Rhesus Macaque Monkeys:
Mirror neurons are neurons which fire both when an animal acts and also when the animal observes the same action undertaken by another animal. These neurons thus mirror the action of another animal as if the observer had performed the action itself. This article from Science (17 April 2009, pp 403-6) sheds further light on the actions of mirror neurons (abstract here).
Mirror Neurons Differentially Encode the Peripersonal and Extrapersonal Space of Monkeys[Photo by Fowler&fowler cropped]
Vittorio Caggiano, Leonardo Fogassi, Giacomo Rizzolatti, Peter Thier, Antonino Casile1
Science 17 April 2009: Vol. 324. no. 5925, pp. 403 - 406
Actions performed by others may have different relevance for the observer, and thus lead to different behavioral responses, depending on the regions of space in which they are executed. We found that in rhesus monkeys, the premotor cortex neurons activated by both the execution and the observation of motor acts (mirror neurons) are differentially modulated by the location in space of the observed motor acts relative to the monkey, with about half of them preferring either the monkey's peripersonal or extrapersonal space. A portion of these spatially selective mirror neurons encode space according to a metric representation, whereas other neurons encode space in operational terms, changing their properties according to the possibility that the monkey will interact with the object. These results suggest that a set of mirror neurons encodes the observed motor acts not only for action understanding, but also to analyze such acts in terms of features that are relevant to generating appropriate behaviors.