It has been proposed that so-called mirror neurons have an important role in the development of self-awareness. They are also important in our ability to emphathize and imitate others. Babies copy facial expressions and it is very cute when they stick out their tongue or yawn in imitation. This behavior has an important function and the babies´ brains are hardwired to perform them. Here is a video of a baby macaque monkey imitating a human. You have to watch closely. The little one has a short attention span but his mirror neurons are working fine!
What are mirror neurons?
Mirror neurons were discovered accidentally a litle over 20 years ago by a team of scientists, led by Giacomo Rizzolatti in Parma in Italy. The scientists were studying an area in the premotor cortex of the brain (area F5) concerned with the planning and execution of actions. They did this by recording the activity of single neurons in macaque monkeys while the monkeys performed certain actions, for example reaching for food. One day, while a monkey was still hooked up to the machines one of the scientists reached for something while standing in the monkey´s line of vision. Immediately a burst of activity was heard! The monkey´s motor neurons in area F5 had responded to the visual stimulus (i.e. seeing the human reach for an object) as if the monkey himself had made the movement. Thus, it appeared that the monkey´s motor neurons also had sensory properties. At least some of them because, as was later found, not all of the motor neurons have this characteristic.
The first scientific paper that Rizzolatti and his colleagues wrote about their finding was rejected by the highly regarded journal Nature for a “lack of general interest”. But things changed quickly. Shortly after the initial discovery it was reported that humans have a mirror neuron system in the frontal and the parietal lobes. Soon a very active research area opened up and the scientific litterature on mirror neuron is now quite vast. A defective mirror neuron system is for example thought to underlie some deficits in children with autism. We will, without a doubt, have more to say on mirror neurons in this blog.
Illustrations show approximately the parietal and frontal mirror neuron system in humans
Mirror neurons and self-awareness
The neuroscientist Vilayanur S. Ramachandran has suggested that mirror neurons are central to our self-awareness. Describing the original mirror neuron studies he claims the monkeys were “doing a sort of internal virtual reality simulation of the other monkeys actions in order to figure out what he was “up to“”. As such the mirror neurons make us capable of taking someone else´s viewpoint. Ramachandran takes this idea further by suggesting that self-awareness is using mirror neurons for “looking at myself as if someone else is look at me” Thus the mirror neurons “that originally evolved to help you adopt another’s point of view was turned inward to look at your own self”. Ramachandran does not claim that mirror neurons are sufficient for the development of the self. Rather, he claims they have a very important role in its development. But as Ramachandran notes, we have not solved the problem of self-awareness and its neural underpinnings just by stating that it depends on mirror neurons. The quest is just beginning.
1. Iacoboni, M. (2009). Mirroring People. New York: Picador.
2. Ramachandran, V. S. (2007). The neurology of self awareness. The Edge http://edge.org/conversation/the-neurology-of-self-awareness
3. Rizzolatti, G. and Fabbri-Destro, M. (2010). Mirror neurons: from discovery to autism. Experimental Brain Research, 200, 223-237.
Photo credits: Yale Collection of Western Americana, Beinecke Rare Book and Manuscript Library (downloaded from: http://commons.wikimedia.org/wiki/File:Photograph_of_a_baby_standing_in_front_of_a_mirror.jpg)