MIAMI • Building on years of research, 82 researchers from institutions around the world have reported that they had built a reconstruction of a section of a rat brain in a computer.

The research was partly supported by the Human Brain Project, a 10-year European programme. The report comes directly from the Blue Brain Project that aims to reconstruct the rat brain and eventually the human brain in a computer.

Both programmes have been controversial. Hundreds of neuroscientists signed an open letter in 2014 criticising both the overall project and the feasibility of the reconstruction goal.

Mr Henry Markram, of the École Polytechnique Fédérale de Lausanne, who leads both projects, said what was achieved was the first draft of a functioning map of 30,000 brain cells. He said this was not yet a proof of principle that scientists could reconstruct the human brain, which contains 85 billion or more neurons, but it was a first step.

Ms Cori Bargmann, co-director of Kavli Neural Systems Institute at Rockefeller University, said the report represented an "amazing tour de force" but the "simulations are in their infancy". "They built a 747, and it's taxiing around the runway. I haven't seen it fly yet, but it's promising."

To build the digital rat brain, scientists used data from some cells to inform what the whole would look like. Then they simulated certain kinds of brain activity and found the reconstruction acted like the living tissue. The report was published in scientific journal Cell.

NEW YORK TIMES