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Author Notes:

Corresponding author: Trisha M. Kesar, PT, PhD, Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, 1441 Clifton Road NE, Suite 236, Atlanta, GA 30322, USA. Tel.: +1 404 712 5803; tkesar@emory.edu

Acknowledgments: Personnel: Study participants and members of the 2016 DPT Storm student collaborative–Haley Shore, Sarah Sharbaugh, Daniel Schaeffer, Emily Ta, and Sumi Sato.

The authors have no conflicts of interests related to the contents of the manuscript.

Subjects:

Research Funding:

TMK is supported by the National Institute of Child Health and Human Development grant number K01 HD079584.

MRB is supported by the National Institute of Child Health and Human Development grant number K12HD055931 and National Institutes of Health grant number 5R24HD050821-11.

SLW is supported by grants U10NS086607 and U01 NS091951

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Neurosciences
  • Neurosciences & Neurology
  • Activation
  • coactivation
  • lower limb
  • motor evoked potentials
  • neuroplasticity
  • posture
  • TRANSCRANIAL MAGNETIC STIMULATION
  • MOTOR-EVOKED-POTENTIALS
  • SOLEUS MUSCLE
  • ANTAGONISTIC MUSCLES
  • CORTEX
  • STROKE
  • TMS
  • REHABILITATION
  • COCONTRACTION
  • FACILITATION

Effects of posture and coactivation on corticomotor excitability of ankle muscles

Tools:

Journal Title:

Restorative Neurology and Neuroscience

Volume:

Volume 36, Number 1

Publisher:

, Pages 131-146

Type of Work:

Article | Post-print: After Peer Review

Abstract:

BACKGROUND: The use of transcranial magnetic stimulation (TMS) to evaluate corticomotor excitability of lower limb (LL) muscles can provide insights about neuroplasticity mechanisms underlying LL rehabilitation. However, to date, a majority of TMS studies have focused on upper limb muscles. Posture-related activation is an important under-investigated factor influencing corticomotor excitability of LL muscles. OBJECTIVE: The purpose of this study was to evaluate effects of posture and background activation on corticomotor excitability of ankle muscles. METHODS: Fourteen young neurologically-unimpaired participants (26.1±4.1 years) completed the study. TMS-evoked motor evoked potentials (MEPs) were recorded from the tibialis anterior (TA) and soleus during 4 conditions - standing, standing coactivation, sitting, and sitting coactivation. TA and soleus MEP amplitudes were compared during: (1) standing versus sitting;(2) standing coactivation (standing while activating both TA and soleus) versus sitting coactivation; and (3) standing coactivation versus standing. For each comparison, background EMG for TA and soleus were matched. Trial-to-trial coefficient of variation of MEP amplitude and coil-positioning errors were additional dependent variables. RESULTS: No differences were observed in TA or soleus MEP amplitudes during standing versus sitting. Compared to sitting coactivation, larger MEPs were observed during standing coactivation for soleus but not TA. Compared to standing, the standing coactivation task demonstrated larger MEPs and reduced trial-to-trial MEP variability. CONCLUSION: Our findings suggest that incorporation of measurements in standing in future TMS studies may provide novel insights into neural circuits controlling LL muscles. Standing and standing coactivation tasks may be beneficial for obtaining functionally-relevant neuroplasticity assessments of LL musculature.

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©2018 IOS Press All rights reserved.

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