To create the simulation, researchers did thousands of experiments on rat brains over a 20 year period, logging each type of synapse and neuron discovered. That led to a set of fundamental rules describing how neurons connect to synapses and form microcircuits. Using the data, they developed an algorithm to pinpoint the synapse locations, simulating the circuitry of a rat's brain. All of that data was then run through a supercomputer: "It was only with this kind of infrastructure that we could solve the billions of equations needed," said software lead Felix Schurmann.

One of the biggest discoveries was the role of calcium in the brain. Early simulation tests resulted in "synchronous" neural activity, usually found in the brains of sleeping animals. "When we (digitally) decreased the calcium levels to match those found in awake animals, the circuit behaved asynchronously, like neural circuits in awake animals," according to lead author Eilif Muller. They concluded that chemical changes and others mechanisms can shift a brain circuit from one state to another, which could help doctors treat patients with abnormal brain activity.

The research will provide immediate data for any other scientists who work with the brain. However, the team stressed that "the reconstruction is a first draft... and it is not yet a perfect digital replica of the biological tissue." In other words, further tweaks to the model will yield even more discoveries in the areas of brain function, neurological disorders and, yes, artificial intelligence.