A Complete Electron Microscopy Volume of the Brain of Adult Drosophila melanogaster

TLDR

Drosophila melanogaster possesses a 100,000‑neuron brain with diverse behaviors, and only electron microscopy can fully map its synaptic connectivity, yet its size exceeds conventional EM capabilities. The study aimed to develop a high‑throughput EM platform to image the entire adult female fly brain at synaptic resolution. The platform was validated by tracing mushroom‑body circuitry spanning the brain, a well‑studied learning center. All inputs to Kenyon cells were mapped, uncovering a novel postsynaptic partner cell type, unexpected clustering of olfactory projection neurons, and demonstrating that the freely available EM volume enables brain‑spanning circuit mapping to accelerate Drosophila neuroscience. A video abstract accompanies the dataset.

Abstract

Drosophila melanogaster has a rich repertoire of innate and learned behaviors. Its 100,000-neuron brain is a large but tractable target for comprehensive neural circuit mapping. Only electron microscopy (EM) enables complete, unbiased mapping of synaptic connectivity; however, the fly brain is too large for conventional EM. We developed a custom high-throughput EM platform and imaged the entire brain of an adult female fly at synaptic resolution. To validate the dataset, we traced brain-spanning circuitry involving the mushroom body (MB), which has been extensively studied for its role in learning. All inputs to Kenyon cells (KCs), the intrinsic neurons of the MB, were mapped, revealing a previously unknown cell type, postsynaptic partners of KC dendrites, and unexpected clustering of olfactory projection neurons. These reconstructions show that this freely available EM volume supports mapping of brain-spanning circuits, which will significantly accelerate Drosophila neuroscience. VIDEO ABSTRACT.