A study published June 26, 2026 in PLOS Computational Biology quantifies the anatomy of the brain's three main neuromodulator systems, acetylcholine, dopamine, and serotonin, in the developing rat neocortex, and models how each one shapes the slow electrical rhythms that cortical circuits produce. The work, led by Srikanth Ramaswamy at Newcastle University with the Blue Brain Project at EPFL and collaborators in Madrid, pairs detailed measurements of where these chemical fibers run, and how densely, with a biophysical simulation of the cortex, so the team can ask what happens to network oscillations when each system is turned up or down.
The three systems came out looking distinct rather than interchangeable: they differ in how widely their fibers spread across the cortical layers and in which rhythms they push on, including the slow, delta-band waves that mark deep sleep. That specificity is the point. What we loosely call brain chemistry is not one dial but several, each wired differently and pulling on a different part of the brain's electrical behavior.
The honest caveats are large. This is a model built on the anatomy of a young rat's cortex, not a waking human brain switched between states on command, and a map of which molecule bends which rhythm is a long way from explaining why any rhythm is accompanied by an inner life at all.
We are getting a gorgeous wiring diagram of the knobs that tune the brain's electrical weather, and still not the faintest schematic for why the weather is experienced by anyone.