How Light Is Helping Scientists Map the Brain
Scientists studying the brain have long faced a challenge: identifying which nerve cells and circuits contribute to particular feelings, behaviours and bodily functions. Optogenetics offers a way to investigate those connections by using light to control electrical activity in selected cells. The approach allows researchers to examine what happens when specific neural pathways are switched on or off.
The method relies on channelrhodopsin, a protein found in algae. In the early 2000s, Hegemann and Nagel discovered the protein and its unusual properties. Deisseroth then developed a way to use the light-controlled protein to activate nerve cells in the brains of mice. These advances gave researchers a means of testing the roles of particular cells within living animals.
Since then, researchers have used optogenetics to investigate nerve cells and pathways in animals. By observing the effects of activating or suppressing a circuit, they can gather evidence about its role in behaviour and other processes. The technique provides a way to move beyond observing brain activity alone and examine how changes in selected cells relate to changes elsewhere.
The Nobel Committee for Physiology or Medicine says the method enables scientists to switch individual neural circuits on or off with light. According to the committee, experiments can probe memories, feelings and behaviours, as well as identify types of neurons involved in psychiatric and neurological disorders. These applications concern research into how circuits operate; they do not, by themselves, establish treatments for those conditions.
The committee also points to research on how the nervous system interacts with cells beyond the brain, including those in the heart and gut. Per Svenningsson, the committee’s chair, described optogenetics as offering possibilities for mapping the brain that were previously out of reach. Its central contribution is an experimental tool for examining connections among cells, circuits and bodily functions.