Brain wiring a simple grid, no diagonals

US researchers said the human brain is wired in a simple checkerboard grid pattern similar to that of woven cloth, with no diagonals or winding paths. Dr. Van Wedeen of the Martinos Center and Department of Radiology at the Massachusetts General Hospital and Harvard University Medical School in Boston said the brain appears to be wired more like the checkerboard streets of New York City than the curvy lanes of Columbia, Md. "Far from being just a tangle of wires, the brain's connections turn out to be more like ribbon cables -- folding 2D sheets of parallel neuronal fibers that cross paths at right angles, like the warp and weft of a fabric," Van Wedeen said in a statement. "This grid structure is continuous and consistent at all scales and across humans and other primate species." The discovery was possible because of a new Connectom diffusion magnetic resonance imaging scanner that can visualize the networks of crisscrossing fibers -- by which different parts of the brain communicate with each other -- in ten-fold higher detail than conventional scanners, Wedeen said. "This one-of-a-kind instrument is bringing into sharper focus an astonishingly simple architecture that makes sense in light of how the brain grows." The study, published in the journal Science, said as the brain gets wired up in early development, its connections form along perpendicular pathways, running horizontally, vertically and transversely -- and this grid structure appears to guide connectivity like lane markers on a highway, which would limit options for growing nerve fibers to change direction during development.