Nav: Home

Virtual reality takes a leap into taste

June 21, 2019

The fly hasn't eaten for an entire day and it's starving. Finally, it finds a pile of edible gelatinous goo. It begins eating when suddenly a green light appears, and the food, which was far from delicious a moment ago, becomes irresistibly sweet. The fly, excited by the sudden improvement, eats with increased vigor. But its enthusiasm quickly wanes when the green light disappears and the flavour of the food reverts to its original blandness.

Reflecting on such an unusual situation, one might guess that it was the result of an added sweetener, or some sort of temporary delusion. But no, the answer lies within the realm of what might have been considered until recently to be science fiction.

"The fly's experience was very real. It was a virtual taste created by directly manipulating its taste neurons", says Carlos Ribeiro, head of the behavior and Metabolism lab at the Champalimaud Centre for the Unknown in Lisbon, Portugal. Together with his team, Ribeiro developed the optoPAD: a system that creates "virtual taste realities", in a way that can be flexibly paired with the fly's behavior. They describe this new technology in a scientific article published today June 21st in the journal eLife.

Creating virtual taste realities

The optoPAD combines two high-tech elements: the first is optogenetics, a powerful method that uses light to control the activity of neurons (quite literally to turn them "on" or "off"). For instance, the fly mentioned earlier was briefly enjoying more appetizing food because its sweet-sensing neurons were optogenetically activated by exposure to green light.

The second element of the optoPAD is an additional system, previously developed in the lab, called flyPAD. "The flyPAD uses touchscreen-type technology to monitor the fly's feeding behavior. Just like your phone is able to detect the touch of your finger on the screen, flyPAD is able to detect whenever the fly touches the food", explains José-Maria Moreira, one of the leading co-authors of study.

By combining flyPAD with optogenetics, the researchers were able to overcome one of the main challenges in the field of feeding research: precisely controlling taste sensations.

Unlike auditory or visual information, which can be altered instantaneously and independently of the animal's behavior, animals only experience taste information when they voluntarily touch the food with their tongue, or proboscis (in the case of the fly). "With optoPAD, we are constantly monitoring the behavior of the fly, to ensure that we optogenetically change the taste of the food precisely when the fly is in contact with it", Moreira explains.

Taste and beyond

In this study, which shows that the optoPAD is able to effectively pair active feeding with optogenetic manipulations, the researchers demonstrate that these virtual tastes have a very real effect on the behavior of the flies.

For instance, they are able to make the fly eat excessively by optogenetically activating sweet-sensing neurons; or make the fly stop eating all together, regardless of how hungry it is, by optogenetically activating bitter-sensing neurons.

For the researchers, manipulating taste was a good beginning, but it wasn't enough. "We developed the optoPAD, because we are interested in understanding how the brain makes one of the most fundamental decisions for our health: what food to eat", says Dennis Goldschmidt, another leading co-author, "but food choices do not only depend on taste, many parts of the brain are involved, so we wanted to ensure that optoPAD can be used to study the activity of neurons anywhere".

Since taste neurons are located in the mouth of the fly, which makes them easily accessible to the light needed for manipulation, the team chose a more difficult target: neurons at the center of the brain that are involved in jumping reactions.

The results were clear: "as we expected, optogenetic stimulation of these 'jumping' neurons, made the flies jump and stop feeding, showing that indeed, we can study any neuron, regardless of its location, in order to understand its role in the brain's feeding circuitry", says Goldschmidt.

Next steps

Though optoPAD seems like a fantastic way to improve one's nutrition without compromising taste, the researchers' goal is to use this technology to improve human life in a more fundamental way. "The food we eat affects all aspects of our lives, including aging, ability to reproduce, lifespan, mental state and mood", says Ribeiro. "Yet, how the brain controls food choice is still a mystery. The optoPAD can help us identify the neurons and genes that may have a direct impact on nutrition and hence our well-being in years to come."

The team is now gearing up to start a series of new experiments, and they are already freely sharing this exciting new technology with the scientific community by making all the blueprints and software freely available here: http://ribeirolab.org/optopad/. "We expect that the flexibility of the optoPAD will allow researchers not only to study feeding behavior but to also explore how flies adapt their behavior to complex environmental features, which will in turn may lead to the identification of novel neuronal circuits and computations", Ribeiro concludes.
-end-
Original article reference: José-Maria Moreira*, Pavel M. Itskov*, Dennis Goldschmidt*, Célia Baltazar, Kathrin Steck, Ibrahim Tastekin, Samuel J. Walker, Carlos Ribeiro. (2019). optoPAD, a closed-loop optogenetics system to study the circuit basis of feeding behaviors. eLife. https://doi.org/10.7554/eLife.43924

Champalimaud Centre for the Unknown

Related Neurons Articles:

Paying attention to the neurons behind our alertness
The neurons of layer 6 - the deepest layer of the cortex - were examined by researchers from the Okinawa Institute of Science and Technology Graduate University to uncover how they react to sensory stimulation in different behavioral states.
Trying to listen to the signal from neurons
Toyohashi University of Technology has developed a coaxial cable-inspired needle-electrode.
A mechanical way to stimulate neurons
Magnetic nanodiscs can be activated by an external magnetic field, providing a research tool for studying neural responses.
Extraordinary regeneration of neurons in zebrafish
Biologists from the University of Bayreuth have discovered a uniquely rapid form of regeneration in injured neurons and their function in the central nervous system of zebrafish.
Dopamine neurons mull over your options
Researchers at the University of Tsukuba have found that dopamine neurons in the brain can represent the decision-making process when making economic choices.
Neurons thrive even when malnourished
When animal, insect or human embryos grow in a malnourished environment, their developing nervous systems get first pick of any available nutrients so that new neurons can be made.
The first 3D map of the heart's neurons
An interdisciplinary research team establishes a new technological pipeline to build a 3D map of the neurons in the heart, revealing foundational insight into their role in heart attacks and other cardiac conditions.
Mapping the neurons of the rat heart in 3D
A team of researchers has developed a virtual 3D heart, digitally showcasing the heart's unique network of neurons for the first time.
How to put neurons into cages
Football-shaped microscale cages have been created using special laser technologies.
A molecule that directs neurons
A research team coordinated by the University of Trento studied a mass of brain cells, the habenula, linked to disorders like autism, schizophrenia and depression.
More Neurons News and Neurons Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: IRL Online
Original broadcast date: March 20, 2020. Our online lives are now entirely interwoven with our real lives. But the laws that govern real life don't apply online. This hour, TED speakers explore rules to navigate this vast virtual space.
Now Playing: Science for the People

#573 Penis. That's It. That's the title.
This episode is about penises. That was your content warning. Penises. Where they came from. Why they're useful. And the many, many wild things that animals do with them. Come for the world's oldest penis, stay for the creature that ejaculates 80 percent of its bodyweight. Host Bethany Brookshire talks with Emily Willingham about her new book, "Phallacy: Life Lessons from the Animal Penis".
Now Playing: Radiolab

Falling
There are so many ways to fall–in love, asleep, even flat on your face. This hour, Radiolab dives into stories of great falls.  We jump into a black hole, take a trip over Niagara Falls, upend some myths about falling cats, and plunge into our favorite songs about falling. Support Radiolab by becoming a member today at Radiolab.org/donate.