Hello,

We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Susan Young Rojahn

A View from Susan Young Rojahn

How a Fly Brain Detects Motion

A detailed neuron-wiring diagram of the fruit fly’s optic lobe helps explain how neurons work together to compute data.

  • August 8, 2013

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

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

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.”

Want to go ad free? No ad blockers needed.

Become an Insider
Already an Insider? Log in.
More from Rewriting Life

Reprogramming our bodies to make us healthier.

Want more award-winning journalism? Subscribe and become an Insider.
  • Insider Plus {! insider.prices.plus !}* Best Value

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus the digital magazine, extensive archive, ad-free web experience, and discounts to partner offerings and MIT Technology Review events.

    See details+

    Print + Digital Magazine (6 bi-monthly issues)

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

    Technology Review PDF magazine archive, including articles, images, and covers dating back to 1899

    10% Discount to MIT Technology Review events and MIT Press

    Ad-free website experience

  • Insider Basic {! insider.prices.basic !}*

    {! insider.display.menuOptionsLabel !}

    Six issues of our award winning print magazine, unlimited online access plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    Print Magazine (6 bi-monthly issues)

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

  • Insider Online Only {! insider.prices.online !}*

    {! insider.display.menuOptionsLabel !}

    Unlimited online access including articles and video, plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

/3
You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.