Mirror Neurons and Communicative Actions

Ah, what one is not willing to go through in the name of science. This figure comes from an article by Ferrari et al (2003), which investigated mirror neuron responses to mouth actions. Mirror neurons are neurons which have been found in the premotor cortex of monkeys and apes, and are believed to exist in humans as well. These neurons fire when the animal performs a specific action (e.g., making a face with portruded lips, as above), but also when the animal sees someone else perform a similar action (Rizzolatti & Craighero, 2004).

This is terribly interesting because it appears to offer an explanation for how we make sense of the actions of other people: in this view, we understand actions by “mirroring” them in our own motor system.

The study by Ferrari et al (2003) is interesting because it contradicts the previously canonical knowledge that mirror neurons only respond to object-oriented actions, i.e., miming a grasping action yields no response, nor does the object itself. Only when an object is grasped does the neuron respond (Rizzolatti & Craighero, 2004). Ferrari et al identified a group of mirror neurons in the macaque monkey’s area F5 which responded to mouth movements. The bulk of these “mouth” neurons responded to eating-related actions, but a small group responded to communicative mouth movements, such as the lip portrusion pictured above. While you could argue that eating by necessity is an object-oriented action, the communicative movements are not so easily put into this framework.

The implication for what I’m working with right now is that mirror neurons may play a role in detecting facial expressions in humans. There is considerable evidence that faces and in particular facial expressions are perceived quite differently from other stimuli. Mirror neurons may play some part in explaining these differences.

References

Ferrari, P.F., Gallese, V., Rizzolatti, G., & Fogassi, L. (2003). Mirror Neurons Responding to the Observation of Ingestive and Communicative Mouth Actions in the Monkey Ventral Premotor Cortex. European Journal of Neuroscience, 17, 1703-1714.

Rizzolatti, G., & Craighero, L. (2004). The Mirror-Neuron System. Annual Review of Neuroscience, 27, 169-192.