A friend who is a doctor was talking about the limited usefulness of doing brain scans to determine "what part of the brain does X".
One of his points was that neurons work (mostly) by "exciting" or "inhibiting" other neurons. When you see, on a scan, that part of the brain is "working," you don't actually know whether the area's neurons are firing more excitation signals or more inhibition signals.
It's too bad we lack a schematic
for brains that are acting erratic.