By Hillel Aron
By Joseph Tsidulko
By Patrick Range McDonald
By David Futch
By Hillel Aron
By Dennis Romero
By Jill Stewart
By Dennis Romero
The emergence of consciousness as a respectable scientific topic is in large part due to the influence of Crick and fellow Nobel Laureate Gerald Edelman. In 1979, in an editorial accompanying a special Scientific American issue on the brain, Crick suggested that the time had come to move forward on this hitherto verboten subject. Fifteen years later, in his controversial book The Astonishing Hypothesis, Crick threw down the gauntlet: “A person’s mental activities are entirely due to the behavior of nerve cells, glial cells, and the atoms, ions and molecules that make them up.” What exactly are those behaviors? Crick advocated focusing on the subproblem of visual consciousness, and he put forward a research program designed to pinpoint the “awareness neurons” that enable us to see. His ideas have formed the inspiration for Koch’s own program, and the two scientists have been working closely together ever since.
On a muggy day this summer, I visit Koch and his mentor at Crick’s rambling ranch-style home in La Jolla. Though Crick has lived 30 years in California, where he is based at the Salk Institute, he remains an Englishman through and through. Tall and majestic, he radiates an aura of noblesse oblige, though, uncommonly for a scientist of his iconic stature, there is nothing snobbish about him. At 84, Crick still seems to be sucking in the world with the wonder of a precocious child. Now suffering from advanced cancer, he walks with a stick, but during three hours of conversation he blazes forth with ideas and fiercely held opinions. One gets the feeling that if the inexorable hand of the biological clock were not ticking so loudly, he could live yet another life with just as spectacular results.
Crick has never been one to dream small. Sitting in his study overlooking a lush, rose-filled garden and surrounded by the latest issues of a dozen research journals, he talks about the goals he set himself as a young man in the 1940s. There were two problems that interested him, he says: “the borderline between the living and the nonliving,” and the nature of consciousness. Amazingly, it took just four years — from 1949 to 1953 — for him and James Watson to elucidate the structure of DNA, thereby solving the mystery by which living things encode their own blueprint. Fifty years later, Crick still seems awestruck by this discovery. “That was a fluke,” he tells me. “I thought this problem would take me the rest of my life.” No one then imagined that the structure of the DNA molecule would turn out to be so critical to genetics: “It could have been a very boring structure.”
Instead, when he and Watson first divined the double helix, they immediately recognized that, in this twinned spiral, nature had found a miraculous means to store and implement its genetic code. Since each helix carries a complete copy of this code, the double spiral could be unzipped — thus one side could be replicated and restored, while the other side is put into action synthesizing proteins. Watson and Crick’s astonishing revelation about DNA was that the form of the molecular chain encompassed not only its code but also its function.
Having found the material structure underlying life (and since then made a slew of further discoveries in molecular biochemistry), Crick began to think about his other great interest. Might it be possible to find the material structures underlying the mind? “When I came to the Salk Institute,” he says, “I told them that I wanted to work on the brain.”
Crick began by studying the visual system of primates, a fairly conventional area of research at the time. Yet although scientists were trying to understand the process of visual awareness, the monkeys they tested were always unconscious. Crick became disenchanted. If understanding consciousness was the goal, surely that state should be the minimal requirement for test subjects. In 1980, when he received a million-dollar grant to set up a visiting-scholars program at the Salk Institute, he began to invite in other researchers to strategize about new approaches to the science of mind. One of his first invitations went to Christof Koch.
4. NEURAL LEARNING
Many contemporary philosophers of the mind assume that consciousness must be a phenomenon involving the entire brain, or at least large parts of it. Crick and Koch believe, however, that awareness is a local phenomenon emerging from the behavior of small networks or “coalitions” of neurons interacting. Because only a tiny number of neurons may be involved at any point in time, Koch notes, the physiological signature of consciousness might be quite difficult to find. Crick and Koch’s biggest challenge is to design experiments with enough rigor to tease out the conscious from the unconscious levels of perception.
At Koch’s Caltech lab, I am invited to sit in on a test session in which a student volunteer lends his mind to research by allowing his body to be zapped with electric shocks. In charge of the experiment is R. Mckell Carter, an intense young doctoral student who speaks even faster than Koch. Like his mentor, Carter is a rock climber, and he moves with the easy grace of someone who feels comfortable in his skin. Carter’s research revolves around classical Pavlovian conditioning, in which subjects learn to associate two sensory phenomena — say, the sound of a bell with the smell of food. These days, one of the stimuli is often a mild electric shock. In the experiment I am to observe, the subject is asked to look at a computer screen on which images of animals flash. Some of the images are preceded by a shock, and the question is to what extent the subject can learn to anticipate when the shock will occur. It’s the unconscious mind that registers first, by triggering a sharp rise in skin conductance on the palms. (When we are stressed, our palms sweat and the skin becomes more conductive.)