Comparison of the on-line effects of different motor simulation conditions on corticospinal excitability in healthy participants

C Pfenninger,T Lapole,A Remontet,S Grosprêtre

doi:10.1038/s41598-021-92591-4

C Pfenninger, T Lapole + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-92591-4

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Abstract

In healthy participants, corticospinal excitability is known to increase during motor simulations such as motor imagery (MI), action observation (AO) and mirror therapy (MT), suggesting their interest to promote plasticity in neurorehabilitation. Further comparing these methods and investigating their combination may potentially provide clues to optimize their use in patients. To this end, we compared in 18 healthy participants abductor pollicis brevis (APB) corticospinal excitability during MI, AO or MT, as well as MI combined with either AO or MT. In each condition, 15 motor-evoked potentials (MEPs) and three maximal M-wave were elicited in the right APB. Compared to the control condition, mean normalized MEP amplitude (i.e. MEP/M) increased during MI (P = .003), MT (P < .001) and MT + MI (P < .001), without any difference between the three conditions. No MEP modulation was evidenced during AO or AO + MI. Because MI provided no additional influence when combined with AO or MT, our results may suggest that, in healthy subjects, visual feedback and unilateral movement with a mirror may provide the greatest effects among all the tested motor simulations.

Highlights

In healthy participants, corticospinal excitability is known to increase during motor simulations such as motor imagery (MI), action observation (AO) and mirror therapy (MT), suggesting their interest to promote plasticity in neurorehabilitation
From the 15 motor-evoked potentials (MEPs) recorded on each condition, we performed statistical analyses on 11.7 ± 1.7 MEPs for control condition, 9.1 ± 3.8 for MI, 11.1 ± 4 for AO, 10.8 ± 3.6 for AO + MI, 8.1 ± 3.9 for MT and 6.8 ± 4.4 for MT + MI
Bonferroni post-hoc tests demonstrated a marked increase in MEP amplitude during MI (t = 3.88, P = .003, d = 0,42), MT (t = 6.75, P < 0.001, d = 0.66) and MT + MI (t = 5.52, P < 0.001, d = 0.47) compared to the control condition

Summary

Introduction

Corticospinal excitability is known to increase during motor simulations such as motor imagery (MI), action observation (AO) and mirror therapy (MT), suggesting their interest to promote plasticity in neurorehabilitation Further comparing these methods and investigating their combination may potentially provide clues to optimize their use in patients. Studies using transcranial magnetic stimulation (TMS) in healthy participants demonstrated an increase in motor-evoked potential (MEP) amplitude during MI in the first dorsal interosseous (FDI)[8,9], the abductor pollicis brevis (APB)[9,10], and the flexor carpi radialis (FCR)[11,12] muscles This suggests an increased corticospinal excitability during imagery.

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