ARE MIRROR NEURONS THE BASIS FOR COMMUNICATION?

Mirror neurons were discovered in area F5 of the ventral premotor cortex of macaque monkeys by researchers at the University of Parma, Italy, in 1992. The researchers found that these neurons had some very distinctive characteristics: they fired not only when a monkey performed a voluntary gesture (for example, turned a handle to open a door), but also when a monkey watched another monkey perform this same action.

In essence, mirror neurons react to visual stimuli that represent an interaction between a biological means of action (such as the hand or mouth) and an object. These neurons thus act as agents for recognizing purposive actions as opposed to simple movements. Even in the case of canonical neurons, which can be activated by the sight of a graspable object in the absence of movement (see sidebar), the internal representation is that of a purposive action, and not just a simple movement of the hand or arm.

This is what has led some researchers to think that mirror neurons might help to explain the cognitive foundations of language, by providing the neural substrate for the human ability to understand the meaning of other people’s actions, which is the basis for all social relations . This system of correspondences between perceptions and actions would help us to infer other people’s mental states and to interpret their actions as intentional behaviours arising from these states. We can then easily imagine how this mechanism for interpreting gestural communication might have been applied to verbal communication as well.

The hypothesis advanced is that the motor system, through its mirror neurons, is involved in perceiving speech, and that through evolution, the “motor resonance”generated by the mirror neurons has been diverted (or exapted) from its original function to serve the needs of language. One has to be impressed by the economy of such a cognitive system, in which one individual understands what other individuals are doing (or saying) on the basis of the internal representation of his or her own motor capabilities.

The point is that intentional communication between two individuals differs from the simple cries of alarm by which animals signal danger to all members of their group indiscriminately. Intentional communication, in contrast, requires one individual who is transmitting information and a second who is paying attention to receive it. Among all the possible origins of language, the first form of intentional communication among humans may have arisen from the imitation of gestures and facial expressions. Thus mirror neurons may have played a role in sharing these common representations and, eventually, a common language.