Peripheral neural interfaces: Skeletal muscles are hyper-reinnervated according to the axonal capacity of the surgically rewired nerves

Science Advances, 2024 · DOI: 10.1126/sciadv.adj3872 · Published: February 28, 2024

Simple Explanation

Researchers emulated clinical scenarios by surgically rewiring nerves with high or low neural capacity to the sternomastoid muscle in rats. They found that the muscle could be hyper-reinnervated, meaning it could form many more neuromuscular junctions than it normally would. The type of nerve influenced the muscle's characteristics, altering the expression of myosin heavy-chain types to match the donor nerve.

Study Duration

12 weeks

Participants

69 Sprague-Dawley rats

Evidence Level

Not specified

Key Findings

1
Skeletal muscle can be reinnervated by a number of axons multiple times its initial physiological innervation.
2
A single target muscle can incorporate a 15-fold amount of its original innervating axons after a high-capacity nerve transfer.
3
Different neuronal sources can redefine the molecular profile of the muscle fiber types, indicating changes in the muscle physiology.

Research Summary

This study investigates the capacity of skeletal muscles to act as biological amplifiers of neural information by surgically rewiring nerves with varying neural capacities to a target muscle. The results demonstrate that muscles can be hyper-reinnervated, with a high-capacity nerve transfer leading to a 15-fold increase in neuromuscular junctions. The study highlights the potential of skeletal muscles to express high-dimensional neural function for advanced man-machine interfaces.

Practical Implications

Prosthetic Limb Control

Skeletal muscles can integrate a multifold neural input compared to their original supply, enabling more elaborate control of prosthetic devices.

Neural Signal Amplification

Targeted muscle reinnervation can be performed by transferring a high neural input load to a single target muscle, creating a high-fidelity bioscreen for neuromuscular interfaces.

Clinical Translation

The findings provide a neurobiological basis for translating the approach of nerve transfers and myoelectric signal processing to patients with amputations and limited muscle tissue.

Study Limitations

1
Deciphering patients’ complex movement intents remains a challenging issue.
2
Decoding the high-density neural information distributed within one single muscle requires advanced interfacing systems.
3
The study was performed on rats, further research is needed to translate these findings to humans.

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