Different species may rely on the same neural network formation

Fly brain, mouse brain, worm brain: They all network the same.

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The connections in groups of brain cells (neuronal networks) show a pattern where a few cells are firmly connected while most others have weaker connections. Scientists are trying to understand if this pattern comes from simple mechanisms.

The brain relies on complex network connections among neurons for various functions in all species. Some neurons, however, have much stronger connections with each other compared to the majority of connections, and this pattern is known as “heavy-tailed.” Scientists are curious about how neural networks can reorganize to create these unique, strong connections and whether this process is specific to certain species or governed by a universal principle.

Scientists at the CUNY Graduate Center Initiative for the Theoretical Sciences (ITS), Yale, University of Chicago, and Harvard are getting closer to answering these questions.

The researchers examined extensive datasets of neural connections in fruit flies, mice, and two worm species. They demonstrated how this mechanism could lead to heavy-tailed connections using mathematical models based on Hebbian plasticity—a neuroscience principle stating that neurons that fire together wire together.

Additionally, including neural activity in the model revealed another essential feature: clustering, where neurons tend to form closely connected groups. This study aimed to understand how such heavy-tailed connectivity arises across various species.

Neuro Network Formation Model
(Left) Network of the strongest connections among over 20,000 neurons in the fruit fly brain. (Right) Model of network formation. Some random connections are pruned, while other connections become stronger through a mixture of Hebbian and random growth. Credit: Christopher Lynn

Christopher Lynn, the paper’s first author, a postdoctoral fellow with the ITS program and now an Assistant Professor of Physics at Yale, said“Our model was based on the assumption that neurons rearrange and connect under a mixture of Hebbian and random dynamics. Neurons sometimes connect for specific reasons, but other times randomly.”

“The research team’s model proved applicable across species, showing how simple and general principles of cellular self-organization can lead to the strong connections and tightly connected networks in the brain. The findings suggest that neuronal network formation isn’t dependent on species-specific mechanisms but might be governed by a simple principle of self-organization.”

“This new knowledge could provide an important foundation for investigating brain structure in other animals and may even help to better understand human brain function.”

Journal Reference:

  1. Lynn, C.W., Holmes, C.M. & Palmer, S.E. Heavy-tailed neuronal connectivity arises from Hebbian self-organization. Nat. Phys. (2024). DOI: 10.1038/s41567-023-02332-9

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