Mice muscles controlled by light
How do you re-animate paralysed limbs? A new approach being trialled on genetically modified mice uses flashes of light.
The modified mice contain a protein from green algae (ChR2) that attaches to the surface of nerve cells.
When the sciatic nerve of anaesthetised mice was stimulated with a flash of light the Achilles tendon contracted.
Previously electrical stimulation has been used to artificially activate muscles, but electricity only stimulates fast fibres in muscles. This causes jerky movements and the muscle quickly tires.
In this case the light-stimulated contractions were much more similar to normal muscle activity with the experimenters able to activate just slow fibres by altering the intensity of light.