The promise of whole-brain connectomics

In recent years, new tools have emerged for circuit reconstructions in mammalian brains. For local circuits, large-scale electron-microscopic reconstructions (EM connectomics) can now map synaptic connectivity in networks up to tens of thousands of neurons. So far, long-distance axonal projections in mammals can only be reconstructed sparsely, with targeted injections of tracers, so mapping individual axons has never been achieved in humans. Reid will describe our new program to create a densely sampled map of axonal projections, with the long-term goal of reconstructing the trajectories of many/most large projection axons (>1 um diameter) to create an axonal connectome of the human brain.