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bioRxiv · 10.1101/2025.07.01.662601

Functional connectivity, structural connectivity, and inter-individual variability in Drosophila melanogaster

Okuno, T.·Woodward, A.·Okano, H.·Hata, J.
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Abstract

Clarifying the relationship between structure and function is important for understanding the brain. In Drosophila melanogaster, FlyEM and FlyWire electron microscopy-based connectome data and whole-brain calcium imaging data are available. We applied pre-processing methods from fMRI to whole-brain calcium imaging data and comprehensively investigated the optimal parameters. Then, we found that the FC-SC (functional and structural connectivity) correlation decreased linearly with region of interest count, and this trend was the same in flies and humans. We also developed a new, more robust method to quantify the degree of pre-and post-synaptic segregation and investigated this in the fly whole-brain. This revealed that many neurons have unsegregated synapses. We extracted highly unsegregated synapses and compared them with random-extracted null SC matrices. Their FC-SC correlation was significantly higher, indicating that these synapses contribute to FC well. Conversely, highly segregated-synapses showed significantly lower FC-SC correlation and contribute less to FC. Neurons with unsegregated synapses like non-spiking neurons are spread throughout the whole-brain, and they are thought to have a significant influence on FC.

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Okuno, T., Woodward, A., Okano, H., Hata, J.. 2025-07-04. Functional connectivity, structural connectivity, and inter-individual variability in Drosophila melanogaster. https://doi.org/10.1101/2025.07.01.662601

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