Mirror neurons from associative learning. a)
Before learning, sensory neurons in STS, encoding visual descriptions of observed action, are not systematically
connected to motor neurons in premotor and parietal areas involved in the
production of similar actions. b) Through social interaction and
self-observation in the course of typical development, agents receive
correlated sensorimotor experience; they see and do the same action at about
the same time (contiguity), with one event predicting the other
(contingency). This experience produces correlated activation of sensory and
motor neurons coding similar actions, and, through associative learning, c)
strengthens connections between these neurons. Due to these connections,
neurons that were once involved only in the execution of action will also
discharge during observation of a similar action; motor neurons become MNs.
Because the visual system and motor system are organised hierarchically,
some types of sensorimotor experience produce correlated activation of
sensory and motor neurons coding relatively low-level features of action
(e.g. left or right hand, power or precision grip), and thereby generate
strictly congruent, hand- and direction-sensitive MNs. Other types produce
correlated activation of neurons coding relatively high-level features (e.g.
grasping), and generate broadly congruent MNs. [Graphics by Richard Cook.
To appear in: Cook, Bird, Catmur, Press & Heyes (under review) Mirror
neurons: from origin to function.