Paired associative stimulation on the soleus H-Reflex using motor point and peripheral nerve stimulation

Kai Lon Fok; Naotsugu Kaneko; Shirin Tajali; Kei Masani

doi:10.1016/j.neulet.2023.137070

Paired associative stimulation on the soleus H-Reflex using motor point and peripheral nerve stimulation

Neurosci Lett. 2023 Feb 16:797:137070. doi: 10.1016/j.neulet.2023.137070. Epub 2023 Jan 12.

Authors

Kai Lon Fok¹, Naotsugu Kaneko², Shirin Tajali³, Kei Masani⁴

Affiliations

¹ Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9, Canada; KITE, Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON M4G 3V9, Canada.
² Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9, Canada; KITE, Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON M4G 3V9, Canada; Japan Society for the Promotion of Science, Tokyo 102-0083, Japan; Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan.
³ KITE, Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON M4G 3V9, Canada.
⁴ Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9, Canada; KITE, Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON M4G 3V9, Canada. Electronic address: k.masani@utoronto.ca.

PMID: 36641045
DOI: 10.1016/j.neulet.2023.137070

Abstract

Paired associative stimulation (PAS) has been shown to modulate the corticospinal excitability via spike timing dependent plasticity (STDP). In this study, we aimed to suppress the spinal H-Reflex using PAS. We paired two stimulation modalities, i.e., peripheral nerve stimulation (PNS) and motor point stimulation (MPS). We used PNS to dominantly activate the Ia sensory axon, and we used MPS to dominantly activate the α-motoneuron cell body antidromically. Thus, we applied both PNS and MPS such that the α-motoneuron cell body was activated 5 ms before the activation of the Ia sensory axon ending at the Ia-α motoneuron synapse. If the spinal reflexes can be modulated by STDP, and a combination of MPS and PNS is timed appropriately, then the H-Reflex amplitude will decrease while no change in H-Reflex amplitude is expected for MPS or PNS only. To test this hypothesis, six young healthy participants (5M/1F: 26.8 ± 4.1 yrs) received one of the three following conditions on days separated by at least 24 hr: 1) PAS, 2) MPS only or 3) PNS only. The H-Reflex and M-wave recruitment curves of the soleus were measured immediately prior to, immediately after, 30 min and 60 min after the intervention. The normalized H-Reflex amplitudes were then compared across conditions and times using a two-way ANOVA (3 conditions × 4 times). No main effects of condition or time, or interaction effect were found. These results suggest that relying solely on STDP may be insufficient to inhibit the soleus H-Reflex.

Keywords: H-reflex; Motor point stimulation; Paired associative stimulation; Peripheral nerve stimulation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Electric Stimulation / methods
Electromyography / methods
H-Reflex* / physiology
Humans
Motor Neurons / physiology
Muscle, Skeletal / physiology
Peripheral Nerves
Transcutaneous Electric Nerve Stimulation*