Muscle Stimulation: Researchers See the Light

Researchers at Stanford University have successfully used light signals to stimulate muscle activity in mice. The concepts used in the experiment could one day form the basis of medical treatment for humans with a range of muscle-related conditions, including reversing the process to reduce involuntary muscle spasms.

The experiment began with using an algae-derived gene that was known to be responsive to light. This gene was inserted into the mice, leading to a light-sensitive protein forming on the surface of their nerve cells.

The researchers then placed a ring around each mouse, concentrating on the sciatic nerve. Each ring had a series of LEDs facing towards the mouse. They found that short bursts of blue light caused the nerve to induce muscle contractions.

Gizmag reports that the breakthrough is in the details of how this work. Previous tests using electrical impulses have worked to a limited extent on humans and animals, but only for a short time. That’s because the electricity was stimulating a particular type of nerve that is used for brief and intensive activity such as running. This meant the muscles those nerves stimulated were quickly exhausted. The light technique instead stimulates nerves associated with slower muscle activity.

To find the effects of this difference, the researchers also tested the electrical technique on the same mice. They found this lead to the muscles becoming exhausted after around four minutes, whereas with the light technique, the muscles still worked (albeit at around a third the peak force) after at least 20 minutes.

(Image for illustration only. Credit: Kappa Windscreens)

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