FlyEM

FlyEM is a neuroscience project based at the Howard Hughes Medical Institute’s Janelia Research Campus that aims to map the synaptic wiring diagram of the Drosophila melanogaster brain using high-resolution electron microscopy. The project combines advanced imaging with manual and automated neuron tracing to produce connectomic reconstructions that specify which neurons connect and where synapses occur, providing a structural blueprint of neural circuits. Its work is intended to advance understanding of how neural circuits generate behavior and to support methodological developments in connectomics.

Key outputs from FlyEM include large EM datasets and annotated reconstructions. The FAFB dataset, short for Full Adult Fly Brain, offers a nearly complete volumetric image of a fly brain, while the hemibrain dataset provides a densely annotated connectome derived from roughly half of an adult brain. These resources are publicly accessible and are widely used by researchers to explore neuronal circuits, test hypotheses, and compare structural motifs across datasets. The data are explored and annotated using CATMAID, a web-based platform designed for collaborative neuron tracing and synapse annotation, and associated tools developed by the FlyEM team.

The FlyEM initiative has contributed to advancing community resources for connectomics, enabling researchers to study circuits involved in olfaction, vision, and behavior in Drosophila. By releasing datasets, reconstruction annotations, and analysis tools, FlyEM supports reproducibility and cross-laboratory collaboration in neuroscience. The project emphasizes open data practices and ongoing development of scalable workflows for neuronal circuit mapping.