New High Resolution Scans Reveal 3D Grid Structure of Monkey and Human Brains

Posted on March 31, 2012

DSI Scan Showing 3D Grid Structure on Monkey Brain

Scientists have released new scans of a monkey brain from a Connectom diffusion magnetic resonance imaging (MRI) scanner that reveal a pervasive 3D grid structure with no diagonals. This scanner can visualize the networks of crisscrossing nerve fibers - by which different parts of the brain communicate with each other - in 10-fold higher detail than conventional scanners. The image above is detail from a DSI scan that revealed fabric-like 3D grid structure of connections in a monkey brain.

The grid structure also exists in human brains. The human brain's connections also turn out to be a an orderly 3D grid structure with no diagonals. This DSI image of a whole human brain shows folding of 2D sheets of parallel neuronal fibers that cross paths at right angles. The picture came from the new Connectom scanner. The video has no audio:

Van Wedeen, M.D., of Massachusetts General Hospital (MGH), A.A. Martinos Center for Biomedical Imaging and the Harvard Medical School, says, "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. This grid structure is continuous and consistent at all scales and across humans and other primate species."

Van Wedeen says previously, many scientists imagined a bowl of spaghetti when considering the structure of the brain. Van Wedeen says the grid structure was not obvious earlier because it is curved and bent.

NIMH Director Thomas R. Insel, M.D., says, "Getting a high resolution wiring diagram of our brains is a landmark in human neuroanatomy. This new technology may reveal individual differences in brain connections that could aid diagnosis and treatment of brain disorders."

In the study, researchers performed DSI scans on postmortem brains of four types of monkeys: rhesus, owl, marmoset and galago - and in living humans. They say they saw the same 2D sheet structure containing parallel fibers crossing paths everywhere in all of the brains. The grid structure of cortex pathways was continuous with those of lower brain structures, including memory and emotion centers. The more complex human and rhesus brains showed more differentiation between pathways than simpler species.

The study was funded, in part, by the NIH's National Institute of Mental Health (NIMH), the Human Connectome Project of the NIH Blueprint for Neuroscience Research, and other NIH components. It was reported here in the March 30, 2012 issue of the journal, Science Magazine.

Photo: Van Wedeen, M.D., Martinos Center and Dept. of Radiology, Massachusetts General Hospital and Harvard University Medical School