Content area
Full text
Key Words mirror neurons, action understanding, imitation, language, motor cognition
Abstract A category of stimuli of great importance for primates, humans in particular, is that formed by actions done by other individuals. If we want to survive, we must understand the actions of others. Furthermore, without action understanding, social organization is impossible. In the case of humans, there is another faculty that depends on the observation of others' actions: imitation learning. Unlike most species, we are able to learn by imitation, and this faculty is at the basis of human culture. In this review we present data on a neurophysiological mechanism-the mirror-neuron mechanism-that appears to play a fundamental role in both action understanding and imitation. We describe first the functional properties of mirror neurons in monkeys. We review next the characteristics of the mirror-neuron system in humans. We stress, in particular, those properties specific to the human mirror-neuron system that might explain the human capacity to learn by imitation. We conclude by discussing the relationship between the mirror-neuron system and language.
INTRODUCTION
Mirror neurons are a particular class of visuomotor neurons, originally discovered in area F5 of the monkey premotor cortex, that discharge both when the monkey does a particular action and when it observes another individual (monkey or human) doing a similar action (Di Pellegrino et al. 1992, Gallese et al. 1996, Rizzolatti et al. 1996a). A lateral view of the monkey brain showing the location of area F5 is presented in Figure 1 (see color insert).
The aim of this review is to provide an updated account of the functional properties of the system formed by mirror neurons. The review is divided into four sections. In the first section we present the basic functional properties of mirror neurons in the monkey, and we discuss their functional roles in action understanding. In the second section, we present evidence that a mirror-neuron system similar to that of the monkey exists in humans. The third section shows that in humans, in addition to action understanding, the mirror-neuron system plays a fundamental role in action imitation. The last section is more speculative. We present there a theory of language evolution, and we discuss a series of data supporting the notion of a strict link between language...