FIGURE 4.

Modulation of brain signals by joint action. (A) Experimental setup. Participants were seated in two separate MEG systems and instructed to perform rhythmic precision-grip-like movements in synchrony with their partner, either leading or following the other’s movement. Example movement traces (red, blue) are shown at the bottom, indicating similar movement with slight delay between the participants. (B) Modulation of alpha- and beta-band power by the phase of the hand movement in the two conditions. Modulations occurred over central areas and, for beta power, also over visual cortex. Significant differences between the leader and follower conditions (right) occurred only for beta-band power recorded from visual areas. This role-specific modulation of brain activity might be reflecting the need for the follower to coordinate own proprioceptive signals with the visual feedback about the movement of the leading participant. (C) Source space projection of the results shown in panel (B). Power modulations are observed in sensorimotor cortex as well as, in the follower condition, in visual cortex. Modified from Zhou et al. (2016).