NEW YORK — As you read this sentence, the millions of neurons in your brain are frantically whispering to each other, resulting in the experience of conscious awareness.
The nature of consciousness has intrigued philosophers and scientists for thousands of years. But can modern neuroscience ever hope to crack this mysterious phenomenon? At the World Science Festival, an annual celebration and exploration of science held here in New York, a panel of experts debated what scientists can and can't learn about the mind by studying the brain.
Philosophy of the mind
Plenty of great minds have pondered the meaning of consciousness over the ages, said philosopher Colin McGinn of the University of Miami. The 17th-century French mathematician and philosopher René Descartes famously introduced the notion of mind-body dualism, which holds that the world of the body is fundamentally separate from the world of the mind, or soul, although the two may interact. In the 19th century, the English biologist Thomas Huxley helped develop the theory of epiphenomenalism, the idea that physical events in the brain give rise to mental phenomena. On the panel, McGinn also talked about panpsychism, the view that the universe is made of minds. [Watch a replay of the program here]
McGinn himself believes that no matter how much scientists study the brain, the mind is fundamentally incapable of comprehending itself. "We're rather like Neanderthals trying to understand astronomy or Shakespeare," McGinn said. Human brains suffer from a "cognitive gap" in understanding their own consciousness, he said.
Panelist Christof Koch, a neuroscientist and chief scientific officer at the Allen Institute for Brain Science in Seattle, took issue with McGinn's view. "I think it's a defeatist argument," Koch said. His rebuttal was as colorful as his outfit — a flamboyant Hawaiian shirt and orange pants. "Historically, philosophers have a disastrous record of explaining things," Koch said. Philosophers are very good at asking questions, he said, but not so good at finding satisfactory answers.
Searching for answers
Koch and the other members of the panel turn to scientific experiments to find answers. For example, the so-called mirror test, developed by psychologist Gordon Gallup in 1970, is a test of self-awareness in babies and animals. A colored dot is placed on the face of a baby or an animal subject positioned in front of a mirror. If the subject recognizes that the dot in the mirror is the same as the one on its own body, it is said to be self-aware. Babies show self-awareness after about 8 months of age. Animals such as chimpanzees, dolphins and even octopi show it, too. [That's Incredible! 9 Brainy Baby Abilities]
Koch's own work focuses on how the activity of the brain's neurons gives rise to conscious experience. In one well-known experiment, Koch and colleagues discovered that individual neurons can encode abstract concepts, such as a family member or celebrity. They even found so-called Jennifer Aniston neurons that were active only when a person saw an image of the actress. The conscious experience is of course much more complex than the activity of single neurons, but scientists can learn a lot from the ways in which these brain cells behave and are connected, Koch explained.
Panelist Nicholas Schiff, a neurologist at Weill Cornell Medical College in New York, talked about his work with people recovering from a coma, at the border between consciousness and unconsciousness. "Consciousness is a very graded phenomena," Schiff said. When a person wakes up, for example, he or she is not fully conscious, but gains awareness gradually.
Schiff went on to describe the remarkable case of a man named Donald Herbert, a firefighter who suffered a traumatic brain injury when the roof of a burning house collapsed on him, depriving him of oxygen for several minutes. The accident left Herbert blind and in a minimally conscious state for nine years. One day, his doctor gave him drugs used to treat Parkinson's disease and other brain disorders, and Herbert woke up. He retained his memory and immediately started speaking to his friends and family.
The panelists contrasted Herbert's condition to that of Terri Schiavo, a woman who was in a "persistent vegetative state" from 1990 to 2005 and became the center of a legal battle over the decision to withdraw life support. Schiavo's case was completely different from Herbert's, Schiff said, because Schiavo's brain had been extensively monitored and no signs of brain activity were found in areas associated with consciousness.
Weighing in on the discussion, panelist Mélanie Boly, a neurologist at the Belgian National Fund for Scientific Research and at the University of Wisconsin-Madison, described her work with coma patients. Boly's research aims to chart the brain activity of coma patients on the path to death or recovery. Boly also talked about a realm of consciousness all people are familiar with — sleep. By magnetically stimulating parts of the brain while people are sleeping, Boly has shown that brain activity is much more localized and less complex during sleep than during waking.
The panelists all agreed that the brain gives rise to conscious phenomena. As Koch wittily put it, "No brain, never mind!" But in contrast to McGinn's view that the mind is inherently unknowable, the others believe the subject is increasingly accessible to scientific study. Whereas McGinn admitted he finds the conundrum of consciousness frustrating, the others find it uplifting.
"I think it's so inspiring to be in [this] great time where so many things are happening, so much knowledge is gained, and later on, we hope to be able to address such deep questions for human life," Boly said.
Editor's Note: This article was updated on June 3, 2013, to correct a typo in when Terri Schiavo entered a persistent vegitative state (1990, not 1900, as previously stated).