© GEORGE RETSECK
Understanding how the brain controls behavior is a holy grail for many neuroscientists. Model organisms such as the fruit fly offer a wide array of genetic tools for investigating behavioral questions, but for scientists wishing to do such experiments on a large scale—a discipline called ethomics—there are few technological options.
Drosophila activity monitoring (DAM) systems (from TriKinetics in Massachusetts)—which use one or more infrared light beams to detect the movements of flies in assay chambers—are among the most commonly used ethomic devices. But they lack experimental versatility, and, because the only data they provide are the number of times a fly breaks a light beam, behavioral information is limited.
Systems that use an HD camera mounted above a fly-containing chamber, on the other hand, provide detailed behavioral data, but have typically been costly, says Gerry Rubin of the Howard Hughes Medical Institute’s Janelia Research Campus in Virginia. So using a large number of such devices, as would be necessary for ethomic studies, would be prohibitively expensive.
Taking advantage of recent cost reductions in computer parts, HD cameras, and 3-D printing, Giorgio Gilestro of Imperial College London and colleagues have created affordable and adaptable ethoscopes. They’re so cheap, in fact, that unlike other camera-based systems, they make running many devices at once eminently doable.
Each ethoscope consists of a single circuit board linked to a small HD camera, supported in a 3-D–printed housing above one of eight possible 3-D–printed behavior arenas. The arenas are designed for different behavioral assays, and three optional modules—enabling light stimulation, chamber agitation, or gas infusion—increase the system’s versatility further. For example, Gilestro’s team employs the agitation module to arouse individual insects that have fallen asleep during studies of sleep deprivation in flies.
“Collecting all these different assays and integrating them into an apparatus that you can make by 3-D printing . . . has made the cost of entry [for behavioral scientists] much lower,” says Rubin, who was not involved with the project. “It’s an important contribution to the field.”
The 3-D printing plans, parts list, and software are all free to download at gilestrolab.github.io/ethoscope/. The team even provides plans for Lego or cardboard ethoscopes for educational purposes, but recommends the 3-D–printed version for research. (PLOS Biol, 15: e2003026, 2017)
|ETHOMIC DEVICE||HOW IT WORKS||PRICE||NUMBER OF FILES ASSAYED PER DEVICE||NUMBER OF DEVICES THAT CAN BE USED SIMULTANEOUSLY|
|Fly movement is detected when an insect disturbs an infrared beam.||Approximately $500 to $800||32—each fly in|
an individual glass tube
|Limited mainly by space|
|Ethoscope||An HD camera continuously monitors fly behavior. Using the additional modules, certain fly behaviors (e.g., sleep) can be detected by the computer|
and used to trigger a computer-
controlled stimulus (e.g., shaking
that fly’s chamber).
|Less than $100||Up to 20—either in individual tubes, individual decision-making mazes, or together in social arenas||Limited by space within a|
environment (multiple ethoscopes generate considerable heat
and thus require cooling)