Mirror neurons are a subset of so-called motor-command neurons in macaque monkeys, which have been found to become activated both when a specific type of movement is initiated, and when the same type of movement is observed being carried out by an experimenter.
Giacomo Rizzolatti and colleagues presented their discovery of mirror neurons in a paper in 1992, which describes mirror neurons found in area v5 of the Macaque cortex using recordings of single-neurons (1). Neurons with ‘mirror’ properties have later been found in the monkey inferior parietal lobule (2). It has been suggested that mirror neurons might also be found in humans, although this has not been demonstrated in any single-neuron study. Studies using indirect methods such as functional imaging, magnetoencephalography and EEG have indicated that humans may have similar mirror-circuits to monkeys (3).
1. Di Pellegrino, G., Fadiga, L., Fogassi, L., Gallese, V., & Rizzolatti, G. (1992). “Understanding motor events: a neurophysiological study”. Experimental Brain Research, 91, 176-180. (Link to PDF file).
2. Rizzolatti, G., Fogassi, L., Gallese, V. (2001) Neurophysiological mechanisms underlying the understanding and imitation of action. Nat Rev Neurosci 2:661–670
3. Rizzolatti, G. (2005) “The mirror neuron system and its function in humans” Anatomy and Embryology, 210: 419–421.