Rapid crossed responses in an intrinsic hand muscle during perturbed bimanual movements.

Katie Y W Khong,Demetris S Soteropoulos,Ferran Galán

doi:10.1152/jn.00282.2019

Katie Y W Khong, Demetris S Soteropoulos + Show 1 more

Open Access

https://doi.org/10.1152/jn.00282.2019

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Abstract

Mechanical perturbations in one upper limb often elicit corrective responses in both the perturbed as well as its contralateral and unperturbed counterpart. These crossed corrective responses have been shown to be sensitive to the bimanual requirements of the perturbation, but crossed responses (CRs) in hand muscles are far less well studied. Here, we investigate corrective CRs in an intrinsic hand muscle, the first dorsal interosseous (1DI), to clockwise and anticlockwise mechanical perturbations to the contralateral index finger while participants performed a bimanual finger abduction task. We found that the CRs in the unperturbed 1DI were sensitive to the direction of the perturbation of the contralateral index finger. However, the size of the CRs was not sensitive to the amplitude of the contralateral perturbation nor its context within the bimanual task. The onset latency of the CRs was too fast to be purely transcortical (<70 ms) in 12/12 participants. This confirms that during isolated bimanual finger movements, sensory feedback from one hand can influence the other, but the pathways mediating the earliest components of this interaction are likely to involve subcortical systems such as the brainstem or spinal cord, which may afford less flexibility to the task demands.NEW & NOTEWORTHY An intrinsic hand muscle shows a crossed response to a perturbation of the contralateral index finger. The crossed response is dependent on the direction of the contralateral perturbation but not on the amplitude or the bimanual requirements of the movement, suggesting a far less flexible control policy than those governing crossed responses in more proximal muscles. The crossed response is too fast to be purely mediated by transcortical pathways, suggesting subcortical contributions.

Highlights

Everyday movements engage both upper limbs, in many cases to manipulate a common object
Predictive bilateral interaction is seen when one hand is about to act on an object held by the other: in such circumstances, the hand already holding the object shows a predictive increase in grip force, and this anticipatory movement can be adjusted depending on bimanual requirements of the task (Blakemore et al 1998; Witney and Wolpert 2003)
Experiment 1A: Sensitivity of crossed responses (CRs) to Perturbations of Different Directions. This experiment aimed to examine whether mechanical perturbations of different directions to the right index finger can elicit and modulate CRs on the contralateral L1DI during a bimanual task

Summary

Introduction

Everyday movements engage both upper limbs, in many cases to manipulate a common object. To perform these daily actions, the nervous system must coordinate the activity of muscles across both upper limbs together, and this happens in both a predictive and a reactive fashion. Bilateral interactions need to adapt in a fast and reactive fashion to unpredictable perturbations, as illustrated by quotidian tasks such as keeping a tray leveled with both hands. Several studies have reliably demonstrated that the amplitude of the CRs to mechanical perturbations flexibly adapts to the bimanual requirements of the task (Diedrichsen 2007; Mutha and Sainburg 2009; Omrani et al 2013)

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