The Mirror System in Monkeys and Humans and its Possible Motor-Based Functions

Abstract

Mirror neurons are neurons, found in both ventral premotor and inferior parietal cortex of the monkey, that respond during both observation and execution of motor acts. This property suggested that the mirror neuron system underpins the understanding of goal-related motor acts. The existence of a mirror system has also been demonstrated in humans. The research of the last 10 years has been crucial for specifying in more details the properties of mirror neurons in monkeys. For instance, it has been recently shown that the response to an observed motor act can be modulated by the space sector in which the act is performed, and that part of mirror neurons can be modulated by the perspective from which the motor act is observed. In humans, evidence accumulated in favor of an involvement of the mirror matching mechanism in several types of social functions, such as imitation, intention and emotion understanding and speech comprehension. In this article we will first describe the main properties of mirror neurons in monkeys and some of the studies demonstrating the presence of an action observation or execution matching system in humans and also discuss possible criticisms to the presence of mirror neurons in our species. Then we will be present the evidence on the role of the mirror system in intention understanding and imitation. Finally, we discuss the role of the mirror system in language evolution and, starting from the recent evidence of the presence of mirror neurons in songbirds, we suggest that the mirror matching system of primates could derive from an ancestor common to primates and birds.KeywordsMirror SystemMirror NeuronsObserved Motor ActVentral PremotorGoal-directed Motor ActsThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.