In addition to LADY GAGA, Samuel and his team relied on another oddly named piece of technology to unlock navigational behavior, the MAGAT analyzer. “The problem with earlier experiments is that when you put a scent on one side of the plate, you can’t keep it there,” said Marc Gershow, a postdoctoral fellow in physics and designer of the device. As long as it is renewed by the injector, the scent effectively stays put. Unlike similar experiments, which typically used a droplet of an odor-producing chemical, the breeze prevents the odor from diffusing throughout the device. At one end, Samuel said, the scent is absent, while it is unavoidable at the other. Using a computer program to control precisely when, where, and how much scent is injected enables the device to produce a perfectly linear gradient of odor across the plate. “It works by pushing air across a plate to create a very slight breeze - approximately one centimeter per second - while a series of switches injects scents into the airflow.” “This was the most challenging stimulus-control system we’ve ever built,” Samuel said of the device. And once that navigational decision starts, we know how it’s carried out.”Īt the heart of the work was an unusual piece of technology, the Linear and Dynamic Gaseous Gradient Apparatus - or LADY GAGA for short - that allowed researchers to precisely control odors in the air. We know smells cause the animal to initiate a navigational decision. “We now believe we have a complete algorithmic picture of how those decisions are made, based on the ways in which motor activity is regulated by these inputs. “What we have shown is that the larvae really make left- and right-steering decisions based on sensory input,” said Aravinthan Samuel, professor of physics and co-author of the paper. A team of Harvard researchers, however, is rewriting that assumption with research showing that the lowly fruit fly maggot is capable of making the same choices.Īs described in a recent paper in the journal Nature Methods, the research is aimed at answering one of the most fundamental, long-standing questions about how the brain gives rise to behaviors. For decades, scientists have associated binary decision making - opting to go left or right - with higher-ranking animals, including humans.
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