A novel device that helps scientists discover the functions of different types of cells in the brain has gone multicolour.
Optogenetics is a technique that allows scientists to control neurons' electrical activity with light by engineering them to express light-sensitive proteins.
Most of these light-sensitive proteins, known as opsins, respond to light in the blue-green range.
Now, a Massachusetts Institute of Technology team has discovered an opsin that is sensitive to red light, which allows researchers to independently control the activity of two populations of neurons at once, enabling much more complex studies of brain function.
"If you want to see how two different sets of cells interact, or how two populations of the same cell compete against each other, you need to be able to activate those populations independently," said Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT.
The new opsin is one of about 60 light-sensitive proteins found in a screen of 120 species of algae.
The research also yielded the fastest opsin, enabling researchers to study neuron activity patterns with millisecond timescale precision.
Opsins occur naturally in many algae and bacteria, which use the light-sensitive proteins to help them respond to their environment and generate energy.
To achieve optical control of neurons, scientists engineer brain cells to express the gene for an opsin, which transports ions across the cell's membrane to alter its voltage.
Using this approach, researchers can selectively turn a population of cells on or off and observe what happens in the brain, said the study appeared in the journal Nature Methods.
