The rest are long-range fibers, which move information from these local, functionally similar regions to areas separated by significant physical, and likely also functional, distance. Some proportion of these form short-range connections with neurons that are both nearby in physical space, and are probably also close in “functional space” as well. So how much of a problem does the need for moving around information pose for brains and, by extension, brain-like computers? It’s clear from a cursory physical examination of the brain that evolution has prioritized information transfer, since the vast majority of brain tissue is taken up by the tendrils of axons and dendrites snaking through a convoluted maze of cables. And while manipulation of that information–”computation”–is an important component of what the brain does, it would be hard-pressed to make any use of that computational power without the ability to communicate within itself.

The brain’s precisely coordinated action relies on a dense network of fibers capable of rapidly transmitting information, both locally (to adjacent neurons whose separation can be measured in microns) and to distant locations removed by many centimeters from one another.

Length of myelinated fibers from white matter volume.

Myelination as indicative of fiber length.

Total length and distribution of lengths from morphological data.

Total length from neocortical fiber density.

Some important notes on brain structure and animal models.

Are there neurons outside the brain