# Preservation of sensory la afferent boutons on motoneurons after peripheral nerve injury restores synaptic transmissions and rescues whole limb kinematics

> **NIH NIH F32** · GEORGIA INSTITUTE OF TECHNOLOGY · 2021 · $33,195

## Abstract

Following peripheral nerve injury (PNI), both sensory and motoneuron (MN) axons degenerate at the site of
injury, but both regenerate to their muscle targets. Motoneurons regain the ability to produce muscle force and
almost half of group Ia muscle proprioceptors reinnervate muscle spindles and fire in response to changes in
muscle length. However, one deficit that remains after PNI is that the central projecting branch of the Ia
afferents that forms monosynaptic connections with the MNs dies back and disconnects from the motor pool,
never to return even with provisionally successful reinnervation of muscle spindle receptors. This synaptic
retraction has a major impact on common motor activities as the central motor network losses the feedback
mechanism necessary for postural adjustments. This Ia synaptic loss is dependent on a pro-inflammatory
immune response in the ventral horn of the spinal cord. However, suppressing the immune response using the
broad-spectrum antibiotic minocycline, completely prevents the structural loss of Ia afferent inputs on
axotomized MNs. However, the major questions remain, “are these preserved synaptic inputs functional?” and
“does preservation of Ia’s improve recovery of motor behavior?” Objective: Investigate synaptic function
and motor behavior when the connections between Ia afferents and MNs are preserved following PNI.
Specific Aim 1, Hypothesis: Rescuing Ia - MN spinal circuit network will promote recovery of limb
movement.
Specific Aim 2, Hypothesis: Physical preservation will rescue function at synapses made by Ia
afferents on motoneurons.
Specific Aim 3, Hypothesis: Amplification of Ia synaptic current is sufficient to restore sustained firing
in motoneurons after injury.
These aims are designed to systematically interrogate the function of preserved Ia afferent synapses after
nerve injury. All of these experiments will take place at Georgia Tech under the direction of the sponsor, Dr.
Tim Cope, and additional guidance from our collaborator Dr. Young-Hui Chang. Both have provided their
expertise in the development of this project and will oversee the success of all three aims.

## Key facts

- **NIH application ID:** 10462090
- **Project number:** 3F32NS112556-02S1
- **Recipient organization:** GEORGIA INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** Travis Michael Rotterman
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $33,195
- **Award type:** 3
- **Project period:** 2019-09-30 → 2022-03-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10462090

## Citation

> US National Institutes of Health, RePORTER application 10462090, Preservation of sensory la afferent boutons on motoneurons after peripheral nerve injury restores synaptic transmissions and rescues whole limb kinematics (3F32NS112556-02S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10462090. Licensed CC0.

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