Related Experiment Video
Updated: May 21, 2026
Assessing Functional Recovery of Eupneic Diaphragm Activity Following Unilateral Cervical Spinal Cord Hemisection in Rats
Published on: June 14, 2024
Recovery of inspiratory intercostal muscle activity following high cervical hemisection
B J Dougherty1, K Z Lee, E J Gonzalez-Rothi
1University of Florida, College of Medicine, McKnight Brain Institute, Department of Neuroscience, Gainesville, FL 32611, United States.
Insights
Following unilateral cervical spinal cord injury in rats, respiratory muscle activity recovers robustly. This recovery is driven by plasticity in crossed-intercostal circuitry, restoring function in intercostal muscles on the injured side.
Area of Science:
- Neuroscience
- Respiratory Physiology
Background:
- Thoracic interneurons possess commissural functions, activating contralateral motoneurons.
- Unilateral cervical spinal cord injury may lead to modest impairment of respiratory-related intercostal muscle electromyogram (EMG) activity.
Purpose of the Study:
- To investigate the functional recovery of respiratory-related intercostal (IC) muscle EMG activity after unilateral cervical spinal cord injury.
- To determine if plasticity in crossed-intercostal circuitry contributes to functional recovery.
Main Methods:
- Rats underwent C2 spinal cord hemisection (C2HS).
- Inspiratory tidal volume (VT) and bilateral intercostal EMG activity were recorded at 1-3 days, 2 weeks, and 8 weeks post-injury.
- Data were collected during baseline breathing and a 7% CO(2) challenge.
Main Results:
- A significant reduction in ipsilateral inspiratory intercostal EMG bursting was observed 1-3 days post-C2HS.
- A time-dependent return of ipsilateral EMG activity occurred, reaching control levels by 2 weeks post-injury.
- Increased ipsilateral intercostal EMG activity correlated with increased VT post-injury.
Conclusions:
- Plasticity within crossed-intercostal circuitry enables robust, spontaneous recovery of ipsilateral intercostal activity following C2HS.
- This neural plasticity mitigates the functional impact of unilateral cervical spinal cord injury on respiratory muscles.
Abstract:
Anatomical and neurophysiological evidence indicates that thoracic interneurons can serve a commissural function and activate contralateral motoneurons. Accordingly, we hypothesized that respiratory-related intercostal (IC) muscle electromyogram (EMG) activity would be only modestly impaired by a unilateral cervical spinal cord injury. Inspiratory tidal volume (VT) was recorded using pneumotachography and EMG activity was recorded bilaterally from the 1st to 2nd intercostal space in anesthetized, spontaneously breathing rats. Studies were conducted at 1-3 days, 2 wks or 8 wks following C2 spinal cord hemisection (C2HS). Data were collected during baseline breathing and a brief respiratory challenge (7% CO(2)). A substantial reduction in inspiratory intercostal EMG bursting ipsilateral to the lesion was observed at 1-3 days post-C2HS. However, a time-dependent return of activity occurred such that by 2 wks post-injury inspiratory intercostal EMG bursts ipsilateral to the lesion were similar to age-matched, uninjured controls. The increases in ipsilateral intercostal EMG activity occurred in parallel with increases in VT following the injury (R=0.55; P<0.001). We conclude that plasticity occurring within a "crossed-intercostal" circuitry enables a robust, spontaneous recovery of ipsilateral intercostal activity following C2HS in rats.
