Applying functional MRI analysis techniques to whole-brain calcium-imaging data to investigate structural and functional relationships in Drosophila melanogaster

Abstract

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.

Abstract of "Applying functional MRI analysis techniques to whole-brain calcium-imaging data to investigate structural and functional relationships in Drosophila melanogaster" by Takuto Okuno, Alexander Woodward, Hideyuki Okano et al., https://doi.org/10.1101/2025.07.01.662601, used under its Creative Commons Attribution license (CC-BY); markup removed, otherwise unmodified.