Turning off the Brain With Light

In 2005, Stanford scientist Karl Deisseroth discovered how to switch individual brain cells on and off by using light in a technique he dubbed 'optogenetics'.

Research teams around the world have since used this technique to study brain cells, heart cells, stem cells and others regulated by electrical signals.

However, light-sensitive proteins were efficient at switching cells on but proved less effective at turning them off.

Now, after almost a decade of research, scientists have been able to shut down the neurons as well as activate them.