Mind, Body, World- Foundations of Cognitive Science, 2013a

the human brain (Gallese et al., 1996; Iacoboni, 2008; Rizzolatti & Craighero, 2004;
Rizzolatti, Fogassi, & Gallese, 2006) are specialized for both the generation and
interpretation of gestures and actions.
Mirror neurons were serendipitously discovered in experiments in which motor
neurons in region F5 were recorded when monkeys performed various reaching
actions (Di Pellegrino et al., 1992). By accident, it was discovered that many of the
neurons that were active when a monkey performed an action also responded when
similar actions were observed being performed by another:
After the initial recording experiments, we incidentally observed that some experimenter’s
actions, such as picking up the food or placing it inside the testing box,
activated a relatively large proportion of F5 neurons in the absence of any overt
movement of the monkey. (Di Pellegrino et al., 1992, p. 176)
The chance discovery of mirror neurons has led to an explosion of research into
their behaviour (Iacoboni, 2008). It has been discovered that when the neurons fire,
they do so for the entire duration of the observed action, not just at its onset. They
are grasp specific: some respond to actions involving precision grips, while others
respond to actions involving larger objects. Some are broadly tuned, in the sense
that they will be triggered when a variety of actions are observed, while others are
narrowly tuned to specific actions. All seem to be tuned to object-oriented action:
a mirror neuron will respond to a particular action on an object, but it will fail to
respond to the identical action if no object is present.
While most of the results described above were obtained from studies of the
monkey brain, there is a steadily growing literature indicating that the human brain
also has a mirror system (Buccino et al., 2001; Iacoboni, 2008).
Mirror neurons are not solely concerned with hand and arm movements. For
instance, some monkey mirror neurons respond to mouth movements, such as lip
smacking (Ferrari et al., 2003). Similarly, the human brain has a mirror system
for the act of touching (Keysers et al., 2004). Likewise, another part of the human
brain, the insula, may be a mirror system for emotion (Wicker et al., 2003). For
example, it generates activity when a subject experiences disgust, and also when a
subject observes the facial expressions of someone else having a similar experience.
Two decades after its discovery, extensive research on the mirror neuron
system has led some researchers to claim that it provides the neural substrate
for social cognition and imitative learning (Gallese & Goldman, 1998; Gallese,
Keysers, & Rizzolatti, 2004; Iacoboni, 2008), and that disruptions of this system may
be responsible for autism (Williams et al., 2001). The growing understanding of the
mirror system and advances in knowledge about the neuroscience of face perception
have heralded a new interdisciplinary research program, called social cognitive
neuroscience (Blakemore, Winston, & Frith, 2004; Lieberman, 2007; Ochsner &
Lieberman, 2001).
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