What it is
The MICrONS consortium recorded calcium activity from about 75,000 neurons across four visual areas in an awake mouse, then co-registered that functional data with an electron-microscopy reconstruction of the same tissue containing more than 200,000 cells and roughly 0.5 billion synapses. The reconstruction spans about one cubic millimeter of cortex and traces dendrites and long-range axons to thousands of cell-to-cell connections per neuron. It is released as an open resource with retrieval and analysis tools.
Why it matters
Connectomics has mapped wiring, and physiology has measured activity, but rarely in the same tissue at scale. Linking the responses of 75,000 neurons to their actual synaptic connections lets researchers ask how circuit architecture produces computation, and it anchored the body of work that made EM connectomics Nature's Method of the Year for 2025.
Underlined numbers link to their source. Every metric and quoted figure is listed under Sources and data below.
Filed underconnectomics, neuroscience, visual-cortex, open-data, mouse