The interplay between neural structures and processes underlying motor planning and proper movement initiation and guidance is still a matter of debate. The present study aimed at investigating cortical correlates of motor planning and production when execution and imagery of real-life gestures are performed, with an additional focus on potential specificities of meaningful transitive/intransitive gestures. Electrophysiological (Readiness Potential - RP) and functional near-infrared spectroscopy (fNIRS) measures were analyzed to investigate the relationship between processes supporting action planning, execution and imagination. Participants were instructed to observe videos presenting various gestures and then to execute or to imagine them. We observed comparable RP before gesture execution and imagination, with a "facilitation effect" of transitive gestures in particular for imagination. Further, while the supplementary motor regions showed similar O2Hb profiles during both execution and imagination of transitive/intransitive gestures, premotor and posterior parietal areas showed specificities respectively for execution processes and transitive gesture execution. Finally, regression analyses showed that RP amplitude is a predictive factor of subsequent hemodynamic brain activity during action production. Such predictive role was modulated by both task and gesture type factors.
Keywords: Action planning; Motor imagery; Movement execution; Readiness potential; Transitive/intransitive gestures; fNIRS.
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