connectome
A complete wiring diagram of a nervous system, showing every neuron and every connection between them.
A connectome is a map of what is wired to what inside a brain. Building one means slicing the brain into sections far thinner than a hair, photographing each one with an electron microscope, and then tracing every single nerve cell through thousands of images to see where it goes. The field that does this is called connectomics, and it is where a lot of AI quietly does useful work: models trained to follow the outline of one cell across a stack of photographs handle the first pass, because no team of humans could trace a hundred million connections by hand.
It is worth knowing what a connectome does not tell you. It shows the wiring, not the traffic. How strongly each connection fires, which chemicals are involved, and how any of it shifts while the animal learns are all separate questions. A connectome is the map, not the journey.