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Scientists Discover Secret Corridor Of Brain, Lost For 100 Years

Two years ago Jason Yeatman, a researcher at the University of Washington, stumbled into a secret corridor of the mind.

A graduate student at Stanford University at the time, Yeatman saw there was a bundle of fibers in the back of the brain, which he believes hasn’t been seen for 100 years.

In a paper published Monday for the Proceedings of the National Academy of Sciences, Yeatman and his co-authors tell the story of how science lost track of this part of the brain, and how he rediscovered it.  

Yeatman, who works at the UW’s Institute for Learning and Brain Sciences, now studies how the brain learns to read. As he told KUOW’s Marcie Sillman, the story begins a few years ago, when he was studying the Visual Wordform Area, a part of the brain that's important to reading. He was trying to understand the anatomy involved.

That's when he noticed something strange. Yeatman couldn't find the bundle of fibers in any of his anatomy textbooks, and for a while he thought he'd discovered it. His mentor started asking around – had anyone seen this?

A tip from a colleague sent him digging in Stanford's medical research library. He leafed through old atlases of the brain, looking for this specific bundle at the back of the brain. There, in a 1912 textbook of Gray’s Anatomy, he discovered the part of the brain that he had seen on the scans. Neuroscientists at the time would section monkey brains carefully, examining with the naked eye.

“We were pretty sure right away. The images were pretty conclusive,” Yeatman said.

Examining brain scans from 37 subjects, the researchers found that this lost part of the brain, called the vertical occipital fasciculus, begins at the back of the brain in the brain's visual processing system. The fibers there spread out like a sheet and connect brain regions that are important for seeing objects with others that coordinate which objects to focus attention upon.

The story of how this part of the brain was originally found, and then lost, has to do with a philosophical disagreement between the renowned brain scientist Carl Wernicke, and his mentor Theodor Meynert.

But the bundle didn’t make it into future textbooks because the fiber pathways defied the usual order – front to back. This bundle operated vertically, which created some conflict at the time, Yeatman said. Subsequently, half the brain schematics carried the image; the other half didn’t, creating a confusing story for future scientists.

Now that this part of the brain has been rediscovered, Yeatman is looking forward to exploring its role in how the brain learns to read.  

Produced for the Web by Isolde Raftery.

This story originally aired November 17, 2014