Neuron Pair in Flies Guides Life-or-Death Choices

Researchers identify neurons that integrate sweet and bitter signals to help flies decide what to eat

Mar. 19, 2026 at 12:54am

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Researchers at Brown University's Carney Institute for Brain Science have identified a pair of neurons in fruit flies that integrate sweet and bitter taste signals to help the insects decide whether to eat something or avoid it. The neurons, called subesophageal LK (SELK), receive stronger signals from bitter-sensing neurons and weaker signals from sweet-sensing neurons. The SELK neurons then use different chemical messengers to either direct the fly to eat (if the substance is sweet) or stop feeding (if it is bitter), a critical decision-making process that can mean the difference between life and death for the fly.

Why it matters

This discovery provides new insights into how flies navigate the complex decision of what to eat, a process that is essential for their survival. The finding that a single neuron can integrate multiple sensory inputs and make this life-or-death choice is an impressive example of the computational power of the brain. The researchers say this decision-making mechanism may be conserved across species, including humans, which could make these neurons attractive targets for future pharmaceutical interventions.

The details

The researchers, led by Brown professor Gilad Barnea, found that the SELK neurons receive stronger signals from bitter-sensing neural populations and weaker signals from sweet-sensing populations. The SELK neuron then uses different chemical messengers to either direct the fly to eat (by releasing a neurotransmitter) if the substance is sweet, or stop feeding (by secreting a neuropeptide) if it is bitter. This allows the fly to instantly evaluate whether a food source is safe or potentially toxic based on taste.

  • The study was published online in Nature Communications in 2026.

The players

Gilad Barnea

A professor of neuroscience and director of the Center for the Neurobiology of Cells and Circuits at Brown University's Carney Institute for Brain Science.

Doruk Savaş

The lead study author who earned his Ph.D. from Brown and is now a researcher at Harvard University.

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What they’re saying

“If a fly makes just one mistake about what to eat, it may die. So the decision is super important. This newly discovered mechanism illustrates the impressive level of computation that a single neuron can do.”

— Gilad Barnea, Professor of neuroscience and director of the Center for the Neurobiology of Cells and Circuits at Brown's Carney Institute for Brain Science

“The mainstream understanding in the field was that sweet-sensing neural populations only 'talk' to a certain subset of neurons, and bitter-sensing populations only talk to a different subset, and there's really no interplay between them. But what I was seeing was that there's a neuron that is 'listening' to both.”

— Doruk Savaş, Lead study author and researcher at Harvard University

What’s next

Recent work has reported a similar finding in the mouse brain, suggesting this decision-making mechanism may be conserved across species. If identified in humans, these neurons could become attractive targets for future pharmaceutical interventions.

The takeaway

This discovery provides new insights into the impressive computational power of a single neuron, which can integrate multiple sensory inputs to make a critical life-or-death decision for the fruit fly. The finding that this decision-making mechanism may be conserved across species raises the possibility of translating these insights to human health and disease.