Neuroscience

In Search of the Lost Cord: Solving the Mystery of Spinal Cord Regeneration by Luba Vikhanski (Joseph Henry Press) is a scientific detective story, the stuff of science fiction en route to science fact. People trapped by the limitation of paralyzed limbs, rendered useless by devastating, catastrophic injuries to their spinal cords, may one day walk again. If the research is successful . . . if the scientists hit on the right strategy for approaching the problem, we may yet see miracles happen.

In her new book, science journalist Luba Vikhanski profiles the rapidly developing field of spinal cord injury research. She explains the field’s greatest scientific challenges and introduces us to the pioneers who are working toward what would be a startling breakthrough. Perhaps the most riveting aspect of this international effort is the fact that each of these scientists is approaching the problem in very different ways. In the worldwide race to claim the prize of a cure, we witness a drama in the making.

Who will cross the finish line first? Will it be the Swiss scientist Martin Schwab, who has actually managed to heal spinal cords in rats and has restored their ability to walk? Will it be Wise Young, a Rutgers scientist who is pinning his research hopes on drug therapies? Or could Lars Olson of the Swedish Karolinska Institute hold the key to success in his efforts to construct a bridge of slender nerve filaments to connect a once-severed spinal cord? His rats are already flexing their legs.

These scientists, and others with unique and creative approaches of their own, have dared to tackle this seemingly unsolvable problem of spinal cord regeneration. Like all major medical and scientific breakthroughs, the “Eureka” moment often seems obvious in hindsight. Perhaps we’ll have the same perspective when the puzzle of spinal cord regeneration is solved and the nerves are indeed healed. Until that time, there’s a race to the finish line, and suspense is building. In Search of the Lost Cord is a trackside seat.

Late on a June afternoon in 2000, Roy Holley rounded the bend of a twisting Rocky Mountain road to discover the crumpled remains of his daughter’s car. He was to learn that 18-year old Melissa had suffered a crushing injury to her spinal cord, leaving her completely paralyzed and without sensation below her mid-chest line.

A year later, a team of doctors made a stunning announcement.

An experimental procedure involving the injection of immune-system cells directly into Melissa Holley’s crushed spinal cord resulted in the recovery of movement in her toes and legs. Although Melissa isn’t walking yet, there is now hope that she may indeed rebound from an injury so devastating that her doctors had ruled conclusively that the destruction of her spinal cord was “complete”—a verdict that has historically left its victims paralyzed for life.

In Search of the Lost Cord is award-winning science writer Luba Vikhanski’s fascinating chronicle of the quest for such a cure. The author takes the reader on a journey around the world to laboratories in Spain, Sweden, Israel, Canada, and the United States, where talented researchers have defied the odds and tirelessly pursued the regeneration of the spinal cord. For decades career-minded scientists have avoided this field entirely because the goals were considered so hopeless. Yet Vikhanski—in gripping prose that brings life to both the science and the scientists’ struggle—shows how a small number of dedicated individuals learned from each other’s successes and failures to finally make hope real. The resulting international effort to restore function to the severely injured spinal cord is on the verge of a breakthrough.

Some day, and perhaps not so long from now, Melissa Holley, and others like her, may walk again. In Search of the Lost Cord is the remarkable and compelling story of science history in the making.

Philosophy and the Neurosciences: A Reader edited by William Bechtel, Robert S. Stufflebeam, Jennifer Mundale, and Pete Mandik (Blackwell) Philosophy and the Neurosciences is the first systematic integration of philosophy of mind and philosophy of science with neuroscience research. As philosophers have come to focus more and more on the relationship between mind and brain, they have had to take greater account of theory and research in the neurosciences. Likewise, as neuroscientists have learned more about cognitive structures and functions, their investigations have expanded and merged with traditional questions from the philosophy of mind. By introducing key themes in philosophy of mind, philosophy of science and the fundamental concepts of neuroscience, this text provides philosophers with the necessary background to engage the neurosciences and offers neuroscientists an introduction to the relevant tools of philosophical analysis. Study questions, figures, and references to further reading are provided in each chapter to enhance the reader's understanding of how philosophy and the neurosciences are related in their exploration of the human mind.

Neurons and Networks: An Introduction to Behavioral Neuroscience by John E. Dowling (Harvard University Press) excerpt: As a separate but integrated area of inquiry, neuroscience is a relatively new field. It is derived in large part from the merging of three quite separate disciplines: neuroanatomy, which focused on the structure of neural tissue and nerve cells; neurophysiology, which investigated how neural tissue and nerve cells function; and neurochemistry, which was concerned mainly with the kinds of substances found in brain tissue. Prior to the 1960s these fields were centered mainly in separate departments in medical schools, although the study of nervous systems, particularly their comparative aspects, could be found in departments of zoology and biology in colleges and universities. But there was minimal communication among researchers in the separate disciplines; each moved steadily

The beginnings of an integrated field of neuroscience came about in the early 1950s, when two new techniques were used to study neural tissue: electron microscopy (in neuroanatomy) and intracellular electrical recording (in neurophysiology). Electron microscopy enabled us to see for the first time what is inside nerve cells, while intracellular recording allowed us to record electrical responses generated in single nerve cells. These two techniques led almost simultaneously in the early 1950s to the discovery of small vesicles within nerve terminals and to the realization that small, discrete electrical responses occur in a nerve cell when it receives input from another nerve cell. These observations would lead to important advances in our understanding of the brain.

It had been known for nearly a century that the brain is made up of billions of individual nerve cells that communicate at specialized junctions called synapses, and it had long been supposed that understanding the nature of these synaptic interactions is the key to learning how the brain works. But progress in understanding synaptic mechanisms was slow. Early in the twentieth century investigators first suggested that nerve cells communicate at synapses by chemical means. They proposed that nerve cells release chemicals that excite or inhibit the receptive cells. Not until midcentury, however, was this theory universally accepted-but the details of the synaptic process remained largely unknown.

The discovery of small vesicles in nerve terminals adjacent to synaptic junctions suggested that the chemicals released at synapses are stored in these vesicles. Moreover, it was realized that the small electrical responses in the postsynaptic cell were related to the released chemicals: the contents of one synaptic vesicle caused a quantal electrical event. These findings immediately linked neuroanatomy and neurophysiology. The anatomical discoveries provided a plausible explanation for the physiological findings, while the physiological findings indicated the function of the newly visualized anatomical structures.

What came next was an explosion of activity that cemented the bond between neuroanatomy and neurophysiology. For example, once the sites of synaptic interaction between nerve cells could be recognized, neuroanatomists began to work out the wiring patterns among nerve cells. The beginnings of an integrated field of neuroscience came about in the early 1950s, when two new techniques were used to study neural tissue: electron microscopy (in neuroanatomy) and intracellular electrical recording (in neurophysiology). Electron microscopy enabled us to see for the first time what is inside nerve cells, while intracellular recording allowed us to record electrical responses generated in single nerve cells. These two techniques led almost simultaneously in the early 1950s to the discovery of small vesicles within nerve terminals and to the realization that small, discrete electrical responses occur in a nerve cell when it receives input from another nerve cell. These observations would lead to important advances in our understanding of the brain.

Neurochemistry was also advancing at this time, particularly in the search for and identification of the substances released at synaptic sites. But close links between chemistry and anatomy-physiology were not forged until the 1970s, when researchers realized that two kinds of substances are used to communicate information in the brain: neurotransmitters, which lead directly to the excitatory or inhibitory electrical responses of nerve cells, and neuromodulators, which exert their effects on nerve cells by modifying the cell's biochemistry. Neurotransmitters mediate fast information processing in the brain, whereas neuromodulators appear responsible for mediating slower, longer-lasting changes in the brain. Memory and learning, for example, are thought to be initiated by the action of neuromodulatory substances.

After the integration of neurochemistry with anatomy and physiology, the term neuroscience came to the fore-the term now generally used for the study of the brain. In neuroscience laboratories, anatomical, physiological, and chemical experiments are done side by side, often by the same investigator. At the same time neuroscientists are being joined by psychologists and computer scientists as the field turns toward questions of higher brain function.

The Quantum Brain: The Search for Freedom and the Next Generation of Man by Jeffrey Satinover (Wiley) a look at the convergence of brain science, biological computation and quantum physics, and what it implies about our minds, our selves, our future, even God Do we really have free will or do we just imagine we do? Do we create our own destinies, or are we merely machines? Will the machines we are now making themselves have free will? These are the fundamental questions of The Quantum Brain. To answer them, psychiatrist, researcher, and critically acclaimed author Jeffrey Satinover first explores the latest discoveries in neuroscience, modern physics, and radically new kinds of computing, then shows how, together, they suggest the brain embodies and amplifies the mysterious laws of quantum physics. By its doing so, Satinover argues we are elevated above the mere learning machines modern science assumes us to be. Satinover also makes two provocative predictions: We will soon construct artificial devices as free and aware as we are; as well as begin a startling re-evaluation of just who and what we are, of our place in the universe, and perhaps even of God.

Excerpt:

The Quantum Brain is the story of a revolution that will transform our world and ourselves, one that already has drawn together neurobiologists, psychiatrists, computer scientists, physicists, and mathematicians in an unprecedented competition coordinated more by sheer excitement than by plan. The competition has two interdigitating goals: to achieve an ever more precise understanding of—hence control over—the human brain and to create ever more powerful synthetic brains. We are now approaching both goals with increasing speed, as the race to reach one goal supercharges the race toward the other. We can now see more clearly that both competitions ultimately lead us into the mysterious world of quantum mechanics.

When the dust settles, this revolution will, of course, bring about huge advances in science and technology. Scientists at the Massachusetts Institute of Technology and elsewhere, for example, are already planning for a forthcoming Internet that functions as a single, worldwide quantum computer. But the ideas that allow for such a technology represent a revolution in our understanding of ourselves, of life in general, even of God.

ENLIGHTENMENT

Our search to understand the brain has proceeded as has all scientific thought since the Age of Enlightenment: It presumes that there is nothing in the brain (indeed, nothing anywhere in the universe) that is more than machine. Neither brain nor mind is anything spiritual or insubstantial; there exists in man no soul, only a collection of physical objects affecting each other via impersonal forces. The unfolding states of these objects, however complicated, are completely determined by whatever states they were in previously: universal billiards without players, payoff, points—or point.

Set in motion once for all time at the Big Bang, particles that later happen to comprise a human brain have no freedom of action whatsoever, neither individually nor as an ensemble. That we think of ourselves as "free," as having "minds" capable of "choosing," indeed, that we even think we think: illusion all. What we like to call "will" is at most the inevitable by-product of mechanical interactions of the brain's parts. Illusory "mind" can influence neither what the brain does nor the bodily actions the brain sets into motion.

Poets, mystics, philosophers, and theologians have always insisted that this game of universal billiards has both players and purpose—and their followers have ever fought over who and what these are. But ever since the Enlightenment, science has argued that it is both impossible and unnecessary to know whether the opening break was that of a cosmic Minnesota Fats of incomparable foresight or of a merely comic amateur. In either case, the cue stick lies long abandoned; the player long gone from the shot, the table, the game. The pool hall itself is empty, though the neon lights burn on. In the words of Harvard astronomer Margaret Geller: "Why should [the universe] have a point? What point? It's just a physical system, what point is there?"

For all the millennia that human beings looked at the universe as guided, purposeful, and pregnant with meaning, its operations remained mysterious. But once science arose, the universe swiftly began to yield its secrets. By shifting so wholeheartedly to this point of view that not even life, not even human life, is exempted, science has found itself able to break open even seemingly impenetrable mysteries of mind: learning, intelligence, intuition—all of these can now be extensively understood in wholly mechanical terms. What's more, they are being mimicked by man-made machines. More powerfully than has any prior scientific discovery, the unlocking of the brain seems to confirm the scientists' hypothesis that everything—the mind of man included—is machine.

Steven Weinberg, winner of the 1979 Nobel Prize in physics and an eloquent spokesman for the machine point of view, put it this way: "The more the universe seems comprehensible, the more it seems pointless." And more: "It would be wonderful to find in the laws of nature a plan prepared by a concerned creator in which human beings played some special role. I find sadness in doubting that we will . . . And it does not seem to me to be helpful to identify the laws of nature as Einstein did with some sort of remote and disinterested God. The more we refine our understanding of God to make the concept plausible, the more it [too] seems pointless."

The idea that the entire universe is nothing more than a "physical system"—that is, a machine—unfolding mechanically according to rigid and immutable laws began as the radical heresy of a few brave minds. With this idea as their starting point, they and their followers began to experience an uninterrupted string of successes. There is not a single working medical device or treatment, not a vehicle, not a communications technology, not an industry that isn't based on this assumption. Between the age of Galileo and the end of the twentieth century, the once-radical heresy had become a worldview shared by billions (whether aware or not). So far has this transformation gone that here in America, for instance, where it was once a requirement that a professor in any department in any reputable university be a "man of God," it is now rather an embarrassment should he admit to taking seriously such a thing. The renowned evolutionary zoologist, Richard Dawkins, maintains that anyone who believes in a creator God is simply "scientifically illiterate." By the end of the nineteenth century, scientists believed they had uncovered almost all of the fundamental laws of physics. These laws were all purely mechanical, and out of their mechanical interactions (however complicated-seeming and difficult, in practice, to track these may be) arises every phenomenon we experience at every scale. Living matter itself was understood to be nothing more than an especially complicated factory of molecular machinery.

Needless to say, there were (and are) a great many people who found this vision of reality a horribly bleak one. Most understood little enough about the subtleties of the mechanistic point of view, and of scientific method, to allow them to dismiss it without ever seriously experiencing the power of its claims. But there were a few who did indeed understand its power and hoped that eventually it would somehow be proven wrong. They hoped, in other words, that one day scientists themselves might discover a fundamental law of the universe that was not wholly mechanical but in some sense "free." These hopes were rekindled with the emergence of the strange theory of quantum mechanics.

QUANTUM LONGINGS

While it is true that at the turn of the last century almost every fundamental physical phenomenon seemed understood, three did resist explanation by the mechanical view of nature. Of course, none of them seemed to have any larger implications about the nature of man, of free will, of life, of God. And to the man in the street they were utterly uninteresting:

Why does a radioactive nucleus spit out an alpha particle now but not then, and completely at random? (The mechanical view predicts that there ought to be some kind of regular, internal clock that orders its departure, but there is none.)
If you heat up any completely black object—like a bowling ball—why is the heat it radiates back at you invisible, and why is it always heat, that is, "infrared radiation," and always in the exact same distribution of infrared "colors"? (The mechanical view predicts that the hotter the bowling ball, the more the radiated energy should be as visible light, starting with red, running through the rainbow, and then into the ultraviolet. Note: We're not talking about making the ball so hot that it glows by itself!)
If you shine light on metal, it will eject electrons—" the photoelectric effect." If the color is right for the metal, or more toward the blue, an electron will always be spit out at once, no matter how faint the light. But if the color of the light is more toward the red, it doesn't matter if the light has the intensity of an industrial laser—an electron will never be spit out. Why? (The mechanical view predicts that as long as you shine enough light—and there ought to be some minimum—it shouldn't matter what the color is or how intense is the beam.)

These do not seem like earth-shaking quandaries. But when scientists finally did figure out the answers, most of them received a tremendous shock and some had an equally tremendous hope. For the theory that solved these dilemmas—quantum mechanics—gave the following Delphic answers:

Nothing at all in the physical universe "causes" an alpha particle to jump out of its nucleus when it does. It just does so, "whenever it wishes." Not only that, it gets out in spite of the fact that the barrier keeping it in is too high for it to get out at all. Were the world really as tidy as scientists had thought, the alpha particle ought no more ever be able to get out of its nucleus than could a prisoner in a cell on Alcatraz instantly appear in San Francisco.

Hot, black bodies are black because energy comes in discrete units. This doesn't sound weird, but it's akin to discovering that time only comes in units of hours so you couldn't ever experience or measure time passing during an hour; it would just jump from one hour to next.

A beam of the right color light, no matter how faint, instantly generates electricity in a metal because, even if the light is spread out like energy, it is at the same time a billiard ball–-like particle that knocks an electron out of its orbit. But if the color is wrong and the energy of the light is too low, it doesn't matter how many particles you throw at the metal, none of the electrons will budge—like throwing thousands of Ping-Pong balls at a bowling ball stuck in a rut.

In the century since it first appeared, quantum theory has created many new dilemmas, solved those dilemmas as well, and all in all proven itself the most successful theory in the history of science. In doing so, it has demonstrated that at its foundation, matter itself does not behave like a machine at all. The very mechanical premises upon which science has been built may be overturned by science itself. This has given some hope that we may find in quantum theory an exit from the dead-end trap of a world that "has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil and no good, nothing but blind, pitiless indifference," in the words of the eminent evolutionist Richard Dawkins.

Some of these quantum exits take the strange phenomena found at the quantum, subatomic scale and apply them wholesale to human life because of the analogies one can make between, for example, the freedom of choice we believe that we, as people, have and the "freedom of choice" that electrons apparently have. Most serious scientists reject such analogizing because they know enough about how quantum mechanical effects "scale upward" to be convinced that any and all quantum weirdness is long gone by the time we are dealing with aggregates of gazillions of particles large enough to form people.

But as modern biological science has penetrated down into the subcellular levels of living matter, and in particular those that constitute the brain, it has indeed begun to encounter the eerie quantum effects that have confounded physicists for a century. These effects are not analogies, they are real, and, as we will see, it is only by considering them that we can begin to understand the building blocks of life. That this is so is not yet widely known to most biologists, but it soon will be. And it will have a dramatic effect on both science and on scientists.

At the subcellular level, matter itself actually looks and behaves (in the words of one physicist) "more like a thought" than like the cogs of a machine. Nothing in the world that causes the particle to jump, discovered the first quantum mechanics. But the first premise of science is that everything happens solely as a result of causes in the world. "If we are going to stick to this dammed quantum-jumping," complained one of its founders, "then I regret that I ever had anything to do with quantum theory."

Furthermore, if subatomic particles can freely choose to come and go as they please, then perhaps old-fashioned claims as to our own nonmechanical nature aren't so archaic after all: Suddenly, the machinery of brain might prove the illusion, mind and will a more foundational reality. A number of the founders of quantum mechanics wondered out loud whether the ancient mystics might not be right after all: Perhaps there is a Player. Standing apart from the mere "physical system," he everywhere spins the shots, making everything happen this way rather than that. Wolfgang Pauli thought so: Tongue not wholly in cheek, he simply referred to the so-called exclusion principle, a cornerstone of modern physics and chemistry, as "God."

It turns out, however, that the amount of absolute "freedom" individually available to the bits and pieces of the universe is unbelievably tiny. It amounts to much only on the scale of atomic and subatomic particles. At any scale large enough to be of concern to human beings (e. g., for stuff the size of viruses), the net effect of all that freedom is zero—it just cancels out. Electrons may jump from here to there for no reason whatsoever, but planets don't; nor boulders; nor grains of sand; nor we.

But now the revolution: It appears possible that instead of averaging freedom away as usual, the human brain, itself a machine, has nonetheless evolved a unique structure that harnesses subatomic "choice," concentrates it, and amplifies it upward, scale by scale, taking advantage, as we will see, of the strange facts of "chaos." Of all things, it's the machine in our head that lets us transcend our own mechanicality.

Our brains are, if you will, "quantum computers." But they are not of the sort now making headlines. Subtle quantum effects in the brain afford us a capacity we would not otherwise have, yet to make maximum use of such effects our natural brains are now designing even better synthetic ones. These employ quantum principles directly, not, as in the human brain, in subtle and nearly invisible fashion. Some of them will be set free to evolve themselves in Darwinian fashion, hardware and all. But if quantum processes are the source within the human brain of genuine thought—as also of genuine will, intention, and choice—then the quantum computers we are on the verge of designing (or whose evolution we are at least facilitating) may turn themselves into genuine sentient beings. They may have as much intelligence as we have, quite possibly more: There are severe limits to how much quantum weirdness the human brain may employ (and of which sort—a distinction we'll make clear); the limits on how much a synthetic brain might employ are far less severe. Vast, synthetic, self-evolving, superintelligent, and completely sentient computers must surely sound like pure science fiction, but they are not. Nor are they from some far distant future.

Furthermore, in the human brain, the amplification of quantum freedom happens via means that preserve the appearance, at our day-to-day scale, that we, and our universe, are completely mechanical. All this is terribly confounding to philosophers who seek to understand the world, and human life, in terms with which they are already familiar. But to really understand where science is leading us may well require a great deal more intellectual discipline and envelope-pushing than rock-ribbed reductionists, tradition-minded theists, or New-Age hand-wavers are comfortable with: "Our imagination is stretched to the utmost, not, as in fiction, to imagine things which are not really there, but just to comprehend those things which are there," in the words of Richard Feynman, the renowned theoretical physicist. Many scientists speak of a "crisis" brought about by the implications of quantum mechanics and look for something cleaner, more truly a "mechanics," to replace it and to restore the austere reductionism of the Enlightenment. Not a few see confirmation of ancient religious notions. But there are some who see something wholly new, fraught with both fantastic opportunity and terrible risk. If human nature remains true to its history, we may expect both the risk and the opportunity to be realized, with much gain and much loss. In any event, our understanding of who we are, where we came from, our standing in the greater scheme of things, and where we're going, all looks soon to suffer a dramatic change.

--From The Quantum Brain : The Search for Freedom and the Next Generation of Man, by Jeffrey Satinover. © February 2, 2001

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Review Essays of Academic, Professional & Technical Books in the Humanities & Sciences

Neuroscience

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Review Essays of Academic, Professional & Technical Books in the Humanities & Sciences

Neuroscience

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Life Science