Ever wonder what it would look like inside the brain and nerves of a creature while it does its thing? Scientists did too, and now for the first time they've managed to capture imagery of the entire central nervous system of a living, moving, complex animal.

The team, led by Philipp Keller at Howard Hughes Medical Institute, used a technique called light-sheet microscopy, by which the subject (in this case, the larva of a fruit fly) is illuminated from two sides by lasers while cameras watch. The researchers lit up the larva and captured images while it crawled around, observing the patterns that emerged in the creature's brain cells.

The resulting video shows the signals the larva's central nervous system sends to make its body move. Before now, it was only possible to do this with smaller, simpler organisms, or so slowly that neural activity couldn't be effectively captured.

This whole-brain imaging is the natural next step for the study of how brains work, the researchers suggest.

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"It is becoming increasingly clear that to understand how neuronal networks function, it is important to measure neuronal network activity at the system level," they wrote in the paper, which was published Tuesday in Nature Communications.

The researchers hope that their work will set the stage for similar studies of even larger and more complex brains as the technology matures.