November 1, 2019 Journal article Open Access

Modulation of corticospinal output during goal-directed actions: Evidence for a contingent coding hypothesis.

Andrea Cavallo; Andrea Cavallo; Atesh Koul; Atesh Koul; Cristina Becchio; Cristina Becchio; Marco Soriano; Marco Soriano

Abstract Seeing a person perform an action activates the observer's motor system. The present study aimed at investigating the temporal relationship between execution and observation of goal-directed actions. One possibility is that the corticospinal excitability (CSE) follows the dynamic evolution of the pattern of muscle activity in the executed action. Alternatively, CSE may anticipate the future course of the observed action, prospectively extrapolating future states. Our study was designed to test these alternative hypotheses by directly comparing the time course of muscle recruitment during the execution and observation of reach-to-grasp movements. We found that the time course of CSE during action observation followed the time course of the EMG signal during action execution. This contingent coding was observed despite the outcome of the observed motor act being predictable from the earliest phases of the movement. These findings challenge the view that CSE serves to predict the target of an observed action.