# Adaptation of internal motor copy circuits in recovery after spinal cord injury.

> **NIH NIH R01** · TEMPLE UNIV OF THE COMMONWEALTH · 2024 · $527,136

## Abstract

Abstract:
Spinal cord injuries (SCI) affect approximately 100,000 patients each year and causes motor,
sensory and autonomic dysfunction. Approximately 55% of all SCIs occur at the cervical level in
human patients that effect forelimb. Patients effected by a cervical SCI desire recovery of hand
and digit function to improve their current lifestyle. However, the majority of spinal cord injury
models study the functional recovery associates with locomotion after thoracic lesions and not
skilled forelimb patterning after cervical injuries. In general, skilled forelimb patterning is
mediated through the corticospinal tract with support from indirect brainstem regions. Lesions
that cut the corticospinal tract show significant loss of forelimb patterning; however, when the
indirect pathways are preserved, rehabilitative training supports the recovery of the lost function.
We show that this recovery is mediated by C3-C4 propriospinal neurons, a unique propriospinal
neuron normally involved in the formation of an internal motor copy to correct movement errors
during the movement. In this pathway, error correction is mediated by C3-C4 PN axons
terminating onto neurons in the lateral reticular nucleus, a pre-cerebellar nucleus. Information is
then routed through the cerebellum where the motor plan is compared to proprioceptive sensory
information from the forelimb and back to brainstem motor control regions for execution. We
hypothesize that after cervical injury this pathway undergoes rehabilitative adaptation to
compensate for loss of the CST. Here we will take a systems approach to interrogate three
components required for error correction and adaptation of this pathway. The first aim will
examine the integration of information from several forelimb control pathways into the LRN and
if modulation of LRN neuronal activity during rehabilitation augments recovery. The second aim
will investigate the role of unconscious proprioceptive sensory information in rehabilitative
recovery of injury. The third aim, will investigate the cerebellar efferent pathways connecting to
know reticular regions involved in forelimb movements to determine their importance in driving
recovery and error correction after cervical injury and during rehabilitation. Ultimately, this study
will provide essential data to identify the pathways involved in rehabilitative recovery of skilled
forelimb patterning after spinal cord injury and if recovery can be enhanced by activity
dependent modulation during rehabilitative training.

## Key facts

- **NIH application ID:** 10875520
- **Project number:** 5R01NS117749-05
- **Recipient organization:** TEMPLE UNIV OF THE COMMONWEALTH
- **Principal Investigator:** George M Smith
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $527,136
- **Award type:** 5
- **Project period:** 2020-08-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10875520

## Citation

> US National Institutes of Health, RePORTER application 10875520, Adaptation of internal motor copy circuits in recovery after spinal cord injury. (5R01NS117749-05). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10875520. Licensed CC0.

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