The answer to any question these days seems to be mirror neurons as if magic was an acceptable explanation if the magician was a neuron. They are used to explain imitation, language, empathy and theory of mind effects. There are cells that are active if a particular motor act is performed or if it is seen to be performed by another. They have been given the name mirror neurons because presumably the mirror neurons for a particular action would be firing in both the actor and observer of the action at the same time.
We can think of them as cells that fire when the concept of a particular motor act is an appropriate concept. There is nothing magic in that. Some have taken the role of mirror neurons further and have made them the central component of a theory of mind-reading because the observer and the actor have same mirror neuron activity, the observer can understand the intention of the actor. It is true that we are fairly good at understanding the intentions of others, but I have assumed that this was essentially good guessing using a complex cognitive process.
In a paper, Pierre Jacob examines the original theory of Gallese and Goldman. Jacob characterizes their theory as two ideas. First that the mirror neurons in the agent and observer resonate because the observer replicates the mirror neuron activity of the agent. Second, the activity of mirror neurons in the observer are instrumental in deciding what intentions the agent had, the intentional cause of the action.
Jacob feels both ideas are flawed. Mirror neurons have some aspects of intention in their functioning and therefore cannot be the sole source of knowledge about intention. For example, a reach with the hand elicits different mirror neurons depending on whether there is a target around. Further a motor act can have many intentions and so cannot be the sole source of knowledge about the agent’s intention. For example, a reach with the hand can be to grasp something or just touch it.
Jacob proposes that mirror neurons along with sensory data are used to predict the agent’s future intentions and actions. This becomes a complex cognitive process rather than an almighty mind-reading leap.
MNs do not compute a representation of the agents intention from a representation of her motor command, in accordance with an internal forward model. Instead, they compute a representation of the agents motor command from a prior representation of the agents intention, in accordance with an internal inverse model. Thus, the present account does not detract from the significance of MNs for primates social cognition, since it emphasizes their contribution to an observers ability to predict a conspecifics next motor act.
JACOB, P. (2008). What Do Mirror Neurons Contribute to Human Social Cognition? Mind & Language, 23 (2), 190-223 DOI: 10.1111/j.1468-0017.2007.00337.x
Gallese, V. and Goldman, A.I. (1998). Mirror neurons and the simulation theory of mindreading Trends in Cognitive Sciences (2), 493-501