PMID- 37646076
OWN - NLM
STAT- MEDLINE
DCOM- 20230925
LR  - 20231003
IS  - 1522-1598 (Electronic)
IS  - 0022-3077 (Linking)
VI  - 130
IP  - 4
DP  - 2023 Oct 1
TI  - Identifying spinal tracts transmitting distant effects of trans-spinal magnetic 
      stimulation.
PG  - 883-894
LID - 10.1152/jn.00202.2023 [doi]
AB  - Estimating the state of tract-specific inputs to spinal motoneurons is critical 
      to understanding movement deficits induced by neurological injury and potential 
      pathways to recovery but remains challenging in humans. In this study, we 
      explored the capability of trans-spinal magnetic stimulation (TSMS) to modulate 
      distal reflex circuits in young adults. TSMS was applied over the thoracic spine 
      to condition soleus H-reflexes involving sacral-level motoneurons. Three TSMS 
      intensities below the motor threshold were applied at interstimulus intervals 
      (ISIs) between 2 and 20 ms relative to peripheral nerve stimulation (PNS). 
      Although low-intensity TSMS yielded no changes in H-reflexes across ISIs, the two 
      higher stimulus intensities yielded two phases of H-reflex inhibition: a 
      relatively long-lasting period at 2- to 9-ms ISIs, and a short phase at 11- to 
      12-ms ISIs. H-reflex inhibition at 2-ms ISI was uniquely dependent on TSMS 
      intensity. To identify the candidate neural pathways contributing to H-reflex 
      suppression, we constructed a tract-specific conduction time estimation model. 
      Based upon our model, H-reflex inhibition at 11- to 12-ms ISIs is likely a 
      manifestation of orthodromic transmission along the lateral reticulospinal tract. 
      In contrast, the inhibition at 2-ms ISI likely reflects orthodromic transmission 
      along sensory fibers with activation reaching the brain, before descending along 
      motor tracts. Multiple pathways may contribute to H-reflex modulation between 4- 
      and 9-ms ISIs, orthodromic transmission along sensorimotor tracts, and antidromic 
      transmission of multiple motor tracts. Our findings suggest that noninvasive TSMS 
      can influence motoneuron excitability at distal segments and that the 
      contribution of specific tracts to motoneuron excitability may be distinguishable 
      based on conduction velocities.NEW & NOTEWORTHY This study explored the 
      capability of trans-spinal magnetic stimulation (TSMS) over the thoracic spine to 
      modulate distal reflex circuits, H-reflexes involving sacral-level motoneurons, 
      in young adults. TSMS induced two inhibition phases of H-reflex across 
      interstimulus intervals (ISIs): a relatively long-lasting period at 2- to 9-ms 
      ISIs, and a short phase at 11- to 12-ms ISIs. An estimated probability model 
      constructed from tract-specific conduction velocities allowed the identification 
      of potential spinal tracts contributing to the changes in motoneuron 
      excitability.
FAU - Chung, Yu-Chen
AU  - Chung YC
AUID- ORCID: 0000-0001-8408-4341
AD  - Department of Physical Medicine and Rehabilitation, UT Southwestern Medical 
      Center, Dallas, Texas, United States.
FAU - Shemmell, Jonathan
AU  - Shemmell J
AUID- ORCID: 0000-0002-4575-133X
AD  - School of Medical, Indigenous and Health Sciences, Faculty of Science, Medicine 
      and Health, University of Wollongong, Wollongong, Australia.
FAU - Kumala, Caitlin
AU  - Kumala C
AD  - Department of Biology, University of Texas at Dallas, Richardson, Texas, United 
      States.
FAU - Soedirdjo, Subaryani D H
AU  - Soedirdjo SDH
AUID- ORCID: 0000-0002-8523-5639
AD  - Department of Physical Medicine and Rehabilitation, UT Southwestern Medical 
      Center, Dallas, Texas, United States.
FAU - Dhaher, Yasin Y
AU  - Dhaher YY
AUID- ORCID: 0000-0003-1504-3233
AD  - Department of Physical Medicine and Rehabilitation, UT Southwestern Medical 
      Center, Dallas, Texas, United States.
AD  - Department of Bioengineering, University of Texas at Dallas, Richardson, Texas, 
      United States.
AD  - Peter O'Donnell Jr. Brain Institute, UT Southwestern Medical Center, Dallas, 
      Texas, United States.
LA  - eng
SI  - figshare/10.6084/m9.figshare.23934981
GR  - R01 AR069176/AR/NIAMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
DEP - 20230830
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
SB  - IM
MH  - Humans
MH  - Young Adult
MH  - *Brain
MH  - *Sacrum
MH  - Motor Neurons
MH  - Neurons, Efferent
MH  - Light
OTO - NOTNLM
OT  - ascending pathways
OT  - descending pathways
OT  - magnetic stimulation
OT  - motoneurones
OT  - spinal neurophysiology
EDAT- 2023/08/30 06:48
MHDA- 2023/09/25 06:42
CRDT- 2023/08/30 04:06
PHST- 2023/09/25 06:42 [medline]
PHST- 2023/08/30 06:48 [pubmed]
PHST- 2023/08/30 04:06 [entrez]
AID - 10.1152/jn.00202.2023 [doi]
PST - ppublish
SO  - J Neurophysiol. 2023 Oct 1;130(4):883-894. doi: 10.1152/jn.00202.2023. Epub 2023 
      Aug 30.