Like humans, fruit flies like to eat sweet foods and reject bitter ones. It's not known how sweet and bitter tastes are represented by the brain circuits.
The researchers at Brown University used a new technique to map the neural activity of fruit flies in response to sweet and bitter tastes.
Nathaniel Snell, who earned his PhD in neuroscience from Brown in 2021, conducted the research as part of his thesis.
A professor of neuroscience at Brown's Warren Alpert Medical School and director of the Center for the Neurobiology of Cells and Circuits at the University's Carney Institute for Brain Science said that the method they used was just as important as the findings.
A group of graduate and undergraduate students in Barnea's lab developed a new technique to study the brain processes that govern the flies' reaction to taste sensations. The technology used to trace neural circuits in the brain is called trans-Tango. According to Barnea, trans-Tango reveals how specific neurons in the circuits respond to stimuli.
The brain responds to stimuli like a relay, with the "stick" moving from one neuron to the next. The person who gave the stick to the neuron wasn't identified by previous techniques.
The ability to look at the second-order neurons in the circuit allowed us to focus on how they respond to sweet and bitter tastes.
The researchers expected that the neural activity along the circuits that make up the reactions to sweet and bitter would be completely different. In response to the two tastes, there was overlap of neural activity in the second-order circuits.
Some of the results could show how flies know to avoid bad parts of a food. He said that the study findings underscore the importance of taste.
He said that even though you are a fly or a human, you cannot make mistakes. It can be bad to consume something that is bad for you. People can confirm this if they have ever eaten a bad mussel. The survival of the species depends on the ability to avoid certain foods.
One finding was particularly interesting to Barnea, not because of what it said about survival, but what it could reveal about pleasure. When the tastes were removed, the second-order neuron responded to bitter tastes as well. Barnea and his colleagues found an overlap in activity when the bitter and sweet were present.
The concept of "aponia," which in ancient Greek means "the absence of pain," was thought to be the height of pleasure.
According to Barnea, the fact that we see a neuron that responds to both the bad and good stimuli is biologically similar to the idea of a good and bad taste.
Understanding what drives gustatory and olfactory behaviors in mosquitoes is very important in learning how to decrease their effect on humans. One small piece may be added to the large puzzle.
The study shows how a research question can help spur the development of a new scientific technique that can be used to answer new research questions.
The sense of taste can be studied using trans-Tango, but it can also be used to understand neural circuits in other areas. Neuroscience is concerned with figuring out howSensory neurons communicate with each other as they travel from peripheral to deeper layers of a neural circuit. It is certain that Trans-Tango will be able to answer these questions.
He said it took Barnea more than 20 years to develop trans-Tango to the point where it could be used successfully in fruit flies, but only five years for the team to develop and publish trans-Tango.
The more we use technology, the better it gets, and the more we can learn from it.
More information: Nathaniel J. Snell et al, Complex representation of taste quality by second-order gustatory neurons in Drosophila, Current Biology (2022). DOI: 10.1016/j.cub.2022.07.048 Journal information: Current Biology
All Rights Reserved © 2024
