Tales from Both Sides of the Brain : A Life in Neuroscience (9780062228819) Read online

  DEDICATION

  For the split-brain patients

  Who taught the world so much

  CONTENTS

  Dedication

  Foreword from Steven Pinker

  Preface

  Part 1

  Discovering the Brain

  Chapter 1

  Diving into Science

  Chapter 2

  Discovering a Mind Divided

  Chapter 3

  Searching for the Brain’s Morse Code

  Part 2

  Hemispheres Together and Apart

  Chapter 4

  Unmasking More Modules

  Chapter 5

  Brain Imaging Confirms Split-Brain Surgeries

  Chapter 6

  Still Split

  Part 3

  Evolution and Integration

  Chapter 7

  The Right Brain Has Something to Say

  Chapter 8

  Stately Living and a Call to Service

  Part 4

  Brain Layers

  Chapter 9

  Layers and Dynamics: Seeking New Perspectives

  Epilogue

  Acknowledgments

  Appendix I

  Appendix II

  Notes

  Video Figures

  Index

  About the Author

  Also by Michael S. Gazzaniga

  Credits

  Copyright

  About the Publisher

  FOREWORD

  FROM STEVEN PINKER

  SHORTLY AFTER MY ARRIVAL AT GRADUATE SCHOOL, I had second thoughts about whether the life of science was for me. I hadn’t the slightest doubt that science was for me; my doubts were about the scientific life. As an undergraduate at McGill University I did research on auditory perception with Al Bregman, who had tied the research to deep issues in cognition and epistemology, and it was natural that I would proceed to the famed Psychophysics Laboratory at Harvard. But as I was initiated into the lab’s culture, I felt the will to live draining out of me. A large fluorescent-lit room was packed with dusty audio equipment and obsolescing minicomputers, which, I was told, had to be programmed in assembly language because software packages were for weenies. The lab was inhabited by plaid-clad, pasty-faced ectomorphs, some with wives and children they rarely saw, none with a trace of humor. Their main pastime was sneering at other psychologists’ lack of mathematical rigor, though they did have one indulgence: gathering around a black-and-white TV on Sunday night to watch M*A*S*H over pizza. The lab’s first seminar, and my introduction to the dour professors who led it, was hardly more encouraging: “Let’s review the latest work on Ä i over i,” said one, alluding to Weber’s law, the psychophysical function relating discriminable increments in a stimulus’s intensity to its absolute intensity—an issue I had thought had been settled a century before, and which had inspired William James to write that “the study of psychophysics proves that it is impossible to bore a German.”

  Thankfully, I soldiered on, because my faith in the value of a scientific life was revived a few years later. When I was a lowly postdoctoral fellow, I was drafted to replace an ailing professor at the last minute and represent the Massachusetts Institute of Technology at a private conference in Santa Barbara, California, at which the icons of psychology George Miller and Michael Gazzaniga were to announce their plans for a new field they had christened “cognitive neuroscience.” The meeting opened over red wine and antipasto on a fragrant patio with breathtaking views at the aptly named El Encanto hotel. Gazzaniga’s introductory talk was periodically interrupted by wisecracks and laughter from his collaborators, and more often with wisecracks and even heartier laughter from the speaker himself. The discussion over the next day ranged from Gazzaniga’s mind-boggling discoveries about the two minds housed in a split brain to speculations about how the new science would illuminate classic problems in philosophy. At the end of the day we repaired to a beautiful house Gazzaniga had built with his own hands overlooking the Pacific, accompanied by even more food, wine, and laughter, and, if memory serves, his azalea-garlanded little daughter and her friends dancing joyously in a circle. When I visualize that day I also see bluebirds and a rainbow, but I suspect they were Photoshopped into my memory by the overall impression of warmth, vivacity, and the free-ranging interests of our bighearted host.

  Mike Gazzaniga is known for his monumental discoveries and for midwifing the field of cognitive neuroscience, but he is also known for showing that science is compatible with all the other good things in life. Science has its drudgery, of course, and its catfights big and small, but Mike has shown that it can be pursued with humor, friendship, sensual pleasure, and childlike curiosity. His thematic conferences, held in locales like Lisbon, Venice, and Napa and featuring two-hour presentations followed by four-hour conversations over food and wine, are a coveted alternative to the usual parade of ten-minute PowerPoints or the warehouse of posters and their salesmen. Nor do you have to have gray hair to be a beneficiary of Mike’s vision of enjoyable science. Mike’s Summer Institutes in Cognitive Neuroscience, known by the attendees as Brain Camp, have introduced generations of students to the field while exposing their elders to new ideas.

  The delightful memoir you are holding recounts the history of cognitive neuroscience through the eyes of one of its founders and most distinguished practitioners. Those who know Mike will hear his voice in every sentence. Those who don’t will learn about the ideas, discoveries, characters, and political implications—both academic and national—of this exciting frontier of knowledge. Both kinds of reader will be amazed by the demonstrations, ingeniously shown in real-time videos, of the key discoveries—and isn’t it just like Mike to defy the stereotype of technology-averse oldsters and try out a new medium of publication for the twenty-first century.

  In meeting the colorful people who came and went in Mike’s life, one has to wonder how one man could be so consistently surrounded by so many people he describes as so brilliant, kind, and funny. I will leave it to the reader to decide whether Mike attracts such people, describes his colleagues generously, or brings out the best in them.

  Since that glorious day in Santa Barbara, Mike has certainly brought out the best in me, teaching me, challenging me, counseling me, entertaining me, and perhaps most important, showing me that you can be a scientist and a mensch, too. And so it was a privilege when the American Psychological Association asked me to write the citation for his Award for Distinguished Scientific Contributions in 2008:

  For ingenious studies of split-brain patients which illuminated the functions of the cerebral hemispheres. His discovery that the right hemisphere can act without the awareness of the left, which then confabulates a story about what the whole person did, is a classic of psychology, rich with implications for consciousness, free will, and the self. He created the field of cognitive neuroscience, and his accessible writings inserted it into the national conversation. His wit and joie de vivre showed generations of students and colleagues the human face of science.

  PREFACE

  MORE THAN FIFTY YEARS AGO, I found myself in the middle of one of the most stunning observations in all of neuroscience: the fact that disconnecting the left and right brain hemispheres produced two separate minds—all in one head. Even I, a young neophyte, understood that these unique patients were going to change the field of brain research. As it turned out, they also changed my own life to the point that I have remained a student of their secrets from that time onward. In contemplating the way to tell the story of split-brai
n research and how it has evolved, I have come to realize the great extent to which my own march through life has been influenced by others and how, in fact, we scientists are all a composite of both scientific and nonscientific experience. Untangling these experiences and saying which caused what is impossible. It is much better to tell the story the way it actually happened.

  Most attempts at capturing the history of a scientific saga describe the seemingly ordered and logical way an idea developed. The writers of science usually do not attempt to infuse that storyline with the other realities of day-to-day living, such as the ongoing personalities of those surrounding the narrator’s life. After all, scientific knowledge is what is objectively important, not scientists. While I am completely sympathetic with this view, I now realize that that approach rarely reveals what it is like to do science or to be a scientist. The raw data of measurement is one thing. Its interpretation, on the other hand, introduces the scientist and all the influences and biases working on the scientist’s mind. Looking back over the evolution of my ideas, it is apparent how dramatically I’ve been influenced by other people. So, the actual experience in science can be quite different from the idealized view. A lot of zigzagging occurs in between the scientific experiments, as life is being lived. Science results from a profoundly social process.

  The common portrayal—that science emerges from a solitary isolated genius, always laboring alone, not owing anything to anyone—is simply wrong. It is also wrong to give the budding scientist, or those who fund research, or the general public a false impression of how science happens. In this account I want to present a different picture: science carried out in friendship, where discoveries are deeply embedded in the social relations of people from all walks of life. It is a wonderful way of life, spending one’s years with smart people, puzzling over the mysteries and surprises of nature. My life has been sprinkled with incredible characters, some famous; many great scientists; and some captivating split-brain patients. They all played a part in the evolution of my understanding of the overriding question: How on earth does the brain enable mind?

  PART 1

  DISCOVERING THE BRAIN

  CHAPTER 1

  DIVING INTO SCIENCE

  Physics is like sex: sure, it may give some practical results, but that’s not why we do it.

  —RICHARD P. FEYNMAN

  IN 1960, MOST COLLEGES WERE NOT CO-ED. I was at Dartmouth College, way out in the boonies of Hanover, New Hampshire, with hundreds of men. By the time summer came along, I had one thing on my mind. I applied for an internship at the California Institute of Technology because I wanted to spend the summer near a Wellesley girl I had met that winter. A glorious summer at Caltech, a fabled place for biology and discovery, ensued. She went on to other things. I got hooked on science. I often wonder, was I really there because of an insatiable interest in science? Or was it my interest in a girl who lived nearby? Who knows how it really works in the mercurial mind of the young? Ideas do occasionally worm their way into the interstitial areas of the hormone-addled mind.

  For me, one of those thoughts was “But how does the brain make it all work?” I had also been drawn to Caltech by reading an article in Scientific American on the growth of nerve circuits, written by Roger Sperry.1 The article outlined studies on how a neuron grew from point A to point B in order to make a specific connection. A lot, indeed I would say most of neurobiology, hangs on that simple question. Sperry was the king and I wanted to learn more about that. Besides, as I said, my girlfriend lived down the street, in San Marino.

  It wasn’t until years later when I was told about a remark made by Luis Alvarez, the great physicist from the University of California, Berkeley, that I realized that the impulse behind my question was not the same as simple curiosity. Alvarez remarked that scientists do their thing not because they are curious but because they instinctively feel something doesn’t work the way they are told it does.2 Their experimental minds kick into gear and think of another way that whatever is being discussed might work. While they can marvel at a finding or an invention, they instinctively, automatically, start thinking of alternative methods or explanations.

  In my own case, I am always thinking about different ways of viewing a problem. In part, this is because of my impoverished quantitative skills. I don’t find math easy and usually shy away from highly technical discussions of almost everything. I have discovered that, in many cases, it is easy to look at a seemingly complex problem using everyday language. This is true because of the way the world is. After all, one doesn’t need to understand the atomic composition and quantum mechanics of the billiard ball’s atoms to play a game of pool. Simple, reliable classical physics is good enough.

  We humans are all constantly abstracting, that is, taking a concrete reality and from it developing a larger theory and understanding. Thus we are continually coming up with a new, simpler layer of description that is easier for a limited brain capacity to manage. For example, take my truck. “Truck” is a new layer of description for the vehicle with open space to haul stuff and which is made up of a six-cylinder engine, radiator and cooling systems, chassis, and so forth. Now that I have a new description, every time I think about or refer to my truck, I don’t have to refer to all the parts and assemble them in my mind. I don’t have to think of them at all (until something goes wrong with one of them). We can’t deal with all the underlying complexities present in understanding the mechanisms of things every time we refer to them. It’s too much for our mental processes to handle. So we chunk it—give the mechanism a name, “truck,” thereby reducing its load on us from thousands or millions of items to one. Once we have an abstracted view of a previously highly detailed topic, then new ways of thinking about the topic—about how something works—become exhilaratingly clear. With the new key word and referent in hand, it is as if our minds are freed up to think again with new energy. Layers seems to be everywhere in Mother Nature.

  What I will call the “layered” view of the world, which I will get back to later in the book, is an idea that comes out of the science of trying to understand complex systems such as cells, computer networks, bacteria, and brains. The concept of layering can be applied to almost any complex system, even our social world, which is to say our personal lives. One layer functions nicely, driving us with its particular reward systems. Then, suddenly, we can be bumped into another layer where different rules might apply. Caltech was going to be a new layer for me. Everything I saw and did was a “first,” and there were many.

  At any rate, there I was, the summer between my junior and senior years at Dartmouth, nervously walking into Caltech for my first in this long series of firsts: meeting Roger Sperry in his Kerckhoff Hall office. He turned out to be a soft-spoken, sober guy who wasn’t rattled by much. I later heard that a few weeks before I met him, a monkey had gotten loose from the animal room and hopped into his office and up onto his desk. He looked up and said to his guest, “Maybe we should go next door. It might be quieter over there.”

  Caltech has its own heady ambience. Everyone was really smart.3 Behind office doors were superior scientists of every type plying their trades. All universities claim that sort of thing (especially today, on their hyped-up Web pages), always extolling how truly “interdisciplinary” they are. The reality is usually quite different. But at Caltech, it was (and still is) the real deal: The engines are constantly running and then running into each other. The ethos of the place is captured by the old line, “I know he invented fire, but what has he done lately?” Working in a group that pushes you to think in unfamiliar ways is a rush. It is also challenging to keep up with the pace, to say the least. This was true for all of Caltech, and it was especially true of Roger Sperry’s lab (Figure 1).

  FIGURE 1. The Sperry labs were on the third floor of Caltech’s Alles Laboratory, close to Linus Pauling’s office in the Church Chemistry Building. Across the way, in Kerchoff Hall, was A. H. Sturdevant, the father of drosophila genetics, and Ed Lewis, his Nob
el Prize–winning student.

  (Courtesy of the Archives, California Institute of Technology)

  As a newcomer, I couldn’t get enough of it. In retrospect, probably no one knows which parts of one’s storyline account for the course one takes or explain how things turn out in one’s life. Surely there are both incidental and substantive things that result in us finding ourselves in new situations and circumstances. Just as mystifyingly, in those new places, we almost instantly become part of another dynamic and another knowledge base. Quickly enough, we strive to achieve new goals.

  It soon became evident that another interest suffusing the lab, along with nerve growth circuits—the idea that hooked me into being there—was split-brain research, which was trying to find out if each hemisphere of the brain could learn independently from the other. The place was abuzz with postdocs examining monkey and cat behavior following split-brain surgery—surgery that disconnected the two half brains from each other. Where could I jump in?

  I soon came up with the idea of making a “temporary split brain.” My idea was to study rats and to use a procedure dubbed “spreading depression.” In this procedure, a small piece of gauze or gelfoam would be soaked in potassium and placed over one hemisphere of the brain to induce sleep or inactivity, leaving the other awake and able to learn.4 One of the world’s authorities on the phenomenon of spreading depression, Anthonie van Harreveld, had an office next to Sperry, so consults were going to be easy. He was a kind and gentle soul and very approachable, especially when it came to science. Unfortunately, that experiment never went anywhere in my hands, probably because the rats gave me the creeps!

  So, I turned to rabbits. Again, the idea was easy enough. Why not inject an anesthetic into the left or right internal carotid artery, which separately supplied the blood to the left or right hemisphere respectively. That would allow me to induce sleep in one hemisphere of the brain at a time, and leave the other half brain awake and able to learn. Would it work that way? At that time in science, and especially at Caltech, the only thing standing in the way of an idea or test was one’s energy and ability. No IRB (Institutional Review Board), no lack of funds, no discouraging cant from others, no endless regulations. You could just do it.