A wickerwork brain? 3D brain structure of intersecting planes of inter-woven nerve fibres.
Using diffusion spectrum MRI, which maps nerve fibres by tracking the movement of water molecules, suggests that the brain consists of a three-dimensional grid of fibres on two-dimensional planes. The orientations of the grid correspond to up-down, right-left and front-back body axes laid down in the earliest stages of embryonic development and grow in the right direction by following simple developmental rules controlled by biochemical signals.
If the brain were organized like a tangle of spaghetti, says Wedeen, it would be difficult to see how mutations could lead to incremental changes in connectivity on which natural selection could act.
However, note that diffusion MRI can’t detect nerve fibres directly, so changes in machine set-up or data analysis could alter what is seen. Diffusion MRI detects the junctions of fibres and it is being argued that is likely to miss fibres criss-crossing in other orientations at angles less than about 70 degrees.
More details in Human brain organised like a 3D ‘New York City’ grid - health - 29 March 2012 - New Scientist