Scientists at the University of Geneva have identified a specific neural circuit in fruit flies that links the internal biological clock to brain regions regulating wakefulness. As reported on October 1, 2026 in the journal Current Biology, clock neurons inhibit dopamine-producing cells to control daily activity rhythms.
How do biological clock neurons connect to wakefulness circuits in the brain?
Sleep and wakefulness are partly controlled by an internal biological system known as the circadian clock, which generates rhythms of approximately 24 hours. While researchers have long understood that this network regulates sleep-wake cycles, body temperature, and hormone production, the exact mechanisms allowing the clock to act on brain circuits remained poorly understood.
To investigate these connections, Emi Nagoshi’s laboratory at the Section of Biology of the UNIGE Faculty of Science used the fruit fly, Drosophila melanogaster. Using genetic mapping of connections between neurons, the scientists identified the nerve cells located downstream of the biological clock neurons.
What role does dopamine play in daily sleep-wake cycles?
Imaging techniques that measure neuronal activity showed that cellular activity varies throughout the day. Researchers identified a connection between the biological clock neurons and a population of neurons that produce dopamine, a key molecule that enables neurons to communicate with one another.
“We observed that the clock neurons inhibit these dopaminergic neurons, which in turn stimulate neurons in the mushroom body,” explained Blanca Lago Solis and Rafael Koch, postdoctoral researcher and research associate in Emi Nagoshi’s group. The mushroom body plays a role in learning, memory, and the regulation of sleep, contributing to wakefulness during the day.
When the clock neurons inhibit the dopaminergic neurons, the wake-promoting signal decreases. Conversely, releasing this inhibition allows the dopaminergic neurons to stimulate the mushroom body more strongly, promoting wakefulness.
Why are these circadian findings important for understanding sleep disorders?
Disruptions of the circadian clock are associated with various sleep disorders and alterations in brain function. A better understanding of these fundamental neural mechanisms could ultimately help explain how disturbances in biological rhythms affect the brain.
The study, titled “Circadian control of dopaminergic signaling to the mushroom body regulates sleep through rhythmic Pka-C1 transcription in Drosophila,” provides foundational data on how internal biological timing translates into physical neuronal activity.
What are the most common questions about this biological clock research?
- Which organism was used for this circadian clock study?
- Researchers used the fruit fly, Drosophila melanogaster, to map the neural connections between the biological clock and wake-promoting brain regions.
- Where was the study published?
- The findings were published on October 1, 2026, in the scientific journal Current Biology under DOI: 10.1016/j.cub.2026.09.014.
- Which research team conducted the investigation?
- The research was led by Associate Professor Emi Nagoshi’s laboratory at the Department of Genetics and Evolution within the Section of Biology at the UNIGE Faculty of Science.
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