This colorful web is the most complete look yet at a fruit fly’s brain cells

Scientists compiled 21 million images of the noggin of Drosophila melanogaster

fruit fly brain map

BRAINBOW  Scientists have imaged the fruit fly brain in new detail. Colors highlight the paths of nerve cells that have been mapped so far. 

Full Adult Fly Tracing Community, Philipp Schlegel/Drosophila Connectomics Group/Univ. of Cambridge

If the secret to getting the perfect photo is taking a lot of shots, then one lucky fruit fly is the subject of a masterpiece.

Using high-speed electron microscopy, scientists took 21 million nanoscale-resolution images of the brain of Drosophila melanogaster to capture every one of the 100,000 nerve cells that it contains. It’s the first time the entire fruit fly brain has been imaged in this much detail, researchers report online July 19 in Cell.

Experimental neurobiologists can now use the rich dataset as a road map to figure out which neurons talk to each other in the fly’s brain, says study coauthor Davi Bock, a neurobiologist at Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Va.

The rainbow image shown at top and in the video below captures the progress on that mapping so far. Despite the complex tangle of neural connections pictured, the mapping is far from complete, Bock says. Neurons with cell bodies close to each other are colored the same hue, to demonstrate how neurons born in the same place in the poppy seed–sized brain tend to send their spidery tendrils out in the same direction, too.

The dataset is already enabling new discoveries about the fruit fly brain. For instance, Bock and colleagues are interested in the neurons that help flies make memories. He and his team traced neurons that send messages to and from a structure in the fly’s brain called the mushroom body, which is involved in learning and memory. In the process, the researchers discovered a new type of neuron that talks to cells in the mushroom body. The brain has two such neurons, one on each side, Bock says. Each has a broad crown of dendrites that receive signals from neurons in many different places in the brain. Because of their far-reaching influence, the cells might be involved in integrating different kinds of sensory information, he suggests.

FULL SPECTRUM A three-dimensional view of the neurons in the fruit fly brain that have been traced so far highlights the complexity in this relatively simple brain.

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