IBM's BlueGene L supercomputer has helped researchers in the United States simulate a mouse-like brain. Researchers utilized BlueGene while they ran a "cortical simulator" that reportedly was "as big and as complex as half of a mouse brain." Scientists believe that a half of a mouse brain actively contains around eight million neurons, with each one possibly having up to 8,000 synapses communicating with one another.
James Frye, Dharmendra Modha and Rajagopal Ananthanarayanan detailed how they simulated a mouse brain in a researcher paper: "Towards Real-Time, Mouse-Scale Cortical Simulations."
Researchers Simulate Mouse Brain on Computer