I read the famous “double helix” letter by James Watson and Francis Crick in Nature when it was published in 1953—I was an undergraduate at Oxford then, reading physiology and biochemistry. I would like to say that I immediately saw its tremendous significance, but this was not the case for me or, indeed, for most people at the time.
It was only in 1962, when Francis Crick came to talk at Mount Zion Hospital in San Francisco, where I was interning, that I started to realize the vast implications of the double helix. Crick’s talk at Mount Zion was not on the configuration of DNA but on the work he had been doing with the molecular biologist Sidney Brenner to determine how the sequence of DNA bases could specify the amino acid sequence in proteins. They had just shown, after four years of intense work, that the translation involved a three-nucleotide code. This was itself a discovery no less momentous than the discovery of the double helix.
But Crick’s mind was always moving forward, and clearly he had already moved on to other things. There were, he intimated in his talk, two “other things,” great enterprises whose exploration lay in the future: understanding the origin and nature of life, and understanding the relation of brain and mind—in particular, the biological basis of consciousness. Did he have any inkling, any conscious thought, when he spoke to us in 1962, that these would be the very subjects he himself would address in the years to come, once he had “dealt with” molecular biology, or at least taken it to the stage where it could be delegated to others?
It was not until May of 1986 that I met Francis Crick, at a conference in San Diego. There was a big crowd, full of neuroscientists, but when it was time to sit down for dinner, Crick singled me out, seized me by the shoulders, sat me down next to him, and said, “Tell me stories!” I have no memory of what we ate, or anything else about the dinner, only that I told him stories about many of my patients, and that each one set off bursts of hypotheses, theories, suggestions for investigation in his mind. Writing to Crick a few days later, I said that the experience was “a little like sitting next to an intellectual nuclear reactor…. I never had a feeling of such incandescence.”
He was especially eager to hear stories of visual perception, and was fascinated when I told him of a patient who had consulted me a few weeks before, an artist who had experienced a sudden and total loss of color perception following a car accident (his loss of color vision was accompanied by an inability to visualize or to dream in color). Crick was also fascinated when I told him how a number of my migraine patients had experienced, in the few minutes of a migraine aura, a flickering of static, “frozen” images in place of their normal, continuous visual perception. He asked me whether such “cinematic vision” (as I called it) was ever a permanent condition, or one that could be elicited in a predictable way so that it could be investigated. I said I did not know.
During 1986, encouraged by the questions Crick had fired at me, I spent a good deal of time with my colorblind patient, Mr. I., and in January of 1987, I wrote to Crick. “I have now written up a longish report on my patient…. Only in the actual writing did I come to see how color might indeed be a (cerebro-mental) construct.” I had now started to wonder, I added, whether all perceptual qualities, including the perception of motion, were similarly constructed by the brain. I had spent most of my professional life wedded to notions of “naive realism,” regarding visual perceptions, for example, as mere transcriptions of retinal images—this was very much the epistemological atmosphere at the time. But now, as I worked with Mr. I., this was giving way to a very different vision of the brain-mind, a vision of it as essentially constructive or creative. (I also included a copy of my book A Leg to Stand On, because it contained accounts of personal experiences of both motion and depth blindness.)
I got a letter back a few days later—Crick was the promptest of correspondents—in which he sought more detail about the difference between my migraine patients and a remarkable motion-blind patient described by the German neuropsychologist Josef Zihl. My migraine patients experienced “stills” in rapid succession, whereas in Zihl’s patient (who had acquired motion blindness following a stroke), the stills apparently lasted much longer, perhaps several seconds each. In particular, Crick wanted to know whether, in my patients, successive stills occurred within the interval between successive eye movements, or only between such intervals. “I would very much like to discuss these topics with you,” he wrote, “including your remarks about color as a cerebro-mental construct.”
In my reply to Crick’s letter, I enlarged on the deep differences between my migraine patients and Zihl’s motion-blind woman. I mentioned too that I was working on Mr. I.’s case with several colleagues. My ophthalmologist friend Bob Wasserman had examined Mr. I. several times and discussed his case with me at length, and we had also been joined by a young neuroscientist, Ralph M. Siegel, who had just come to New York from the Salk Institute, where, as it happened, he had been close to Crick. Siegel collaborated with us, designing and conducting a variety of psychophysical experiments with our patient. I mentioned, too, that the neurophysiologist Semir Zeki had visited us from London, and had tested our patient with his color “Mondrians,” using light of different wavelengths, and with these, had confirmed that Mr. I. showed excellent wavelength discrimination. His retinal cones were still reacting to light of different wavelengths, and his primary visual cortex (an area which has been named V1) was registering this information, but it was clear that this wavelength discrimination was not in itself sufficient for the experience of color. The actual perception of color had to be constructed, and constructed by an additional process in another part of the visual cortex. Zeki felt, on the basis of animal experiments, that color was constructed in the tiny areas of the visual cortex called V4, and wondered whether Mr. I. had damage to these areas resulting from his stroke.
At the end of October 1987, I was able to send Crick the paper that Bob Wasserman and I had written, “The Case of the Colorblind Painter,”1 and having sent this article off to him, I was assailed by intense anxieties—what would he say?—but also by great eagerness to hear his reactions. Both of these feelings waxed in the weeks that followed, for Crick was out of town, his secretary told us, until mid-December.
Early in January, then, I got a response from Crick—an absolutely stunning letter, five pages of single-spaced typing, minutely argued, and bursting with ideas and suggestions. Some of them, he said, were “wild speculation,” but it was the sort of wildness that had intuited the double-helix structure of DNA thirty-five years before. “Do please excuse the length of this letter,” he added. “We might talk about it over the phone, after you’ve had time to digest it all.” Bob and I, Ralph too, were mesmerized by the letter. It seemed to get deeper and more suggestive every time we read it, and we got the sense that it would need a decade or more of work, by a dedicated team of psychophysicists, neuroscientists, brain imagers, and others, to follow up on the torrent of suggestions Crick had made.
I wrote back to Crick, saying that we would need weeks or months to digest all he had said, but would be getting to work in the meantime, doing tests of motion vision, stereo vision, and contrast vision in Mr. I., as well as more sophisticated color vision testing, and that we hoped to get high-quality MRI and PET scans to look at the activity in his visual cortex.
In his five-page letter, Crick had written, “Thank you so much for sending me your fascinating article on the color-blind artist…. Even though, as you stress in your letter, it is not strictly a scientific article, it has aroused much interest among my colleagues and my scientific and philosophical friends here. We have had a couple of group sessions on it and in addition I have had several further conversations with individuals.” He added too that he had sent a copy of the article and his letter to David Hubel, who, with Torsten Wiesel, had done pioneering work on the cortical mechanisms of visual perception.
Writing to me again in January of 1988, he said, “So glad to hear from you and to learn that you plan more work on Mr. I. All the things you mention are important, especially the scans…. There is no consensus yet among my friends about what the damage might be in such cases of cerebral achromatopsia. I have (very tentatively) suggested the V1 blobs plus some subsequent degeneration at higher levels, but this really depends on seeing little in the scans (if most of V4 is knocked out you should see something). David Hubel tells me that he favors damage to V4, though this opinion is preliminary. David van Essen tells me that he suspects some area further upstream.”
He mentioned two of Antonio Damasio’s cases: in one of these, the patient had lost color imagery, but still dreamed in color. (She later regained her color vision.) “I think the moral of all this,” he concluded, “is that only careful and extensive psychophysics on [such] a patient plus accurate localization of the damage will help us. (So far, we cannot see how to study visual imagery and dreams in a monkey.)”
I was very excited to think that Crick was opening our paper, our “case,” for discussion in this way. It gave me a deeper sense of science as a communal enterprise, of scientists as a fraternal, international community, sharing and thinking on each other’s work—and of Crick himself as a sort of hub, or center, in touch with everyone in this neuroscientific world.
Eighteen months passed without further contact between us, for I was largely occupied now with other, non-visual, conditions. But in August of 1989, I wrote to Crick again, saying that I was still working with our colorblind patient. I also enclosed a copy of my just-published book, Seeing Voices, on sign language and the culture and history of congenitally deaf people. I was especially fascinated by the way in which novel perceptual and linguistic powers could develop in congenitally deaf people, and the brain changes which both resulted from and allowed a very different perceptual experience in them, and in my book I had cited some of Crick’s thoughts in this context—he had just published a paper called “The Recent Excitement About Neural Networks.” (I also cited Gerald M. Edelman in the same context, and wondered what the relationship of these two extraordinary figures might be, since Edelman had recently relocated his Neurosciences Institute to La Jolla, practically next door to the Salk Institute, where Crick was working.)