The connectome of olfactory memory circuits in the adult fly

A team of researchers is reconstructing every single synaptic connection in the memory circuits of an adult female fruit fly brain, using a 106-terabyte electron microscopy dataset—100 times larger than any whole-brain volume previously imaged. This matters because connectomics—mapping complete neural wiring diagrams at the level of individual synapses—remains in its infancy. Most neuroscientists believe it will eventually transform the field, but concrete, large-scale demonstrations are still rare. The fruit fly’s olfactory memory centre, the mushroom body, operates on logical principles—sparse coding, dopamine-dependent plasticity, and valence segregation by neuronal population—that are directly relevant to mammalian brains. Yet no complete wiring diagram of such a memory centre currently exists. If successful, this project will produce the first complete network and synaptic organisation of a memory centre within four years. This will enable over 200 Drosophila laboratories to run targeted experimental circuit studies, and will pilot the methods needed for large-scale, geographically distributed connectomics. The work is fundamental science: it does not aim at an immediate practical application. But past fundamental mapping efforts—such as the C. elegans connectome—have underpinned decades of discoveries about neural computation, learning, and disease mechanisms. A complete fly memory circuit could similarly accelerate understanding of how brains store and retrieve information.