The imprint of action: motor cortex involvement in visual perception of handwritten letters.

Humans are able to recognize handwritten texts accurately despite the extreme variability of scripts from one writer to another. This skill has been suggested to rely on the observer's own knowledge about implicit motor rules involved in writing. To investigate the possible neural correlates of such an ability, we monitored with magnetoencephalography (MEG) the approximately 20-Hz oscillations originating from the motor cortex. The oscillations were more suppressed after visual presentation of handwritten than printed letters, indicating stronger excitation of the motor cortex to handwritten scripts. These results support the idea of embodied visual perception of handwritten scripts and the involvement of the motor cortex in the underlying action-perception link.