These neurons were discovered in a particular region (called F5) of the monkey’s brain in the mid-1990s by Giacomo Rizzolati and his research team at the University of Parma. The special property of mirror neurons is that they are activated both by the observation and the execution of a specific action. For example, mirror neurons fire both when the monkey grasps a piece of food and when it sees someone else grasp the food, something referred to as the ‘action understanding’ hypothesis, the brainchild of Vittorio Gallese. These neurons do not fire when the monkey uses the hand to perform a different action (e.g., pushing away the food). They seem to code ‘grasping the food’ whether done by self or other. They do not, however, respond to meaningless actions, but seem to be specifically attuned to actions with clear goals, an attunement that is modality specific as the actions can be perceived via any sensory modality. Since its inception, the mirror neuron hypothesis has burgeoned from accounting for the neural basis of understanding the actions of others to involvement in feelings of empathy and speech. The role of the mirror neuron system in empathy has led inevitabilty to a link with autism via the ‘broken mirror’ hypothesis, as promoted by Marco Iacobini and others such as Vilayanur S. Ramachandran [put simply: dysfunctions in mirror neurons give rise to the lack of empathy and a theory of mind in (severely) autistic individuals]. Linking mirror neurons to autism in this way, as well as to empathy and speech, has not gone without criticism. One of the most voluble critics has been Greg Hickok, as can be discerned in some of his writings. While there are such things as mirror neurons, he disputes the main role they have been accorded in autism, empathy and speech through the aegis of the action understanding hypothesis. In his view, mirror neurons enable meanings to associated with actions rather than encoding the meaning of actions. Consequently, they facilitate the process of using others’ actions in making our own choice of how to act. According to Hickok, action understanding is not a function of the motor cortex, but rather cortical areas such the superior temporal sulcus that is known to promote the ability to ability to associate objects with goals (i.e., to decide what an object or action is ‘for’). Overall, there is less ‘hype’ about the specific functions of mirror neurons, and a more questioning approach as to whether they constitute a unique class of neurons and how they might a acquire their functions. These and other issues formed an important part of the first-ever conference on mirror neurons, Mirror neurons: new frontiers, held in Erice, Sicily, from August 31 to September 6, 2012.
See Autism, Common coding, Empathizing/Empathy, Inferior parietal lobe (IPL), Motor cortex, Neuron, Superior temporal sulcus and gyrus, Theory of the child’s mind (ToM)