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Excitatory/inhibitory motor balance reflects individual differences during joint action coordination.
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  • Enrico Vescovo,
  • Pasquale Cardellicchio,
  • Alice Tomassini,
  • Luciano Fadiga,
  • Alessandro D'Ausilio
Enrico Vescovo
Istituto Italiano di Tecnologia

Corresponding Author:[email protected]

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Pasquale Cardellicchio
Università degli Studi di Ferrara
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Alice Tomassini
Istituto Italiano di Tecnologia
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Luciano Fadiga
Istituto Italiano di Tecnologia
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Alessandro D'Ausilio
Istituto Italiano di Tecnologia
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Abstract

Joint action (JA) is a continuous process of motor co-regulation based on the integration of contextual (top-down) and kinematic (bottom-up) cues from partners. The fine equilibrium between excitation and inhibition in sensorimotor circuits is, thus, central to such a dynamic process of action selection and execution. In a bimanual task adapted to become a unimanual JA task, the participant held a bottle (JA), while a confederate had to reach and unscrew either that bottle or another stabilized by a mechanical clamp (No_JA). Prior knowledge was manipulated in each trial such that the participant knew (K) or not (no_K) the target bottle in advance. Online transcranial magnetic stimulation (TMS) was administered at action-relevant landmarks to explore corticospinal excitability (CSE) and inhibition (cortical silent period - cSP). CSE was modulated early on before the action started, if prior information was available. In contrast, cSP modulation emerged later during the reaching action, regardless of prior information. These two indexes could thus reflect the concurrent elaboration of contextual priors (top-down) and the online sampling of partner’s kinematic cues (bottom-up). Furthermore, participants selected either one of two possible behavioural strategies, preferring early or late force exertion on the bottle. One translates into a reduced risk of motor coordination failure and the other into reduced metabolic expenditure. Each strategy was characterised by a specific excitatory/inhibitory profile. In conclusion, the study of excitatory/inhibitory balance paves the way for the neurophysiological determination of individual differences in the combination of top-down and bottom-up processing during JA coordination.
03 Nov 2023Submitted to European Journal of Neuroscience
03 Nov 2023Assigned to Editor
03 Nov 2023Submission Checks Completed
04 Nov 2023Review(s) Completed, Editorial Evaluation Pending
20 Nov 2023Reviewer(s) Assigned