PLASTICITY IN THE SPINAL CORD SENSORY MAP FOLLOWING PERIPHERAL NERVE INJURY IN RATS

The Journal of Neuroscience, 1981 · DOI: · Published: July 1, 1981

Simple Explanation

This study investigates how the sensory map in the spinal cord changes after nerves in the leg are cut in rats. Normally, a specific area of the spinal cord processes signals from the toes and foot. After the nerves are cut, that area of the spinal cord starts responding to signals from other parts of the leg, like the thigh. This means the spinal cord is reorganizing itself. Interestingly, if the cut nerves are repaired, the spinal cord goes back to processing signals from the toes and foot, showing that this change is reversible. However, if the nerves are only damaged (crushed) and not cut, this reorganization doesn't happen.

Study Duration

2-147 days

Participants

Adult (250- to 350-gm) male rats of the Wistar-derived Sabra strain

Evidence Level

Not specified

Key Findings

1
Peripheral nerve transection leads to a reorganization of the spinal cord sensory map, with deafferented cells acquiring novel receptive fields on the thigh, lower back, or perineum.
2
This reorganization is reversible upon nerve regeneration, as toe-foot afferents regain exclusive dominance of the medial dorsal horn.
3
Reorganization occurs after nerve transection, ligation, or ligation with distal transection, but not if the nerve is crushed.

Research Summary

The study demonstrates that the somatotopic mapping of medial dorsal horn cells in rats changes within 4-5 days after peripheral transection of afferents, leading to novel receptive fields. Afferents from nearby intact nerves of the thigh come to drive the cells and provide them with a novel receptive field on the skin proximal to the ankle. This change is largely reversed if the cut nerve regenerates, but reorganization does not occur if the toe-foot nerves are crushed but not cut.

Practical Implications

Understanding Pain Mechanisms

The findings shed light on how the spinal cord adapts after nerve injury, which may have implications for understanding chronic pain development.

Rehabilitation Strategies

The reversibility of the sensory map reorganization suggests potential targets for rehabilitation strategies aimed at restoring normal sensory processing after nerve damage.

Developing Targeted Therapies

Identifying the signals that trigger synaptic reorganization could lead to the development of therapies that prevent or reverse maladaptive plasticity in the spinal cord.

Study Limitations

1
The study was conducted on rats, and the findings may not directly translate to humans.
2
The exact mechanisms underlying the synaptic reorganization remain uncertain.
3
The study focuses on a specific type of nerve injury (sciatic and saphenous nerve transection) and may not generalize to other types of nerve injuries.

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