Science Scene: Optogenetics spotlights the brain

Laura Zhang

Students might wonder what’s going on in their heads when they can’t stop watching Netflix, or how their minds relay the balance between bitter and sweet in their favorite beverage. Optogenetics can illuminate the answers to some of these brain-related questions. 

In this relatively new method, scientists manipulate light to control certain regions of the brain. As part of the BRAIN Initiative launched by President Obama, UT-Austin received grants worth $4 million to advance techniques, including optogenetics, for studying the activity of neurons. Boris Zemelman, a UT professor in the department of neuroscience, received a portion of the overall grant to pursue his research. 

Zemelman, who had developed the earlier approaches for optogenetics over a decade ago, said one of the many advantages
behind this technique is the focus on how neurons interact, rather than just the brain’s anatomy.  

“Once you take the brain apart, however you do it, all of the functions disappear. … You can poke at it and map it, but it’s really just a bundle of wires,” Zemelman said. “And you haven’t learned about the brain yet.”

With previous methods, scientists usually had to pick apart a dead brain to study it. This approach forced researchers to
focus on the mechanics of the brain rather than the interactions between neurons. Optogenetics remedies this problem because light does not destroy the living tissues of the brain. 

In order to perform optogenetics on animals, scientists insert a light-responsive protein into the specific region of the brain they want to study. This protein is never naturally found in the brain — scientists harvest it from the eye, according to a study in the journal of Nature Methods. Since light only activates the region with the inserted protein, researchers can experiment with a certain area of the brain by pulsing light at different frequencies.  

For example, by using optogenetics, scientists have determined the perception of taste depends on the innate wiring of the brain, not experience. So, when a beverage seems too bitter at first, drinking it more often will not sweeten the taste.

However, like any other scientific technique, the value of using optogenetics for a research study depends on the desired outcome of the experiment. Zemelman said optogenetics would not be the optimal method of study in certain situations. For example, since light is instantaneous, researchers may prefer other methods when they want a longer-lasting effect on the brain. If scientists wanted to study a region deep within the brain that light can’t reach, they would need to use a
different technique. 

Nonetheless, as Zemelman pointed out, optogenetics is another tool scientists can use to unravel the enigmas intertwined in the circuitry of the brain.  

“We want to know specific stuff about cells in the brain while it’s intact, and light happens to be a convenient way to do that … but light is not the big story,” Zemelman said. “The big story is the brain.”

For more information on optogenetics, check out this TED Talk from Gero Miesenboeck, Zemelman’s partner in developing the basis of optogenetics.