Do we really need vision? How blind people “see” the actions of others

Observing and learning actions and behaviors from others, a mechanism crucial for survival and social interaction, engages the mirror
neuron system. To determine whether vision is a necessary prerequisite for the human mirror system to develop and function, we used
functional magnetic resonance imaging to compare brain activity in congenitally blind individuals during the auditory presentation of
hand-executed actions or environmental sounds, and the motor pantomime of manipulation tasks, with that in sighted volunteers, who
additionally performed a visual action recognition task. Congenitally blind individuals activated a premotor–temporoparietal cortical
network in response to aurally presented actions that overlapped both with mirror system areas found in sighted subjects in response to
visually and aurally presented stimuli, and with the brain response elicited by motor pantomime of the same actions. Furthermore, the
mirror system cortex showed a significantly greater response to motor familiar than to unfamiliar action sounds in both sighted and blind
individuals. Thus, the mirror system in humans can develop in the absence of sight. The results in blind individuals demonstrate that the
sound of an action engages the mirror system for action schemas that have not been learned through the visual modality and that this
activity is not mediated by visual imagery. These findings indicate that the mirror system is based on supramodal sensory representations
of actions and, furthermore, that these abstract representations allow individuals with no visual experience to interact effectively with
others.