A Neuron's Obsession Hints at Biology of Thought
October 10th 2009 04:59
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Researchers have discovered that in the vast neural network of the brain, some cells are, to use a technical term, celebrity groupies.
Probing deep into human brains, a team of scientists discovered a neuron roused only by Ronald Reagan, another cell smitten by the actress Halle Berry and a third devoted solely to Mother Teresa. Testing other single human neurons, they located a brain cell that would rather watch an episode of "The Simpsons" than Madonna.
Neuroscientists at UCLA discover single human neurons respond to specific celebrities, including Oprah Winfrey. They say these brain cells show it only takes a simple circuit of neurons to encode an idea, perception or memory.
In one sense, these findings are merely noise. They arise from rare recordings of electrical activity in brain cells, collected by neuroscientists at the University of California, Los Angeles, during a decade of experiments with patients awaiting brain surgery for severe epilepsy. These tingles of electricity, however, gave the researchers the opportunity to locate neurons that help link our perceptions, memories and self-awareness.
In their most recent work this year, the research team reported that a single human neuron could recognize a personality through pictures, text or the sound of a name -- no matter how that person was presented. In tests, one brain cell reacted only to Oprah Winfrey; another just to Luke Skywalker; a third singled out Argentine soccer star Diego Maradona.
Each neuron appeared to join together pieces of sensory information into a single mental impression. The researchers believe these cells are evidence that it only takes a simple circuit of neurons to encode an idea, perception or memory.
"These neurons will fire to the person no matter how you present them," says bioengineer Rodrigo Quian Quiroga at the U.K.'s University of Leicester who studied the neurons with colleagues at UCLA and the California Institute of Technology. "All that we do, all that we think, all that we see is encoded by neurons. How do the neurons in our brain create all our perceptions of the world, all our emotions, all our thinking?"
At its simplest, a neuron is a nerve cell, one of the myriads that make up our central nervous system. Each cell can send and receive the electro-chemical signals that charge our thoughts and emotions.
On average, there are more neurons in the human brain than there are galaxies in the known universe -- about 100 billion in all, arranged on a scaffold of one trillion or so supporting, thread-like glial cells. Our inspirations race through thousands of miles of nerve fibers and axons so compacted that our entire neural network is no larger than a coconut. No two brains are alike, not even those of identical twins.
To these researchers, neurons are the Lego bricks of the brain -- a construction kit that can self-assemble into a cathedral of thought. "The idea of justice is probably generated by a small set of neurons firing," says Caltech biophysicist Christof Koch, who studies the biological basis of consciousness. "It must be true of all the things that we think about ... the number pi ...God."
In some ways, each neuron does act as if it has a mind of its own. Some fire only when they perceive a straight line; others just when they detect a right angle. New neurons form every day. No one knows how the cells can encode a complex thought or how so many neurons can make a mind.
From: The wall street journal
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