A Light Switch for the Brain
A light-triggered switch to control brain cells could aid in the development of therapies for depression, Parkinson’s, epilepsy, and other neurological diseases
Sources: “Multimodal Fast Optical Interrogation of Neural Circuitry”
Feng Zhang et al.
Nature 446: 633-639
“Multiple-Color Optical Activation, Silencing, and Desynchronization of Neural Activity, with Single-Spike Temporal Resolution”
Xue Han and Edward S. Boyden
PLoS One, March 21, 2007
Results: Scientists at MIT and Stanford University have independently created a light-controlled molecular switch that can turn off electrical activity in neurons. By combining it with a similar, previously developed switch that can trigger electrical activity, neuroscientists can now use light to turn specific neural circuits on and off.
Why it matters: The new neural switch enables unprecedented control over the brain and could lead to more-effective therapies for epilepsy, Parkinson’s, depression, and other brain diseases. The neural switch could also serve as a research tool to help neuroscientists decipher the language of the brain–the information, encoded in the electrical activity of neurons, that forms our memories and directs our every move.
Methods: To create the new neural switch, researchers borrowed a gene from a lake-dwelling microörganism; the gene codes for a light-sensitive protein that pumps chloride ions. One study showed that the chloride-ion pump can be genetically engineered into specific neurons in the brain or into muscle cells. When one of these genetically modified cells is hit with yellow light, the pump brings a negative charge into it, preventing it from firing.
Next Steps: The scientists are now using the two switches in animals genetically engineered to model epilepsy, depression, and Parkinson’s disease. The hope is to find neural cells whose activity or inactivity is responsible for symptoms characteristic of those diseases, including seizures in epilepsy. Such findings could aid in the development of drugs targeted to only those cells; one day, light-activated implants might replace the electrodes used in treatments such as deep brain stimulation.