A team at Washington University in St. Louis developed a computational method called MITE (Mutual Information and Transfer Entropy) to reveal how cells in the suprachiasmatic nucleus (SCN) communicate. The work, led by Professor Erik Herzog and research scientist KL Nikhil and published in the Proceedings of the National Academy of Sciences, involved an interdisciplinary team including Daniel Granados-Fuentes, Jr-Shin Li, Bharat Singhal and István Kiss.
Using weeks-long recordings of gene expression with cellular resolution, the researchers reconstructed more than 25 million connections among over 8,000 cells across 17 mice with over 95% accuracy. Although the mouse SCN contains around 20,000 neurons, the maps indicate that only a small subset of highly connected hub cells is essential for synchrony.
The team identified five functional cell types. Among them are highly connected hub cells, including a small subset of VIP-expressing neurons that broadcast synchrony signals; bridge cells that relay signals from hubs to other parts of the network; and sink cells that receive converging signals and likely send timing information to the rest of the body. Computational models showed that removing only the hub neurons made network synchrony collapse, supporting the critical role of hubs. Next steps include pinpointing how hub cells exert influence and whether targeted interventions could tune SCN timing to help shift workers and people with seasonal affective disorder.
Difficult words
- computational — using computers and algorithms to study data
- reconstruct — to build a model of something from datareconstructed
- synchrony — happening at the same time together
- hub — a central cell with many connectionshub cells, hub neurons, hubs
- broadcast — to send a signal to many receivers
- relay — to pass a signal from one place
- converge — to come together in one place or sourceconverging
- intervention — an action intended to change a resultinterventions
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Discussion questions
- How could tuning SCN timing help shift workers or people with seasonal affective disorder?
- If scientists could change hub cells, would you try a treatment to shift your sleep schedule? Why or why not?
- Why is it important that only a small subset of cells is essential for synchrony?
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