force. Carolus Linnaeus assumed, at least for the sake of discussion, that species are fixed. For 19th century chemistry the atoms of the elements were immutable. There is no harm in tactical ducking, if that is all it is—if it does not become a dogmatic “Thou shalt not ask the question (ever).” For there comes a time when the question should be put, and it looks as if now is the time to ask about the physical nature of “actual feel”—as Greenfield does. 

For Greenfield, “the big question that scientists are still ducking” is a central one: How is the actual “feel” of emotions created by the brain?

A sharp phrase startles us early on: “Learning machines are not the same as feeling machines.” To talk of a feeling machine may sound like science fiction, but I do not think we can avoid concluding that that is what a brain is. Yes it is a learning machine, among other things; but according to an argument given by William James more than 100 years ago, in an essay written in 1879 and titled “Are We Automata?” it is also a feeling machine. I think we should insist that it is a feeling machine as well, and not just a machine producing feelings as a simultaneous, gratuitous effect— not just the other side of the same coin. Our feelings are too appropriate and well connected, too contrived to have arisen other than by a process of evolution through natural selection. The conclusion forced on us by these premises is that we should expect feelings and sensations to be produced and controlled through distinct evolved mechanisms, some class of processes different from dot-dot neural signaling. Making feelings and sending signals are, on the face of it, different. 

This is all speculative, but we should not retreat, baffled. Within Greenfield’s own research area, neuropharmacology, much evidence is emerging that the brain is a “feeling machine.” This evidence comes from studies of the neurobiological control systems of the emotions. We need not understand how the mechanisms work that create our internal experiences to say a lot about how they are controlled. We might not have the foggiest idea how a video recorder works, for example, but know which buttons to press to make it do this or that. 

Some of the control gear for general states of consciousness is in the brain stem. This part of the brain, the most ancient, can be thought of as an upward extension of the spinal cord. Groups of neurons there that may control general states of consciousness are described aptly in the book as “fountains.” I suppose that they also could be likened to complicated syringes with long branching needles whose multiple tips can inject tiny amounts of powerful control substances to specific distant places in the brain. In any case, these control-substance “marinades,” as Greenfield calls them, do not exactly switch things on and off. Rather their presence can be a local enabler; regions of the brain suitably marinated may be activated (or inhibited) more easily. The four key ingredients of the marinades are dopamine, serotonin, noradrenaline, and acetylcholine. No doubt emotional states are among the things these substances help control. Often psychoactive drugs, such as amphetamines or antidepressants, act by enhancing or interfering with these powerful control substances. There is no Rosetta stone here yet, but its discovery may not be far distant. 

We also see that, although there is no special location or seat of conscious experience in the brain, there are places where emotional states are implicated. Greenfield gives us an account of one of the most significant experiments of the 20th century: James Olds’s experiment in which rats had their brains wired up so that by pushing a lever they could stimulate a particular central region, the septal region. They would push the lever until exhausted. Evidently they were having a great time and “a great time” correlated with something going on in the most central regions of their brains.

Maybe pleasurable sensations were being produced there. Or maybe this is where the main switchgear is housed to control production of pleasurable feelings that actually happen more diffusely. 

We are warned by Greenfield, no doubt wisely, not to fixate on the idea that the brain should have special locations, centers, for every function. She sees this as a fallacy allied to the idea that there should be a gene for everything. Well, there are special genes for some things (for example, a function brought about by a particular protein) and surely there is something especially intriguing in looking for a place that is (in some sense) a pleasure center. A subsequent investigation was conducted by Robert G. Heath in 1963 on self-stimulation of a human brain as part of a procedure to combat epilepsy. Electrodes were inserted in different parts of the patient’s brain and wired up to a control box, so when the patient pressed a particular button it would stimulate a particular part of his brain. Sure enough, stimulating the “posterior septum” induced feelings the subject described as “great,” with sexual associations. Self-stimulating other places in the central brain produced other emotional responses, nice or nasty, although not always consistently. The central brain region in question is the limbic system, a crossroads where different parts of the brain fold together. It is an area long thought to be particularly related to the emotions. 

THE EXPANDING/CONTRACTING SELF

From her understanding of the brain, chemical control mechanisms of emotions, and how drugs act on the brain—and from everyday considerations about human nature—Greenfield comes to the book’s central idea, which has to do with the nature of self. 

Greenfield comes to the book’s central idea, which has to do with the nature of self. That idea, first, is that strong emotions abrogate self and, second, that pleasure is the most basic emotion.

That idea, first, is that strong emotions abrogate self and, second, that pleasure is the most basic emotion. Pleasure is a kind of steady state, reminiscent of Sigmund Freud’s notion that the nervous system seeks a state of minimum excitation or rest. Greenfield writes: 

[P]leasure is the most basic of all our emotions: it occurs in the brain when there are no rapid changes in inputs and no significant inherent neuronal connections. It is a state that we are constantly trying to regain, where consciousness is reduced to abstracted senses, to touches and tastes and shadows and softness, and where such sensations are not rapidly replaced by novel ones.

Greenfield’s central idea arose in part through observing that we are least ourselves when greatly enjoying ourselves. At such times, the network of connections that constitutes our self/mind becomes looser and smaller. We worry less. But I hear a protest: Are we not truly “being ourselves” in such circumstances? No, no, the opposite: We are losing ourselves, literally letting go of ourselves. Perhaps much the same basic “feeling machine” switches on in all of us, and our individuality—our self—lies more in our memory-laden cortex. 

Greenfield uses this idea of a self that contracts and expands to make connections with other aspects of normal and abnormal behavior. For example, our mind/self is smaller in childhood; there are fewer firm interconnections among banks of neurons, and they are more evanescent, forming and dissolving more rapidly. As adults we make more, and longer-lived, connections. We have fewer active emotional responses and more worries; more things remind us of more other things. 

Greenfield hypothesizes that schizophrenia, at least in respect to its lack of coherence, is a kind of childishness: 

One sign of schizophrenia is “inappropriate emotion,” where the patient will spontaneously laugh or act frightened in an unpredictable way. The schizophrenic may giggle at a funeral or be overly concerned about a picture on the wall. Such behavior could be, and often is, written off as irrational, much like the fears and laughter of children: inexplicable, illogical responses within the constructs of a reality that most of us have constructed for ourselves ....like the child, the schizophrenic is trapped in the present. 

Schizophrenia often sets in at the end of childhood, as if, perhaps, an adult organization of the brain fails to take a final step within the overall system of controls, and stumbles disastrously. In any case, this condition seems to have something to do with failure of at least the dopamine control system. 

The web of associations that is self also may become more restricted by contracting in time, so everything is in the present. Terror displaces anxiety. There are no more nagging worries if you are terrified by a bungee jump—one happening to you right now. (Or so we are told. Is this really what the director of the Royal Institution gets up to?) It is much the same if you are carried away by music that always works for you, or hungry and eating something delicious like fish and chips done as you like it. 

Thus pleasure and fear are seen to have much in common. But depression is the opposite, according to Greenfield’s analysis. With depression’s tense withdrawal, with far too much going on inside, there is too wide a network of connections, too many negative connections. (I get the impression that when I am depressed my unconscious brain is rummaging to find as many negative things as it can to bring to my conscious attention.) Under Greenfield’s theory, serious clinical depression looks like another fault in overall control. 

Most of us would say that our mind contracts in severe pain, too; it is contracted into the present, able to think of nothing but how to get rid of the pain. But here Greenfield has a paradoxical view. She sees pain as related to depression, which is made more severe by extensive networking, because indeed negative associations have been shown to increase the perception of pain. I find the argument here thin. We have to say that while some emotions are inclined to expand the mind, and others to contract it, there are yet others that do both—expand it in some respects, contract it in others. Pain, for example, may be like depression insofar as it is made worse by extended associations, but pain is also contractive in time. Like pleasure, surely, it causes a concentration on the present. 

THE WETNESS OF WEEPING

In places, I felt that The Private Life of the Brain used the word “emotion” when “feeling” or “sensation” would have been more appropriate—although Greenfield distinguishes between emotions and feelings, at least by implication, when she writes of “the actual feel” of an emotion. That makes it seem as if there is more to an emotion than the wholly brain-centered “feel.” A quadriplegic still has emotional feelings, and this is a neat refutation that Greenfield gives us of William James’s extreme position that emotions are nothing more than the sum of associated peripheral feelings. Anyway, all feelings are no doubt made in the brain, but to insist that at least part of wet-weeping grief is in its wetness—to be distinguished from the more stiff upper lip sort—is to see peripheral elements to an emotion as well as central brain action. We need not go as far as James and say that peripheral feedback is all that an emotion is, but the sensations produced in the brain by this feedback are surely part of it. 

Then there is a host of feelings and sensations that are surely part of consciousness, our conscious awareness of the world—but that may have little to do with emotion. All those more or less neutral perceptual sensations of color, our sense of space, sense of movement, and so on, are feelings and sensations but in themselves may lack the charge of what we normally describe as real emotion. So here I prefer, with William James, to put feelings first as building blocks of consciousness. But these are largely points of terminology. 

FLEEING SCYLLA, KEEPING CHARYBDIS IN PERSPECTIVE

I have a deeper disagreement when it comes to navigating the waters between the monster Scylla and the whirlpool Charybdis. I refer to another nice image, drawn from classical mythology, with which Greenfield describes how in avoiding one fallacy we are liable to sail straight into another. The first fallacy is an old chestnut. Imagine that we are looking at an object. An image of it has registered on the retinae of our eyes. This image is processed and sent to the brain; somehow consciousness occurs. We become visually consciously aware of the object. Who is “in there” to see? Well, nobody, of course, otherwise we are on the edge of an infinite regress: perceivers within perceivers. The buck has to stop, and it has to stop, it seems, in the generation of consciousness itself. Oh yes, Scylla has to be avoided. 

What is implied, I think, in the reality of consciousness, is only that consciousness—having feelings and sensations—exists and has physical causes and effects.

But now Charybdis lies straight ahead, threatening to suck us into another fallacy, something “which might seem so absurd that it is not worth mentioning.” But I mention it all the same, as Greenfield does. In using terms such as “generating consciousness,” we seem to make consciousness into “something tangible being given off, like car fumes, waste products, or bile.” But are we actually caught in the fallacy of making consciousness a thing? I do not think so. Saying that feelings and sensations are real does not seem to me a fallacy at all. Yes, we are properly warned against “a drift into thinking that consciousness can exist as something in its own right,” but we do not have to go that far. What is implied, I think, in the reality of consciousness, is only that consciousness—having feelings and sensations—exists and has physical causes and effects. That it is more like, say, a candle flame, which does not “exist in its own right” exactly—not if we mean that it has some kind of separate, disembodied existence, independent of the candle and the air that continuously generate it. 

So yes, I agree that the fallacy of perceivers within perceivers is to be avoided; and that in so doing we find ourselves sailing in a direction that seems dangerous. But I think Charybdis will turn out to be little more that a stretch of choppy water, although I admit the visibility out there is still very poor. 

A LITTLE JUDICIOUS DUALISM

I will finish by noting another kind of Scylla and Charybdis suggested by Greenfield’s book, although not explicit in it. We are presented with two contrary but attractive ideas, each with much to be said for it, but neither quite right. I refer to naive forms of Dualism and Identity. 

We can agree that René Descartes’s Dualism, dividing existence into distinct mental and physical realms, no longer stands up. Brains make feelings all right, so brains and feelings must belong to the same world. Yet, as I said, there remains some kind of dualism (with a small “d”) up there in the skull—if nothing else, a dualism of understanding. There is a dichotomy between the kinds of brain action broadly understandable in biochemical and physiological terms—where normal physical science can be used in explanation—and that particularly interesting and evanescent part of us, the conscious mind. Surely this latter is also a result of brain action, but here the terms of today’s physical science do not seem adequate. 

We can agree that simple, there-are-two-worlds Dualism is wrong. But so is that favorite 20th century thought-stopper: simple, just-another-way-of-saying-the-same-thing Identity.

We can agree that simple, there-are-two-worlds Dualism is wrong. But so is that favorite 20th century thought-stopper: simple, just-another-way-of-saying-the-same-thing Identity. According to this idea, a conscious state said to cause a particular behavior is just another way of describing the very patterns of neuronal signaling that bring about that behavior, patterns of neuronal signaling for which it is possible to give a complete account in terms of current physics and chemistry. But in such an explanation, the sidelining of feelings and sensations is complete. No reference to feeling and sensation is required. That must be wrong. Actual feelings must not only have physical causes in the brain, but physical effects as well, or they could never have evolved. Natural selection would be unable to operate on actual feelings if actual feelings could have no physical effects. 

Yet we might say that, as with Dualism, Identity has some truth. There is some identifying to be done. The root problem is how activities of atoms or molecules, or cells, or circuits, could ever—at any level—simply and totally equate with events in the private life of the brain, with consciousness. How could one such thing ever be the other? Yet somehow, in some sense at least, this must be so often—all the time, in billions of brains on Earth. Something is going on in all these brains that does not just correlate with feelings and sensations, but is actually the same as feelings and sensations. Greenfield expresses this attitude in her title of the appendix, “The reality of a neural correlate of consciousness,” where she takes a critical look at some recent speculations, including her own, about possible brain processes that might fill the bill. None of the speculations seems convincing yet, but there are many ideas afloat. She ends with the neatest definition of what we should look for here: “A neural correlate of consciousness that is not just necessary but sufficient.” 

I welcome this informed, informal, and lively exploration of life and neuroscience. I think Davy would have approved.

EXCERPT

From The Private Life of the Brain by Susan Greenfield. ©2000 by Susan Greenfield. Reprinted by permission of John Wiley & Sons. 

As the dance gathers momentum, you are aware only of the music and the movements of your body in perfect synchrony. It no longer matters whether anyone is watching, whether you will win a prize. All that matters is the immediate sensation, the flashing lights perhaps, and the certain beat of the music. Even the lyrics of the music no longer have relevance. Your personal inner world no longer matters. You have, literally, let yourself go. 

In a similar vein, at the end of the film Zorba the Greek, the worldly wise yet philosophical Zorba, played by Anthony Quinn, faces total disaster in a project shared with the effete and innocent young Englishman, played by Alan Bates. As the complex edifice for transporting wood to the beach collapses, Zorba, the happy-in-his-skin Greek peasant, slaps his thighs and roars with laughter at the spectacular nature of the failure. With a twinkle in his smile he then extends an outstretched arm to the pusillanimous Bates character and invites him to dance. The film fades as the camera pans back, with appropriate zither music, as the unlikely pair pace out the traditional Greek dance steps, silhouetted alone on the beach. 

When I first saw this film, it was so easy to identify, laugh, and wish, trussed up as I was in my carapace of twentieth-century Anglo-Saxon inhibitions, that I could be a little like Zorba. Although we might not usually dare to dance in the face of disaster, the message is unambiguous: escape from anticipating the future or regretting the past, a luxury afforded only for a moment for our mature human brains. Instead, escape back into an immediate, literally sensual, sensational present, a present normally much more familiar to a child. In extreme cases, the world can be pared right down, as it must be for very young children, to sounds, colors, textures and shapes denuded of all context, of no meaning whatsoever. The entire impact would be derived only from physical properties stripped of all cognitive content. 

For any adult who is not an artist, it is usually hard to unscramble the visual world back into what we actually see, to reproduce on canvas a cascade of colors and shapes. Instead, the all too familiar problem for adults trying to paint an object is that it is shot through with meanings and significance that are virtually impossible for us to disentangle from the literal, abstract, sensory properties of an object. In order to paint literally what one sees, one has to view the world again as a baby might, a daunting task. But in the throes of an ecstatic dance, there you are, back in a meaningless world; and if your consciousness is derived entirely from your senses—only on what is flooding into your ears, up your nose, over your tongue or through your retina—then you must be entirely caught up in the here and now. You are trapped in the ultimate present. 

This is the world, it seems to me, of the dancer at a rave, high on Ecstasy. The external stimuli that keep you in the immediate present are so strong that there is no danger of slipping away inside your mind to your own private, personal world, to a personalized past or future. You are out of control, your movements dictated by the throb of the music, your personality unexpressed, unappreciated, irrelevant.



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Scientific Advisory Board
Joseph T. Coyle, M.D., Harvard Medical School
Kay Redfield Jamison, Ph.D., The Johns Hopkins University School of Medicine
Pierre J. Magistretti, M.D., Ph.D., University of Lausanne Medical School and Hospital
Robert Malenka, M.D., Ph.D., Stanford University School of Medicine
Bruce S. McEwen, Ph.D., The Rockefeller University
Donald Price, M.D., The Johns Hopkins University School of Medicine

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