Evolution of mirror systems: a simple mechanism for complex cognitive functions.

Mirror neurons (MNs) were first discovered in monkeys and subsequently in humans and birds. While MNs are deemed to play a number of high-level cognitive functions, here we propose that they serve a unitary form of sensorimotor recognition of others' behavior. We caution that this basic function should not be confounded with the higher order functions that stem from the wider cortical systems in which MNs are embedded. Depending on the species, MNs function at different levels of motor event recognition, from motor goals to fine grained movements, thus contributing to social learning and imitative phenomena. Recent studies show that MNs coding has a prospective nature, suggesting that MNs also play a role in anticipating and predicting the behavior of others during social interactions. The presence of mirroring mechanisms in subcortical structures related to visceromotor reactions and the large diffusion of imitative phenomena among animals suggest that MN systems may be more ancient and widespread than previously thought.