# Influence of neuromodulatory input on ankle control and spasticity in persons with spinal cord injury.

> **NIH NIH F31** · SHEPHERD CENTER · 2022 · $46,752

## Abstract

People with spinal cord injury (SCI) may have some walking ability, however, they are often challenged with a
spastic gait pattern, characterized by poor voluntary control of the muscles that lift the foot (dorsiflexors) and
spasms of the muscles that control push-off (plantar flexors). Both deficits contribute to impaired ability to
achieve foot-ground clearance, making walking laborious and unstable. Two major neural contributors to
spastic gait include disrupted descending corticospinal tract (CST) drive to the ankle dorsiflexors and impaired
modulation of the plantar flexor spinal reflex circuit (SRC). It is still unknown whether diminished descending
volitional drive or impairment of reflex modulation contributes more to spastic gait. Afferent input has a strong
neuromodulatory effect on the excitability of both the CST and SRC. Whole body vibration (WBV) is a robust
form of afferent input that provides a probe to understand the neurophysiologic mechanisms underlying spastic
gait. The long-term goal of this research is to develop rehabilitation strategies to enhance walking function and
mobility in persons with SCI by improving ankle control. The overall objective of this proposal is to understand
the roles of the CST and SRC in volitional and reflex control of the ankle. The rationale for this project is that
understanding the neurophysiological contributions to increased volitional control and decreased spasticity in
the ankles will be the first step to developing important non-invasive rehabilitation strategies to improve spastic
gait in persons with SCI and other upper motor neuron disorders. The central hypothesis is that improvements
in ankle function will have a greater association with changes in the CST than with changes in SRC
modulation, as corticospinal drive influences both volitional control and reflex modulation. Using WBV to
activate cortical and spinal circuits, the central hypothesis will be tested via two specific aims: 1) Determine the
contribution of dorsiflexors CST and plantar flexor SRC excitability to ankle volitional control in individuals with
SCI; and 2) Determine the contribution of dorsiflexors CST and plantar flexor SRC excitability to ankle
spasticity in individuals with SCI. The proposed research is innovative, because there has yet to be a study
examining how an intervention that targets the CST and SRC simultaneously, impacts the different
components of spastic gait after SCI. Understanding the mechanisms underlying spastic gait is significant
because it provides a foundation for the development of targeted non-invasive therapies to increase the
functional outcomes of the people impacted by this impaired gait pattern. Overall, the knowledge gained in this
proposal will provide more insight in the underlying mechanisms of ankle control and spasticity in persons with
SCI.

## Key facts

- **NIH application ID:** 10311060
- **Project number:** 5F31HD101151-03
- **Recipient organization:** SHEPHERD CENTER
- **Principal Investigator:** Jasmine Marie Hope
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $46,752
- **Award type:** 5
- **Project period:** 2019-12-01 → 2022-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10311060

## Citation

> US National Institutes of Health, RePORTER application 10311060, Influence of neuromodulatory input on ankle control and spasticity in persons with spinal cord injury. (5F31HD101151-03). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10311060. Licensed CC0.

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