The marmoset brain, shown above, is about the size of a plum. By scanning a dissected brain for 24 hours, scientists were able to generate a map with a spatial resolution of 400 microns. “The image quality and resolution are much higher than we can obtain in a living subject,” says Wedeen.
As the brain rotates, you can see that all the neural fibers are visualized in half of the brain: the spiky fibers that look like pins in a pincushion are part of the cerebral cortex. The sparser half of the image displays only the fibers originating in the opposite side.
It’s easy to see that this brain lacks the folding that is characteristic of the human brain. “The human brain would look 25 times as complicated,” says Wedeen. “Every gyrus [fold] has its own story to tell.”
Credit: George Day, Van Wedeen, Ruopeng Wang at MGH, and John Kaas at Vanderbilt