For the first time, neuroscientists illuminated the pathways of an entire central nervous system (CNS)—and it’s all in 3D. Researchers created a video that allows them to visualize firing neurons in an isolated CNS(just the brain and the nerve cord) of larval fruit flies (Drosophila melanogaster), the team reports online today in Nature Communications. The scientists labeled neurons in the larval CNS with a special fluorescent protein to track connections throughout the nervous system when the larva moved. As it inched back and forth, bright oranges and reds cascaded up and down the center of its back, coloring the pathway of neurons that fire to carry out the locomotion. To get the footage, the team used a high-resolution, high-speed form of light microscopy to track neural activity and record the fluorescence from multiple angles, ensuring a complete 3D representation. It then plugged the data into software that compiled them into a fully rounded model on the computer screen—a spinning image that gives scientists a 360° view of how neurons in fruit fly larvae communicate when their bodies move. The fluorescent flashes highlight the connections between specific regions of the CNS, an upgrade in imaging that allows neuroscientists a new insight into the pathways that allow these tiny invertebrates to slink along.
(Video credit: Keller et al./Nature Communications)