Functional regeneration following spinal transection demonstrated in the isolated spinal cord of the larval sea lamprey

Proc. Nati. Acad. Sci. USA, 1986 · DOI: · Published: April 1, 1986

Neurology Rehabilitation Regenerative Medicine & Stem Cells

Simple Explanation

This study investigates spinal cord regeneration in larval sea lampreys after a complete spinal cord transection. The researchers examined whether the regenerated axons could form functional synaptic connections that contribute to coordinated swimming behavior. To test this, the researchers induced 'fictive' swimming in the isolated spinal cord by adding D-glutamate. They then monitored ventral root discharges above and below the healed transection site. The results showed a high degree of phase-locking between segments above and below the transection, suggesting that the behavioral recovery is mediated by regenerated functional synaptic connections responsible for intersegmental coordination during locomotion.

Study Duration

2-6 months

Participants

8 larvae with spinal transection, 3 control larvae

Evidence Level

Not specified

Key Findings

1
Axons in the larval sea lamprey can regenerate across the site of a spinal cord transection and form functioning synapses with some of their normal target neurons.
2
Ventral root discharges of segments above and below a healed transection showed a high degree of phase-locking.
3
The regenerated neural tissue can coordinate the swimming motor pattern across the healed transection site.

Research Summary

The study demonstrates that axons in larval sea lampreys can regenerate across a spinal cord transection and form functional synapses. Fictive swimming induced in isolated spinal cords showed phase-locking between segments above and below the transection, indicating functional synaptic connections mediate intersegmental coordination. The findings suggest that behavioral recovery after spinal transection in lampreys results from functional regeneration of the central pattern generator (CPG) for locomotion.

Practical Implications

Understanding Regeneration Mechanisms

The study provides insights into the mechanisms of spinal cord regeneration and functional recovery in a vertebrate model system.

Potential for Therapeutic Applications

The findings suggest that promoting axonal regeneration and synapse formation could be a viable strategy for restoring motor function after spinal cord injury.

Implications for Mammalian Spinal Cord Injury

The research suggests that even limited axonal regeneration in mammals could potentially restore some coordinated motor function.

Study Limitations

1
The identity nor the specificity of the reconnections is addressed by these experiments.
2
The regenerated coupling is probably not as strong as that in the untransected cord.
3
Sensory feedback could increase the coupling and thus explain why normal-appearing swimming is recovered following transection.

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