"This is a major breakthrough because it would otherwise take decades, if not centuries, to map the location of each synapse in the brain," said Henry Markram, head of the Blue Brain Project at Switzerland's Ecole Polytechnique Federale de Lausanne.
Launched in 2005, the project aims to develop a virtual mammal brain by 2018.
One of the greatest challenges in neuroscience is to map the synaptic connections between neurons, the statement said, dubbing the so-called "connectome" the "holy grail that will explain how information flows."
To reconstruct a rat's "virtual cortical microcircuit," the researchers used data about the geometrical and electrical properties of neurons compiled over 20 years from experiments on slices of living brain tissue.
"Each neuron in the circuit was reconstructed into a 3D model on a powerful Blue Gene supercomputer," the statement said. "About 10,000 of virtual neurons were packed into a 3D space in random positions according to the density and ratio of morphological types found in corresponding living tissue."
According to the researchers, whose findings are published in this week's issue of the Proceedings of the National Academy of Sciences, the locations on the model matched that of synapses found in the equivalent real-brain circuit with 75 to 95 percent accuracy.
"Overall, this work represents a major acceleration in the ability to construct detailed models of the nervous system," according to the statement.