A close look at mirror neurons

Are these cells key to feelings of empathy?

Science

April 01, 2005|By Dennis O'Brien | Dennis O'Brien,SUN STAFF

If you're a golfer, your brain reacts differently from a duffer's when when you watch Tiger Woods sink a putt. Likewise, if you're a ballet dancer watching Amanda McKerrow perform a pirouette.

Researchers say the same special class of neurons fire off whenever you perform a task - or watch someone else perform it. But how often those cells fire away probably depends on whether you've actually done what you're watching.

Known as mirror neurons, these cells may play a role in how we learn to produce language, empathize with other people and read their intentions. Scientists now believe that understanding how they work could help unravel the mysteries behind autism and other conditions.

"Potentially, there are all kinds of implications," said David Glaser, a cognitive neuroscientist and senior research fellow at University College London.

Researchers have focused on mirror neurons since the mid-1990s, when Italian scientists planted electrodes in the brains of Rhesus macaques. They found that brain cells in the premotor cortex fired off electrical signals, whether the monkeys performed a task, or just watched someone perform it. The nature of the task - whether it was reaching for an apple or cracking open a peanut shell - didn't matter.

Researchers at the University of Parma in Italy labeled the cells mirror neurons in 1996 because they seem to fire in sympathy with the actions of others.

Brain scans have taught researchers that the same effect occurs in a section of the human temporal lobe known as Broca's area. But the human-brain-scan studies show that our mirror neurons may play a greater role than a monkey's, possibly helping us produce language and understand and feel the pain of other people.

"If you see images of somebody with a painful facial expression, your mirror neurons will fire off more if you're an empathetic person," said Dr. Marco Iacoboni, a physician and researcher who directs a mirror-neuron research center at UCLA.

Glaser, whose studies focus on how the brain visualizes the world, found that the mirror neurons of 10 ballet dancers fired more often when they were watching movements that they themselves could perform than when they watched other types of movements. Experts in capoeira, a form of Brazilian martial arts, had similar reactions, firing off more mirror neurons when they watched someone performing their own specialties.

Glaser said the same probably holds true for athletes in other sports, different types of dancers or those with any particular skill. Mirror neurons also may help us understand other people's emotional states - and whether the people are being deceptive, he said.

"I think we are looking at a genuine, real world phenomenon. The same thing holds for a football fan or anyone else," he said.

Experts are particularly excited about mirror neurons as a key to therapies for the autistic because of their location in the brain.

"They're in the region that allows us to detect other people's intentions," said Dr. James Harris, director of developmental neuropsychiatry and a professor of pediatrics and psychiatry at the Johns Hopkins School of Medicine. Some experts say we use the same region of the brain to understand the feelings of other people.

Those skills are largely missing in the autistic. Although any therapy based on mirror neuron research is likely years away, Harris remains interested in mirror neurons because of the role they play.

"The first step toward empathy is appreciating the other person's intentions," Harris said. "But if you have a system that doesn't function properly, how are you going to be able to understand those intentions?"

Harris said experts are divided into two camps about mirror neurons and autism. Some believe that the mirror neurons of autistic people are dysfunctional. Others argue that the neurons never fire because the autistic person doesn't pay sufficient attention to a movement or task to activate them.

"It's when you pay attention to a movement that you start to see this activation of mirror neurons. In the autistic person, it may be they're not utilizing them properly because of attentional problems," he said.

In a study published last month, a researcher at the University of Montreal showed that mirror neurons in 10 mildly autistic adults failed to fire as freqently in as they did in 10 control subjects, all of whom watched a 10-second movie clip of finger and thumb movements. The median age of the subjects was 39.

Hugo Theoret, the psychologist whose study was published in Current Biology, plans to conduct future studies of the mirror neurons in people with more severe autism, as well as schizophrenic and psychopathic patients who have difficulty understanding the feelings of others.

"There seems to be a link between how these neurons perform and a person's social functioning abilities," he said.

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