Scientists Say Neuron Provides Ability to Mimic
RENEE MONTAGNE, host:
People can learn new dance steps without moving a muscle by simply watching someone else dance. Our brains figure out how to mimic it. Scientists are beginning to think they understand where this ability comes from. They've traced it to specialized brain cells called mirror neurons. NPR's Jon Hamilton reports.
JON HAMILTON reporting:
Scientists discovered mirror neurons while studying monkeys. The researchers were looking at brain cells involved in physical movements. Dr. Vilayanur Ramachandran of the University of California, San Diego, says they noticed that one type of neuron was clearly different from the rest.
Dr. VILAYANUR RAMACHANDRAN (University of California, San Diego): The neuron would not only fire when the animal approached and grabbed a peanut but also fired when the monkey watched another monkey performing exactly the same actions.
HAMILTON: The neuron was acting as a sort of mirror of the action. Ramachandran says it soon became clear that humans have a lot of these mirror neurons. They become active when we watch a person do something simple or complicated...
(Soundbite of golf swing)
HAMILTON: ...a golf shot, something most of us watch from an easy chair, but Ramachandran says even if our bodies are motionless, our brains are really busy.
Dr. RAMACHANDRAN: We're taking the visual representation of that golf swing, which is photons hitting your retina, and that pattern is being analyzed by the visual centers in the brain, and then it must be remapped onto the approach sequence of muscle twitches to produce an identical golf swing in you.
HAMILTON: Well, maybe not identical. Ramachandran says the human species has survived in part because mirror neurons give them an extraordinary ability to imitate.
Dr. RAMACHANDRAN: This allowed one-of-a-kind inventions to be transmitted culturally simply through imitation. So a child watches a parent skinning a polar bear. Mirror neurons start firing away in its brain, and it can do the same thing, and this is quite uniquely human.
HAMILTON: Mirror neurons appear to be the reason that even infants can mimic facial expressions. Scientists say this sort of imitation helps children grasp what others are thinking and feeling. Marco Iacoboni is a scientist at UCLA who has actually measured mirror neurons as people try to read what's in another person's mind.
Mr. MARCO IACOBONI (Scientist, UCLA): You can immediately understand the emotional states of other people because what you do is basically to associate the facial expressions that those people have with the emotional feelings that you would have if you were making those facial expressions.
HAMILTON: Iacoboni has done a study that suggests mirror neurons not only help people understand an action but the intention behind that action. Imagine you see a person at a freshly set table reaching for a glass of wine. Iacoboni says you're probably assuming their intention is to drink from it.
Mr. IACOBONI: Suppose now it's the same table, dirty napkins and the food is gone and you see somebody reaching and grasping for a glass, then you associate their action with the intention to clean up the table.
HAMILTON: Iacoboni studied the brains of people as they watched lots of scenarios like these. He found that their mirror neurons were more active when they understood the intention behind an action. Some researchers believe these cells can even explain brain disorders such as autism. Ramachandran says he was intrigued by children with autism because they are less likely to imitate facial expressions or understand the feelings of people around them. So he began studying their mirror neurons.
Dr. RAMACHANDRAN: Here's a specific set of neurons with known properties such as reading people's intentions, empathy, imitation, and it's precisely that system of neurons that we showed was dysfunctional in autistic children, and it's precisely those behavioral deficits that are hallmarks of the autistic spectrum of disorders.
HAMILTON: Children with autism can improve their social skills if they are taught to look at faces and imitate others. Ramachandran says future studies may show whether that improvement is linked to better functioning of their mirror neurons.
Jon Hamilton, NPR News.
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