Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

Flyswatter spotter: A reconstruction of 379 neurons involved in motion detection in the fruit fly.

One of the largest connectomes published to date reveals how brains can detect motion.

Researchers at the Howard Hughes Institute’s Janelia Farm Research campus and their collaborators report in Nature on Wednesday that they were able to reconstruct the shapes and interconnections of neurons within a small part of the fly brain that is responsible for detecting visual motion.

By mapping the brain structure in such detail, the researchers gained new insight into how the brain detects movement. Their work is the latest example of many ongoing efforts in neuroscience to understand how the brain functions by building intricate diagrams of neuronal connections, or connectomes (see “Connectomics”).

A theory for how neurons might work together to interpret motion had been around for about 60 years, but scientists didn’t know how the behavior was carried out by neuronal circuits, says senior author Dmitri Chklovskii. In part, that’s because tracing a neuronal circuit, even in the small brain of a fruit fly, is extremely difficult, he says.

To build their detailed three-dimensional map, Chklovskii and colleagues took pictures of very thin slices carved from a frozen fly brain and then stitched together more than 20,000 of those images. They were able to automate much of this reconstruction, but humans had to go through to check for errors. In total, around 14,400 person-hours were needed to build the connectome of 379 cells with 8,637 synaptic connections.

The researchers identified cells connected to each other in circuits that fit with the existing model for how brains detect motion. But to fully connect the structural information to behavior, patterns of neuron activity need to be combined with these detailed maps. Mapping out neuron activity in the brain is one of the major goals of the large scale neuroscience initiative announced by President Obama earlier this year (see “The Brain Activity Map”)

Along those lines, a more complete story of how the brain computes motion emerged when the wiring diagram was combined with the results of another study published in the same issue of Nature. Using fluorescent molecules that glow when neurons are active, a second team of scientists demonstrated that four subsets of neurons in the motion connectome each respond to motion in one of four cardinal directions: left, right, up, and down.

 “With the combination of our anatomical work with theory, and the physiology and behavioral work of other labs, the whole story is starting to become clear now,” says Chklovskii. The connectomes of fly brains and human brains differ from one another, but “in both cases, the brains have to perform similar computations,” Chklovskii says. “The lessons learned will provide insight into solving how more complex computations are performed in the brains of animals, including vertebrates like us.”

0 comments about this story. Start the discussion »

Credit: Credit: Chklovskii Lab & FlyEM project; Janelia Farm Research Campus

Tagged: Biomedicine

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me