Anatomical and temporal architecture of theory of mind: a MEG insight into the early stages.

Representation of others' actions and mental states leads to the activation of several brain networks: the mentalizing and the "mirror neuron" systems as well as a "low level" social perception component. However, respective activations of the regions belonging to these networks remain unknown with respect to chronometrical data when static drawing stimuli are presented. To determine anatomical and temporal characteristics of theory of mind processes, magnetic signals were measured in 21 subjects during a validated nonverbal attribution of intentions task. Minimum norm estimation provides chronometric and localization data showing that regions known to be involved in the mentalizing, "mirror neuron" and social perception networks have simultaneous activations between 100 and 700 ms post-stimulus, a period which may be thought as corresponding to early stages of social processes. Among some regions, different profiles as well as modulations regarding experimental conditions suggest functional distinctions between these structures, pleading for a cooperative nature of these networks. While the left temporo-parietal area and superior temporal sulcus seem more specialized in social cues coding, we demonstrate that their right homologues, as well as the right inferior parietal cortex, are preferentially recruited during attribution of intentions stimuli compared to scenarios based on physical causality from 200 to 600 ms.