AbstractObserving the action of another person can cause the activation of motor codes, which are responsible for the execution of action. This coupling between observation and execution may be modulated by distinguishing self- and other-generated actions. That is, the affect of observation-activated motor codes may be reduced by a greater self-other distinction. Of interest, self-other distinction may be enhanced by sensorimotor experiences. In Experiment 1, the influence of sensorimotor experiences pertaining to self-generated action on involuntary movement interference (motor contagion) was examined. In pre- and post-test, participants executed horizontal arm movements while simultaneously observing a congruent (horizontal) or incongruent (vertical) movement. For training, different groups executed horizontal arm movements with or without visual feedback of their limb. Contagion effects at pre-test (greater orthogonal movement deviation for incongruent compared to congruent) were eliminated at post-test for the vision group, but remained for the no vision group. In Experiment 2, TMS was used to provide a neurophysiological indicator of contagion. In pre- and post-test, TMS was provided to M1 during the observation of index and little finger abduction. During training, participants executed index or little finger movements with or without visual feedback. Congruency effects at pre-test (greater excitability for congruent compared to incongruent) were eliminated at post-test following practice with vision, but remained following practice without vision. These findings indicate how intrapersonal sensorimotor experiences can modulate interpersonal sensorimotor couplings. This modulation likely emerged because intrapersonal sensorimotor experiences refine internal models of action, which enhance the distinction between self- and other-generated actions.
Acknowledgments: This research was supported by a number of grants awarded from the Natural Sciences and Engineering Research Council of Canada (NSERC).