Friday, December 30, 2005

Mirror, Mirror

We're starting to get closer to some brain functions that have a lot to do with what makes us human, a subject that continues to fascinate me. (prior posts)

At the heart of so many behaviors we tend to associate with "being human" is a cluster of neurons called mirror neurons. This is a hot topic in neuroscience, because the mirror neuron system seems to underly so many advanced cognitive functions.
...mirror neurons play a major explanatory role in the understanding of a number of human features, from imitation to empathy, mindreading and language learning. It has also been claimed that damages in these cerebral structures can be responsible for mental deficits such as autism. - European Science Foundation
These same structures are found in some evolutionarily related species, but seem to be more developed in humans. Some experiments by Derek Lyons at the Yale Cognition and Development Lab start to indicate that imitation really is the sincerest form of flattery - so much so that it is hard-wired into our brains (discussed in Children Learn by Monkey See, Monkey Do. Chimps Don't- New York Times (registration required) For those who don't want to register with NYT to see the article, here is the gist.
[The experiments are] evidence that humans are hard-wired to learn by imitation, even when that is clearly not the best way to learn. If he is right, this represents a big evolutionary change from our ape ancestors. Other primates are bad at imitation. When they watch another primate doing something, they seem to focus on what its goals are and ignore its actions.
One of my heroes of neuroscience, V.S. Ramachandran, has an interesting article on the myriad of ways mirror neuron affect us. Language, cultural transmission of knowledge, empathy, autism, and many other "human" traits emerge from these special neuron clusters.

From my readings, I have formed an impression that this system is critical to our ability to transmit knowledge from one person to another, our ability to understand another person and to cooperate with them, and our very ability to internally model human behavior, including our own (which is at the core of my definition of consciousness).

The idea goes like this. Over time (and evolution) the brains of our ancestors took the basic modeling capabilities inherent in physical systems (such as the ability to tell how far out to reach a hand to reach an apple), and used some of this capacity to model other "systems". At some point, and I'm not certain which would have come first (perhaps they came together, since they use the same system), the ability to model other beings internal states was developed to a certain degree, and we also gained the ability to hold a continuous model of our own inner states. This state of self-modeling is what we call self-awareness, and is at the heart of what we mean when we say we are conscious.

Consciousness is the continual modeling of the world, our relationship to it, and the state of these models themselves. Disruptions in consciousness are disruptions to any of the myriad of subsystems necessary to peform continuous modeling - short term memory, mirror neurons, etc.

If the field of Artificial Intelligence is going to make any true progress, it will be in understanding how this modeling works to such a degree that we can model it.

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