Using the new technology, researchers have made surprising discoveries about how the brain responds to taste

Taste is important to fruit flies as it is to humans: like humans, fruit flies tend to seek out and consume sweet foods and reject bitter foods

In a new study published in Contemporary Biology, researchers at Brown University describe how they developed a new imaging technique and used it to map the neural activity

Study author Nathaniel Snell said: "These results suggest that the way the fruit fly brain encodes food taste is more complex

Gilad Barnea, professor of neuroscience at Brown University's Warren Alpert School of Medicine and director of the Center for Cell and Circuit Neurobiology at the Carney Institute for Brain Science, said that just as important as the researchers' findings are the methods

To learn more about the brain processes that control the taste response of Drosophila, a group of graduate and undergraduate students in the laboratories of Barnear, Snell, and Barneya developed a new imaging technique called "trans-Tango (activity).

The brain responds to stimuli like a relay, Banya explains: "sticks" are passed from one neuron to the next, then to the next, and so on

"Trans-Tango (activity) allows us to selectively observe secondary neurons in the loop so that we can focus on their response to sweet and bitter tastes

Because the responses to sweet and bitter tastes are so different, he said, the researchers' expectation is that neural activity along the neural circuits that regulate these responses will also be completely different

Some findings may show how flies know how to avoid specific rotten, poisonous, or otherwise bad parts of

"You have to remember that whether you're a fly or a human, eating is an activity that can't be wrong," he says

There was one discovery that particularly interested Baneja, not because of what it said about survival, but because of what it revealed about potential pleasure

This, Barnea says, reminds him of the concept of "aponia," which in ancient Greek means "without pain," which the Epicurean philosophers considered to be the highest state of

"The fact that we see neurons responding to both the removal of 'bad' stimuli (bitterness) and the presentation of 'good' stimuli (sweetness) is biologically reminiscent of this philosophical concept

As for why insects' sense of taste is important to humans, because humans may have different taste experiences, Barnea mentioned that insects find humans particularly attractive: "For example, understanding what drives mosquitoes' taste and smell behavior is very important for learning how to reduce their impact on humans," he said

This study shows how a research question can power the development of a new science and technology that can be used to answer new research questions — and vice versa

"We believe that trans-Tango (activity) can not only be a useful tool for studying how taste works, but also help understand neural circuits

Barnea has spent more than 20 years developing trans-Tango so that it can be successfully applied to fruit flies, he says, yet the team has only spent 5 years developing and publishing trans-Tango (activities) – and is currently working on more adaptation work
.

"The more we use this technology, the better it is, and the more we can learn from it, the more problems we can solve, the more
problems we can apply it to solve," Barneya said.

The study was supported by grants
from the National Institutes of Health (R01DC017146, R01MH105368) and the National Science Foundation of the United States (DGE1058262).

Article title

Complex representation of taste quality by second-order gustatory neurons in Drosophila