Consistent evidence suggests that the way we reach and grasp an object is modulated not
only by object properties (e.g., size, shape, texture, fragility and weight), but also by the
types of intention driving the action, among which the intention to interact with another agent
(i.e., social intention). Action observation studies ascribe the neural substrate of this `intentional'
component to the putative mirror neuron (pMNS) and the mentalizing (MS) systems.
How social intentions are translated into executed actions, however, has yet to be addressed.
We conducted a kinematic and a functional Magnetic Resonance Imaging (fMRI)
study considering a reach-to-grasp movement performed towards the same object positioned
at the same location but with different intentions: passing it to another person (social
condition) or putting it on a concave base (individual condition). Kinematics showed that individual
and social intentions are characterized by different profiles, with a slower movement
at the level of both the reaching (i.e., arm movement) and the grasping (i.e., hand aperture)
components. fMRI results showed that: (i) distinct voxel pattern activity for the social and the
individual condition are present within the pMNS and the MS during action execution; (ii)
decoding accuracies of regions belonging to the pMNS and the MS are correlated, suggesting
that these two systems could interact for the generation of appropriate motor commands.
Results are discussed in terms of motor simulation and inferential processes as part of a
hierarchical generative model for action intention understanding and generation of appropriate
motor commands