|Prof. Michael Gazzaniga
If you walk into the office of a scientist, chances are you’ll see a white board hanging on the wall, covered with scrawls. A molecular biologist’s white board might be covered by hideous tangles of protein chains. A geophysicist might doodle India crashing into southern Asia.
The scribbles of Dr Michael Gazzaniga, director of the Center for Cognitive Neuroscience at Dartmouth, are more metaphysical. Arrows travel from a pair of eyes into a cartoon brain, finally ending at the word ‘Apple’. Another picture bluntly sums up the modern debate over free will, with a stick figure’s head labeled ‘Brain’, and two bubbles point toward it ' one labeled ‘Judge’ and the other ‘Neu’ ' short for neuroscience. Floating uncertainly off to one side is a third bubble that asks, ‘Mind'’
Big questions are Gazzaniga’s stock in trade. In the 1980s, he helped found cognitive neuroscience, a discipline designed to find out how the mind emerges from the brain. Today, at age 65, he continues to oversee a busy lab, where brain scans offer clues to how we unconsciously create theories to explain the outer world and our inner lives.
Gazzaniga deals with another set of big questions as a member of President George W. Bush’s Council on Bioethics, where he and his fellow members grapple with the moral dimensions of cutting-edge scientific research ranging from life-extending medicine to gene therapy. While he is congenial and diplomatic, Gazzaniga has also proved to be a powerful voice of dissent on the council.
These two experiences, as veteran neuroscientist and fledgling bioethicist, have come together in a new book by Gazzaniga called The Ethical Brain. In it, Gazzaniga argues that understanding the latest developments in neuroscience is essential for the public to make sound decisions about the promise and dangers of advances in medicine. Neuroscience is even shedding light on how moral beliefs take shape in our brain.
“If people learn more about what the underlying brain story is, I think it will help them think more clearly about the situation,” Gazzaniga said in an interview at his Dartmouth office.
Other neuroscientists have high praise for Gazzaniga’s book, which is one of the first examinations of neuroethics, the intersection of ethics and neuroscience.
“It’s a new lens for looking at these issues, and he’s the first person to focus it and get a sharp picture,” said Dr Judy Illes, director of the program in neuroethics at the Stanford Center for Biomedical Ethics.
Gazzaniga’s career began in the lab of Dr Roger W. Sperry, a California Institute of Technology neuroscientist who won the 1981 Nobel Prize in Medicine for his studies on the connection between the brain’s hemispheres. The right side of the brain is linked to the left side of the body, and vice versa. The two hemispheres communicate through a bundle of fibres called the corpus callosum. Sperry showed in animal experiments that if the corpus callosum was cut, each hemisphere became unaware of what was experienced in the other.
Gazzaniga studied this effect in humans. Surgeons sometimes cut the corpus callosum of people with severe epilepsy to reduce their seizures. In 1960, Gazzaniga examined one such patient, known as W.J. He found that human hemispheres became isolated as well. W.J. could put together a simple jigsaw puzzle with either his left or right hand, for example, but not both.
The hemispheres also displayed different strengths and weaknesses. W.J. could read complicated writing with his right eye, but with his left eye he gave only a blank response.
“Boom ' the whole thing unfolds in front of your eyes,” Gazzaniga said. “It was a great moment. I’m not sure I’ve had such a great moment of a scientific nature since.”
Studies on split-brain patients have dominated Gazzaniga’s work ever since. In the 1970s, he and his colleagues reported that the left hemisphere acts as an interpreter, creating theories to makes sense of a person’s experiences.
Their first clue came from an experiment Gazzaniga carried out with Dr Joseph LeDoux, now at New York University. A patient called P.S. was shown a picture and was then asked to choose a related image from a set of other pictures. What P.S. didn’t know was that he was being shown a different image in each eye.
Gazzaniga and LeDoux showed P.S. a picture of a chicken claw in his right eye and a snow-covered house in the left eye. P.S. pointed to a chicken with his right hand and a snow shovel with his left.
“I’ll never forget the day we got around to asking P.S., ‘Why did you do that'’” said Gazzaniga. “He said, ‘The chicken claw goes with the chicken.’ That’s all the left hemisphere saw. And then he looks at the shovel and said, ‘The reason you need a shovel is to clean out the chicken shed.’”
Gazzaniga hypothesised that P.S.’ left hemisphere made up a story to explain his actions, based on the limited information it received.
Gazzaniga and his colleagues have carried out the same experiment hundreds of times since, and the left hemisphere has consistently acted this way.
“The interpreter tells the story line of a person,” Gazzaniga said. “It’s collecting all the information that is in all these separate systems that are distributed through the brain.” While the story feels like an unfiltered picture of reality, it’s just a quickly thrown-together narrative.
In the late 1970s, Gazzaniga rallied his colleagues to turn this sort of research into a full-fledged field, which they called cognitive neuroscience. He helped organise a scientific society and started a journal, and every five years he edits a gigantic tome summarising what scientists know about how the mind emerges from the brain.
“More than anyone else, Mike Gazzaniga created the field of cognitive neuroscience,” said Dr George Miller, a cognitive psychologist at Princeton.
In December 2001, Gazzaniga was invited to join the bioethics council by Dr Leon Kass, its current chairman. “I said, ‘I don’t know anything about bioethics,’” Gazzaniga recalled. Kass assured him that the council wasn’t supposed to be a group of bioethicists, and Gazzaniga agreed to join.
The council immediately took up the debate on stem-cell research. Gazzaniga supports the cloning of cells to produce embryos that can be used to extract stem cells. Others on the council felt very differently. They argued that a fertilised human egg represented a potential unique individual and that creating such eggs solely for research was wrong.
Gazzaniga is quick to point out that his differences with other council members were strictly intellectual. “There’s no one I don’t respect on the committee. They’re all smart people,” he said. “I heatedly disagree with some of them, but they’re not lunatics.”
Nevertheless, he did not hesitate to dispute their argument. At one meeting in 2002, Kass described his sense of awe at watching cells divide. “I countered him with, ‘You ever see a tumor cell divide'’” Gazzaniga said. “It’s also pretty miraculous event, but all it does is fill you up with rage. You can look at it in two different ways.”
|Thought control: Cover of Gazzaniga’s book
Gazzaniga argues that it is meaningless to call a fertilised egg a potential human being. “There’s potential for 30 homes in a Home Depot, but if the Home Depot burns down, the headline isn’t ‘30 Homes Burn Down.’ It’s ‘Home Depot Burns Down,’” Gazzaniga said.
He argues that stem-cell policy-makers should take brain death as their model. After brain death, surgeons routinely remove organs for transplants. Stem-cell research should, therefore, be acceptable on embryos in which the structures that will develop into the brain have not yet emerged - before 14 days post-fertilization.
The actual biology doesn’t conform to notions of unique human potential in early embryos, Gazzaniga argued. A single fertilized egg can split into twins ' turning one supposedly unique human being into two. What’s more, twins can then sometimes fuse back together into a single embryo, known as a chimera. “So we had one person, and then we had two people, and then we have one person again. So what’s that all about'” he asked.
In The Ethical Brain, Gazzaniga discusses his views on stem-cell research, along with a range of other important issues. He describes his worry that the techniques of neuroscience may be misused.
For example, he thinks it is wrong to use neuroimaging as a lie detector or as a tool to determine whether criminals are responsible for their crimes. “It shouldn’t be dragged into the courtroom,” he said. “I think it’s totally misused if you’re trying to find the errant pixel in the brain that’s responsible for why someone killed someone.”
Neuroscience’s biggest contribution to ethics, Gazzaniga predicted, is only just emerging: a biological explanation of morality. “In the next 20 years, we’re probably going to define why our species seems to have a certain sort of moral compass,” he said.
Current research suggests that this moral compass appears to be the product of the human brain’s intricate circuitry for understanding other people’s thoughts and feelings. Just looking at pictures of people stubbing their toes in doors, for example, activates the same regions of the brain that switch on when people stub their own toes.
“When I have an empathetic moment, I literally feel your pain,” Gazzaniga said.
Gazzaniga argues that when we experience these feelings, the brain’s interpreter produces rational explanations for them. The particular explanation it produces depends on a person’s particular upbringing. “Each culture may build up a theory, and that may be passed down as traditions and religious moral systems.”
But, he said, “the basic reason you don’t kill is because your brain tells you it’s not a good idea to kill.”