[Added October 2006]
This article about mirror neurons has prompted in my mind the following ideas. In Computer Programming (I am a programmer) we use the following trick when we write programs: when some complex computation produces only a small set of results, we replace the computation with a search in the table of possible outcomes.It seems that the brain has done the same thing with mirror neurons.Mirror neurons are a set of neurons (the equivalent of the search table) that fire when we look another person doing something. So we have the neuron that fires when we see another person moving the hand forward to shake it with someone else. Another
neuron will fire if a person is moving the hand striking a nail head with a hammer, etc …, These neurons are extremely important to simplify the image
processing otherwise necessary to understand other people’s intents.
This can be understood seeing this task from a computer program point of view.
You have the images of an alien built in some strange ways, doing something. You have to infer from this stream of images what a person is doing.
A very complex problem indeed. But wait a moment!For us the “alien” isn’t an alien really: he/she is someone built like us and the possible outcomes
of a move are really very few. So you see why the brain prefers to hardcode these possible outcomes of our action in a “table” of a few mirror
neurons. So ,when the brain looks at someone doing something, it has only to search and choose which is the correct mirror neuron to fire.
Something it can do so quickly that we effortlessly understand what
other people are doing .
Another trick used by the brain is that
the mirror neurons for the action “drink from a cup of coffee” are
near the neurons that fire when we drink from a cup i.e. near the place where
are the neurons that start the same action in our body.In fact they are a subset of these neurons:i.e. the mirror neurons fire both when we drink a cup or see another drinking a cup. Mirror neurons were in fact discovered by chance by
Giacomo Rizzolatti and his colleagues at the University of Parma monitoring the motor neurons of monkeys.
What is interesting in this mirror neurons system is that we have it in part hardcoded from the birth: this explains why newborn babies can imitate adults. If you stick your tongue out of the mouth in front of a newborn baby , he does the same! But the system develops and changes during all life as we learn to do new things. The hand movements of an expert piano player fire
completely different set of mirror neurons in an observer who is an expert player himself or someone who doesn’t know how to play piano!
People with autism seem to have a deficit in this system. To understand other peoples intentions they have to make a lot of effort : reason about the
images and try ,by comparing these with other images they have in memory, to decide what’s happening. Just imagine how scaring this is: this person coming toward you with raised hands is going to greet you , to hit you or what else… They have no clue. This information overload explains
why autistic people fear other people’s
eye contact. It is something similar to our ability to recognize people’s faces. Normally this is effortless
and you can assume that we must have in our brain a “table” of neurons each one connected to a well known person that fires when we see this person. But when we lose this capacity (
Prosopagnosia) then to recognize a person you must make an effort and try to use other cues . An experience that is both scaring and difficult.