Anatomical and electrophysiological plasticity of locomotor networks following spinal transection in the salamander

Neurosci Bull, 2013 · DOI: 10.1007/s12264-013-1363-6 · Published: August 1, 2013

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

This review discusses how salamanders can regain the ability to move after a spinal cord injury. Unlike mammals, salamanders can regenerate nerve fibers in the spinal cord, allowing them to recover some movement. The review focuses on the changes in the spinal cord that allow the salamander to walk and swim again. Understanding these changes could help in developing treatments for spinal cord injuries in humans. Researchers study the electrical activity and structure of nerve cells in the salamander spinal cord to understand how the locomotor networks are rebuilt after injury. This includes looking at how nerve signals are transmitted and how muscles are reactivated.

Study Duration

Up to 500 days

Participants

Adult salamanders

Evidence Level

Review of experimental studies

Key Findings

1
Salamanders can recover locomotor function after complete spinal cord transection due to the regeneration of descending pathways.
2
Regenerated axons from glutamatergic and serotoninergic neurons contribute to the re-activation of locomotor networks below the lesion.
3
Motoneuron excitability is modulated by acetylcholine, and spinalization leads to changes in motoneuron gain and the expression of plateau potentials.

Research Summary

This review provides an overview of the anatomical and electrophysiological changes occurring within the spinal cord that lead to, or are associated with the re-expression of locomotion in spinally-transected salamanders. The extent of regenerated axons exceeds 10 mm after a sufficiently long recovery time (>6 months post-transection). The adult salamander is an excellent experimental model to study the post-lesional plasticity of motor systems in vertebrates.

Practical Implications

Therapeutic Approaches

Understanding the mechanisms of locomotor recovery in salamanders can inform the development of therapeutic approaches for spinal cord injuries in humans.

Targeted Rehabilitation

Identifying the specific neuronal events induced by training during swimming and stepping can help design targeted rehabilitation strategies.

Neuromodulation Strategies

Modulating the excitability of spinal motoneurons and restoring the balance between various transmitter systems can improve locomotor recovery.

Study Limitations

1
Behavioral and kinematic analysis cannot accurately infer the participation of regenerated axons.
2
The number of regenerated axons is lower than in intact animals, leading to imperfect recovery.
3
Inappropriate incorporation of regenerated axons into the sub-lesional spinal networks may occur.

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