Zheng, Z. et al. Cell 174, 730–743 (2018).
Whole-brain electron microscopy (EM) datasets are available for a few select organisms and have proven invaluable for researchers attempting to gain a better understanding of the neuronal circuitry. Zheng et al. report an EM dataset of an adult female Drosophila brain at synaptic resolution. The team cut about 7,000 serial sections, imaged them with transmission EM and assembled them into a high-quality volume reconstruction. For efficient imaging, the researchers used either transmission EM camera arrays or an automated sample-loading system in combination with a regular transmission EM system. To ascertain the quality of the acquired data, they manually traced neurons in the mushroom body, an olfactory memory center in the fly brain, and found that the reproducibility between independent tracings of the same neurons was high. Furthermore, the traced neurons could be aligned to neurons reconstructed on the basis of light microscopy images. The whole-brain dataset is freely available for use in further studies.