Let There Be Light! Bioluminescence Breakthrough in Shrimp Can Track Brain Activity

Vanderbilt scientists have developed a probe that causes brain cells to glow in the dark. The key ingredient in this research? A bioluminescent species of shrimp.

Carl Johnson, Stevenson professor of Biological Sciences, spearheaded the research that was published in the journal Nature Communications on October 27, 2016. "For a long time, neuroscientists relied on electrical techniques for recording the activity of neurons," Johnson stated. "These are very good at monitoring individual neurons but are limited to small numbers of neurons. The new wave is to use optical techniques to record the activity of hundreds of neurons at the same time."

Johnson and his team theorized that combining luminescence with optogenetics, a new biological technique that uses light to control cells in living tissue, would result in a revolutionary tool to monitor brain activity. The sensor is a genetically modified form of luciferase from the selected shrimp species. It's the same enzyme that other organisms use to generate light. Utilizing cultured neurons, the researchers found that the luminescent shrimp luciferase reacted visibly when exposed to calcium ions, glowing in the dark when stimulated by brief flashes of visible light.

Fluorescence, which was used in optical recording, heats up living tissue and disrupts certain biological processes. "There is an inherent conflict between fluorescent techniques and optogenetics. The light required to produce the fluorescence interferes with the light required to control the cells," enthused Johnson. "Luminescence, on the other hand, works in the dark!"

"We've shown that the approach works," Johnson said. "Now we have to determine how sensitive it is. We have some indications that it is sensitive enough to detect the firing of individual neurons, but we have to run more tests to determine if it actually has this capability."