Tuesday, January 10, 2006

Mirror neurons and their alternative uses

When we watch a person doing something, we create an internal simulation of their actions using the same cortical structures required for the observed action. We use that simulation to predict the person's intent and emotional status. So say the "mirror neuronists".

What is the relationship to sleep and dreaming? What is the relationship to the observer effect that some say collapses quantum envelopes? What alternative uses could some brains put that network to? Since dogs are supposed to be uniquely good at anticipating human action, how much of their brains are mirror neurons?
Cells That Read Minds - New York Times
January 10, 2006

... The monkey brain contains a special class of cells, called mirror neurons, that fire when the animal sees or hears an action and when the animal carries out the same action on its own.

...The human brain has multiple mirror neuron systems that specialize in carrying out and understanding not just the actions of others but their intentions, the social meaning of their behavior and their emotions.

The discovery is shaking up numerous scientific disciplines, shifting the understanding of culture, empathy, philosophy, language, imitation, autism and psychotherapy.

Everyday experiences are also being viewed in a new light. Mirror neurons reveal how children learn, why people respond to certain types of sports, dance, music and art, why watching media violence may be harmful and why many men like pornography.

Found in several areas of the brain - including the premotor cortex, the posterior parietal lobe, the superior temporal sulcus and the insula - they [mirror neurons] fire in response to chains of actions linked to intentions.

... "When you see me perform an action - such as picking up a baseball - you automatically simulate the action in your own brain," said Dr. Marco Iacoboni, a neuroscientist at the University of California, Los Angeles, who studies mirror neurons. "Circuits in your brain, which we do not yet entirely understand, inhibit you from moving while you simulate," he said. "But you understand my action because you have in your brain a template for that action based on your own movements.

"When you see me pull my arm back, as if to throw the ball, you also have in your brain a copy of what I am doing and it helps you understand my goal. Because of mirror neurons, you can read my intentions. You know what I am going to do next."

... Language is based on mirror neurons, according to Michael Arbib, a neuroscientist at the University of Southern California. One such system, found in the front of the brain, contains overlapping circuitry for spoken language and sign language. [jf: see also sign language and the evolution of reading]

In an article published in Trends in Neuroscience in March 1998, Dr. Arbib described how complex hand gestures and the complex tongue and lip movements used in making sentences use the same machinery. Autism, some researchers believe, may involve broken mirror neurons. A study published in the Jan. 6 issue of Nature Neuroscience by Mirella Dapretto, a neuroscientist at U.C.L.A., found that while many people with autism can identify an emotional expression, like sadness, on another person's face, or imitate sad looks with their own faces, they do not feel the emotional significance of the imitated emotion. From observing other people, they do not know what it feels like to be sad, angry, disgusted or surprised.

... Nevertheless, a study in the January 2006 issue of Media Psychology found that when children watched violent television programs, mirror neurons, as well as several brain regions involved in aggression were activated, increasing the probability that the children would behave violently. [jf: another recently published functional imaging study has greatly strengthened the connection between observing violence and acting violently]

People who rank high on a scale measuring empathy have particularly active mirror neurons systems, Dr. Keysers said.

... Humiliation appears to be mapped in the brain by the same mechanisms that encode real physical pain, he said...
I'm particularly interested in alternative uses of the mirror neuron subsystem. That system is doing a lot of work at a high metabolic cost. In some humans it could be used to provide alternative functions, sacrificing social prediction. Evolution could allow this as a backup system for brain injury, or as an alternative path in relatively secure social environments. Isaac Newton, one of the great geniuses, was famously rude and unempathic. If gene defects cause widespread problems with neural connectivity (one subtype of "autism"), then could the mirror neuron network be partially repurposed? What about those persons missing a hemisphere who still manage to function well?

Update 1/10/06: Hmm. So in multiple personality disorders, do the mirror neuron subsystems take on a life of their own?

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