Potentiating paired corticospinal-motoneuronal plasticity after spinal cord injury

Karen L. Bunday, M. A. Urbin, Monica A Perez*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Background: Paired corticospinal-motoneuronal stimulation (PCMS) increases corticospinal transmission in humans with chronic incomplete spinal cord injury (SCI). Objective/Hypothesis: Here, we examine whether increases in the excitability of spinal motoneurons, by performing voluntary activity, could potentiate PCMS effects on corticospinal transmission. Methods: During PCMS, we used 100 pairs of stimuli where corticospinal volleys evoked by transcranial magnetic stimulation (TMS) over the hand representation of the primary motor cortex were timed to arrive at corticospinal-motoneuronal synapses of the first dorsal interosseous (FDI) muscle ∼1–2 ms before antidromic potentials were elicited in motoneurons by electrical stimulation of the ulnar nerve. PCMS was applied at rest (PCMS rest ) and during a small level of isometric index finger abduction (PCMS active ) on separate days. Motor evoked potentials (MEPs) elicited by TMS and electrical stimulation were measured in the FDI muscle before and after each protocol in humans with and without (controls) chronic cervical SCI. Results: We found in control participants that MEPs elicited by TMS and electrical stimulation increased to a similar extent after both PCMS protocols for ∼30 min. Whereas, in humans with SCI, MEPs elicited by TMS and electrical stimulation increased to a larger extent after PCMS active compared with PCMS rest . Importantly, SCI participants who did not respond to PCMS rest responded after PCMS active and those who responded to both protocols showed larger increments in corticospinal transmission after PCMS active . Conclusions: Our findings suggest that muscle contraction during PCMS potentiates corticospinal transmission. PCMS applied during voluntary activity may represent a strategy to boost spinal plasticity after SCI.

Original languageEnglish (US)
Pages (from-to)1083-1092
Number of pages10
JournalBrain Stimulation
Volume11
Issue number5
DOIs
StatePublished - Sep 1 2018

Funding

We thank the spinal cord injury individuals for their participation in this study. Funding: This work was supported by funding from the National Institute of Neurological Disorders and Stroke – National Institutes of Health (NINDS R01 NS090622 , NINDS R01 NS076589 ) and the Department of Veterans Affairs (Veteran Affairs RR&D Merit Review I01RX002474 , Veterans Affairs RR&D Merit Review I01RX001807 ).

Keywords

  • Corticospinal
  • Corticospinal-motoneuronal
  • Neurophysiology
  • Neuroplasticity
  • Spike-timing dependent plasticity
  • Spinal cord injury

ASJC Scopus subject areas

  • Biophysics
  • General Neuroscience
  • Clinical Neurology

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