Cortical and subcortical effects of transcutaneous spinal cord stimulation in humans with tetraplegia

Francisco D. Benavides, Hang Jin Jo, Henrik Lundell, V. Reggie Edgerton, Yuri Gerasimenko, Monica A. Perez*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

An increasing number of studies supports the view that transcutaneous electrical stimulation of the spinal cord (TESS) promotes functional recovery in humans with spinal cord injury (SCI). However, the neural mechanisms contributing to these effects remain poorly understood. Here we examined motor-evoked potentials in arm muscles elicited by cortical and subcortical stimulation of corticospinal axons before and after 20 min of TESS (30 Hz pulses with a 5 kHz carrier frequency) and sham-TESS applied between C5 and C6 spinous processes in males and females with and without chronic incomplete cervical SCI. The amplitude of subcortical, but not cortical, motorevoked potentials increased in proximal and distal arm muscles for 75 min after TESS, but not sham-TESS, in control subjects and SCI participants, suggesting a subcortical origin for these effects. Intracortical inhibition, elicited by paired stimuli, increased after TESS in both groups. When TESS was applied without the 5 kHz carrier frequency both subcortical and cortical motor-evoked potentials were facilitated without changing intracortical inhibition, suggesting that the 5 kHz carrier frequency contributed to the cortical inhibitory effects. Hand and arm function improved largely when TESS was used with, compared with without, the 5 kHz carrier frequency. These novel observations demonstrate that TESS influences cortical and spinal networks, having an excitatory effect at the spinal level and an inhibitory effect at the cortical level. We hypothesized that these parallel effects contribute to further the recovery of limb function following SCI.

Original languageEnglish (US)
Pages (from-to)2633-2643
Number of pages11
JournalJournal of Neuroscience
Volume40
Issue number13
DOIs
StatePublished - Mar 25 2020

Keywords

  • Corticospinal
  • Intracortical inhibition
  • Neurophysiology
  • Neuroplasticity
  • Spinal cord injury
  • Spinal networks

ASJC Scopus subject areas

  • Neuroscience(all)

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