New Imaging Technique Captures Brain Activity with Sculpted Light

A new imaging technique may help scientists study the function of the entire nervous system. They've found a way to overcome some of the limitations of light microscopy by capturing brain activity with sculpted light.

Today's neuroscience aims to understand how an organism's nervous system processes sensory input and generates behavior. Yet actually achieving this goal isn't easy. Researchers have to create detailed maps that show how the nerve cells are wired up in the brain in addition to gathering information in real time on how these networks interact.

In fact, researchers traditionally use imaging-techniques that resolve the activity of single cells with high precision. However, these same techniques aren't able to simultaneously look at the function of all neurons that comprise entire brains. There's usually a trade-off between spatial or temporal accuracy and the size of the brain regions that can be studied.

Now, though, researchers have discovered a new method. They used the nematode, C. elegans, in order to better study the nervous system. The new technique essentially "sculpts" the three-dimensional distribution of light in the sample.

"Previously, we would have to scan the focused light by the microscope in all three dimensions," said Robert Prevedel, a quantum physicist, in a news release. "That takes far too long to record the activity of all neurons at the same time. The trick we invented tinkers with the light waves in a way that allows us to generate 'discs' of light in the sample. Therefore, we only have to scan in one dimension to get the information we need. We end up with three-dimensional videos that show the simultaneous activities of a large number of neurons and how they change over time."

The new method involves tagging neurons with a fluorescent protein that lights up when it binds to calcium, signaling the nerve cells' activity. By inserting the calcium sensor into the nuclei rather than the entire cells, the scientists were able to sharpen the image to identify single neurons.

The technique has enormous implications for better understanding how the nervous system functions. In fact, it paves the way for experiments that were not possible before. In the future, the scientists plan to study how the brain processes sensory information to "plan" specific movements and execute them.

The findings are published in the journal Nature Methods.