Scientists have made a breakthrough in understanding how the brain works in relation to the rest of the central nervous system.
Researchers at the Howard Hughes Medical Institute in Virginia found a way to capture the activity in an entire, non-transparent central nervous system in real time.
They tested the technique for the first time on larvae of Drosophila, a fruit fly—sometimes called a "wine" fly in reference to its characteristic behaviour of lingering around rotting or overripe fruit. The research is published in a new paper in Nature Communications.
This video shows neurons firing through the fruit fly larva as it crawls forward and backward. The images were taken five times a second for up to an hour, at state-of-the-art high resolution.
The researchers captured the video using a light-sheet microscope capable of simultaneous multi-view imaging at a record speed, and a high-tech computer system to analyse it and turn it into 3D imaging.
"It is becoming increasingly clear that to understand how neuronal networks function, it is important to measure neuronal network activity at the system level," the paper concludes. "Our method enables, for the first time, the imaging of activity within the entire Central Nervous System."
The larvae were genetically modified in preparation to make their neurons fluoresce when they fire, so they would be visible. This enabled the scientists to connect neurons in the brain with the corresponding motor programs they trigger in the ventral nerve cord—in other words, the commands which control the muscles in the nervous system. A method like this makes it possible to study how the brain and nerves work simultaneously to generate behavior.
Philipp Keller, one of the main scientists involved in the study, told the Guardian: "We are curious to see neural activity as behaviours are being produced. By imaging different parts of the nervous system at the same time, we can see how behaviours are controlled and then build models of how it all works."
This method has opened the door to the possibility of future analysis in larger organisms; the scientists hope to move on next to testing it on zebrafish and mouse embryos.