The multiform motor cortical output: Kinematic, predictive and response coding.
Observing actions performed by others entails a subliminal activation of primary motor cortex reflecting the components encoded in the observed action. One of the most debated issues concerns the role of this output: Is it a mere replica of the incoming flow of information (kinematic coding), is it oriented to anticipate the forthcoming events (predictive coding) or is it aimed at responding in a suitable fashion to the actions of others (response coding)? The aim of the present study was to disentangle the relative contribution of these three levels and unify them into an integrated view of cortical motor coding. We combined transcranial magnetic stimulation (TMS) and electromyography recordings at different timings to probe the excitability of corticospinal projections to upper and lower limb muscles of participants observing a soccer player performing: (i) a penalty kick straight in their direction and then coming to a full stop, (ii) a penalty kick straight in their direction and then continuing to run, (iii) a penalty kick to the side and then continuing to run. The results show a modulation of the observer's corticospinal excitability in different effectors at different times reflecting a multiplicity of motor coding. The internal replica of the observed action, the predictive activation, and the adaptive integration of congruent and non-congruent responses to the actions of others can coexist in a not mutually exclusive way. Such a view offers reconciliation among different (and apparently divergent) frameworks in action observation literature, and will promote a more complete and integrated understanding of recent findings on motor simulation, motor resonance and automatic imitation.
Dipartimento di Psicologia Generale, Università di Padova, Padova, Italy; Center for Cognitive Neuroscience, Università di Padova, Padova, Italy. Electronic address: luisa.sartori@unipd.it.
Luisa
L
Sartori
Dipartimento di Psicologia Generale, Università di Padova, Padova, Italy.
Sonia
S
Betti
School of Computing, University of Leeds, Leeds, UK.
Eris
E
Chinellato
Dipartimento di Psicologia Generale, Università di Padova, Padova, Italy; Center for Cognitive Neuroscience, Università di Padova, Padova, Italy; Centro Beniamino Segre, Accademia dei Lincei, Roma, Italy.
Umberto
U
Castiello
D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D007100:Imitative Behavior / Q000502:physiology*; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D010775:Photic Stimulation; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
Action observation; Motor evoked potentials; Motor resonance; Transcranial magnetic stimulation