Indirect Vibration of the Upper Limbs Alters Transmission Along Spinal but Not Corticospinal Pathways

Trevor S. Barss; David F. Collins; Dylan Miller; Amit N. Pujari

doi:10.3389/fnhum.2021.617669

Indirect Vibration of the Upper Limbs Alters Transmission Along Spinal but Not Corticospinal Pathways

Trevor S. Barss, David F. Collins, Dylan Miller, Amit N. Pujari^*

^*Corresponding author for this work

Engineering

University of Alberta

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

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Abstract

The use of upper limb vibration (ULV) during exercise and rehabilitation continues to gain popularity as a modality to improve function and performance. Currently, a lack of knowledge of the pathways being altered during ULV limits its effective implementation. Therefore, the aim of this study was to investigate whether indirect ULV modulates transmission along spinal and corticospinal pathways that control the human forearm. All measures were assessed under CONTROL (no vibration) and ULV (30 Hz; 0.4 mm displacement) conditions while participants maintained a small contraction of the right flexor carpi radialis (FCR) muscle. To assess spinal pathways, Hoffmann reflexes (H-reflexes) elicited by stimulation of the median nerve were recorded from FCR with motor response (M-wave) amplitudes matched between conditions. An H-reflex conditioning paradigm was also used to assess changes in presynaptic inhibition by stimulating the superficial radial (SR) nerve (5 pulses at 300Hz) 37 ms prior to median nerve stimulation. Cutaneous reflexes in FCR elicited by stimulation of the SR nerve at the wrist were also recorded. To assess corticospinal pathways, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation of the contralateral motor cortex were recorded from the right FCR and biceps brachii (BB). ULV significantly reduced H-reflex amplitude by 15.7% for both conditioned and unconditioned reflexes (24.0 ± 15.7 vs. 18.4 ± 11.2% Mmax; p <0.05). Middle latency cutaneous reflexes were also significantly reduced by 20.0% from CONTROL (−1.50 ± 2.1% Mmax) to ULV (−1.73 ± 2.2% Mmax; p <0.05). There was no significant effect of ULV on MEP amplitude (p > 0.05). Therefore, ULV inhibits cutaneous and H-reflex transmission without influencing corticospinal excitability of the forearm flexors suggesting increased presynaptic inhibition of afferent transmission as a likely mechanism. A general increase in inhibition of spinal pathways with ULV may have important implications for improving rehabilitation for individuals with spasticity (SCI, stroke, MS, etc.).

Original language	English
Article number	617669
Number of pages	11
Journal	Frontiers in Human Neuroscience
Volume	15
DOIs	https://doi.org/10.3389/fnhum.2021.617669
Publication status	Published - 17 May 2021

Bibliographical note

Funding
Support for this research was provided by the Churchill Travelling Fellowship through Winston Churchill Memorial Trust (to AP) and a Campus Alberta Neuroscience Postdoctoral Fellowship (TB). The vibration stimulation device used in this work was supported by funding from the Scottish Funding Council, United Kingdom (SFC) (to AP).

Acknowledgments
The authors wish to acknowledge the participants for their contributions during data acquisition.

Keywords

Human Neuroscience
indirect vibration
H-reflex
cutaneous reflex
motor evoked potential
electromyography
transcranial magnetic stimulation
sensorimotor integration
upper limb vibration
Transcranial magnetic stimulation
Upper Limb Vibration
Motor Evoked Potential
Cutaneous Reflex
Sensorimotor Integration
Indirect Vibration
Electromyography

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Cite this

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title = "Indirect Vibration of the Upper Limbs Alters Transmission Along Spinal but Not Corticospinal Pathways",

abstract = "The use of upper limb vibration (ULV) during exercise and rehabilitation continues to gain popularity as a modality to improve function and performance. Currently, a lack of knowledge of the pathways being altered during ULV limits its effective implementation. Therefore, the aim of this study was to investigate whether indirect ULV modulates transmission along spinal and corticospinal pathways that control the human forearm. All measures were assessed under CONTROL (no vibration) and ULV (30 Hz; 0.4 mm displacement) conditions while participants maintained a small contraction of the right flexor carpi radialis (FCR) muscle. To assess spinal pathways, Hoffmann reflexes (H-reflexes) elicited by stimulation of the median nerve were recorded from FCR with motor response (M-wave) amplitudes matched between conditions. An H-reflex conditioning paradigm was also used to assess changes in presynaptic inhibition by stimulating the superficial radial (SR) nerve (5 pulses at 300Hz) 37 ms prior to median nerve stimulation. Cutaneous reflexes in FCR elicited by stimulation of the SR nerve at the wrist were also recorded. To assess corticospinal pathways, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation of the contralateral motor cortex were recorded from the right FCR and biceps brachii (BB). ULV significantly reduced H-reflex amplitude by 15.7% for both conditioned and unconditioned reflexes (24.0 ± 15.7 vs. 18.4 ± 11.2% Mmax; p <0.05). Middle latency cutaneous reflexes were also significantly reduced by 20.0% from CONTROL (−1.50 ± 2.1% Mmax) to ULV (−1.73 ± 2.2% Mmax; p <0.05). There was no significant effect of ULV on MEP amplitude (p > 0.05). Therefore, ULV inhibits cutaneous and H-reflex transmission without influencing corticospinal excitability of the forearm flexors suggesting increased presynaptic inhibition of afferent transmission as a likely mechanism. A general increase in inhibition of spinal pathways with ULV may have important implications for improving rehabilitation for individuals with spasticity (SCI, stroke, MS, etc.).",

keywords = "Human Neuroscience, indirect vibration, H-reflex, cutaneous reflex, motor evoked potential, electromyography, transcranial magnetic stimulation, sensorimotor integration, upper limb vibration, Transcranial magnetic stimulation, Upper Limb Vibration, Motor Evoked Potential, Cutaneous Reflex, Sensorimotor Integration, Indirect Vibration, Electromyography",

author = "Barss, {Trevor S.} and Collins, {David F.} and Dylan Miller and Pujari, {Amit N.}",

note = "Funding Support for this research was provided by the Churchill Travelling Fellowship through Winston Churchill Memorial Trust (to AP) and a Campus Alberta Neuroscience Postdoctoral Fellowship (TB). The vibration stimulation device used in this work was supported by funding from the Scottish Funding Council, United Kingdom (SFC) (to AP). Acknowledgments The authors wish to acknowledge the participants for their contributions during data acquisition.",

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AU - Barss, Trevor S.

AU - Collins, David F.

AU - Miller, Dylan

AU - Pujari, Amit N.

N1 - Funding Support for this research was provided by the Churchill Travelling Fellowship through Winston Churchill Memorial Trust (to AP) and a Campus Alberta Neuroscience Postdoctoral Fellowship (TB). The vibration stimulation device used in this work was supported by funding from the Scottish Funding Council, United Kingdom (SFC) (to AP). Acknowledgments The authors wish to acknowledge the participants for their contributions during data acquisition.

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N2 - The use of upper limb vibration (ULV) during exercise and rehabilitation continues to gain popularity as a modality to improve function and performance. Currently, a lack of knowledge of the pathways being altered during ULV limits its effective implementation. Therefore, the aim of this study was to investigate whether indirect ULV modulates transmission along spinal and corticospinal pathways that control the human forearm. All measures were assessed under CONTROL (no vibration) and ULV (30 Hz; 0.4 mm displacement) conditions while participants maintained a small contraction of the right flexor carpi radialis (FCR) muscle. To assess spinal pathways, Hoffmann reflexes (H-reflexes) elicited by stimulation of the median nerve were recorded from FCR with motor response (M-wave) amplitudes matched between conditions. An H-reflex conditioning paradigm was also used to assess changes in presynaptic inhibition by stimulating the superficial radial (SR) nerve (5 pulses at 300Hz) 37 ms prior to median nerve stimulation. Cutaneous reflexes in FCR elicited by stimulation of the SR nerve at the wrist were also recorded. To assess corticospinal pathways, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation of the contralateral motor cortex were recorded from the right FCR and biceps brachii (BB). ULV significantly reduced H-reflex amplitude by 15.7% for both conditioned and unconditioned reflexes (24.0 ± 15.7 vs. 18.4 ± 11.2% Mmax; p <0.05). Middle latency cutaneous reflexes were also significantly reduced by 20.0% from CONTROL (−1.50 ± 2.1% Mmax) to ULV (−1.73 ± 2.2% Mmax; p <0.05). There was no significant effect of ULV on MEP amplitude (p > 0.05). Therefore, ULV inhibits cutaneous and H-reflex transmission without influencing corticospinal excitability of the forearm flexors suggesting increased presynaptic inhibition of afferent transmission as a likely mechanism. A general increase in inhibition of spinal pathways with ULV may have important implications for improving rehabilitation for individuals with spasticity (SCI, stroke, MS, etc.).

AB - The use of upper limb vibration (ULV) during exercise and rehabilitation continues to gain popularity as a modality to improve function and performance. Currently, a lack of knowledge of the pathways being altered during ULV limits its effective implementation. Therefore, the aim of this study was to investigate whether indirect ULV modulates transmission along spinal and corticospinal pathways that control the human forearm. All measures were assessed under CONTROL (no vibration) and ULV (30 Hz; 0.4 mm displacement) conditions while participants maintained a small contraction of the right flexor carpi radialis (FCR) muscle. To assess spinal pathways, Hoffmann reflexes (H-reflexes) elicited by stimulation of the median nerve were recorded from FCR with motor response (M-wave) amplitudes matched between conditions. An H-reflex conditioning paradigm was also used to assess changes in presynaptic inhibition by stimulating the superficial radial (SR) nerve (5 pulses at 300Hz) 37 ms prior to median nerve stimulation. Cutaneous reflexes in FCR elicited by stimulation of the SR nerve at the wrist were also recorded. To assess corticospinal pathways, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation of the contralateral motor cortex were recorded from the right FCR and biceps brachii (BB). ULV significantly reduced H-reflex amplitude by 15.7% for both conditioned and unconditioned reflexes (24.0 ± 15.7 vs. 18.4 ± 11.2% Mmax; p <0.05). Middle latency cutaneous reflexes were also significantly reduced by 20.0% from CONTROL (−1.50 ± 2.1% Mmax) to ULV (−1.73 ± 2.2% Mmax; p <0.05). There was no significant effect of ULV on MEP amplitude (p > 0.05). Therefore, ULV inhibits cutaneous and H-reflex transmission without influencing corticospinal excitability of the forearm flexors suggesting increased presynaptic inhibition of afferent transmission as a likely mechanism. A general increase in inhibition of spinal pathways with ULV may have important implications for improving rehabilitation for individuals with spasticity (SCI, stroke, MS, etc.).

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KW - Motor Evoked Potential

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KW - Sensorimotor Integration

KW - Indirect Vibration

KW - Electromyography

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DO - 10.3389/fnhum.2021.617669

M3 - Article

SN - 1662-5161

VL - 15

JO - Frontiers in Human Neuroscience

JF - Frontiers in Human Neuroscience

M1 - 617669

ER -

Indirect Vibration of the Upper Limbs Alters Transmission Along Spinal but Not Corticospinal Pathways

Abstract

Bibliographical note

Keywords

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