The biggest to date three dimensional reconstruction of part of the human brain that shows in great detail each cell and network of neural connections, created by researchers at Harvard University and Google Research.

Their achievement is described in a publication in the journal “Science”.

The sample was obtained from a patient with epilepsy who underwent surgery.

Reconstruction concerns one cubic millimeter of brain tissue from the temporal cortexwhich however contains approximately 57,000 cells, 230 millimeters of blood vessels and nearly 150 million synapses.

The image shows excitatory neurons colored according to their depth from the surface of the brain. Blue neurons are closer to the surface and fuchsia marks the innermost layer. Credit: Google Research & Lichtman Lab (Harvard University). Renderings by D. Berger (Harvard University).

Using the data, the authors discovered previously underestimated aspects of the temporal cortex, including large numbers of glial cells above neurons, but also a rare but robust set of axons connected by up to 50 synapses.

The mapping will open the way to new insights into brain function and disease about which scientists still know very little.

The reconstruction resulted from a nearly decade-long collaboration at Harvard University, led by Jeff Lichtman, professor of molecular and cellular biology and newly appointed dean of science, with Google Research scientists.

The ultimate goal of the collaboration, which is supported by the US National Institutes of Health’s BRAIN Initiative, is to create a high-resolution map of the neurons in a mouse’s brain, which is estimated to require about 1,000 times the amount of data the one they just extracted from the section of human cortex.