Brain Pathway Rediscovered After 100 Years
Modern magnetic resonance imaging (MRI) techniques are giving scientists unprecedented insight into the inner workings of the human brain. When neuroscientist Jason Yeatman of the University of Washington noticed a large fiber bundle that was unfamiliar to him and did not exist in modern scientific literature, he couldn’t believe he was actually the first person to discover the structure.
It turns out that he was right; the structure had been described before. However, the book that contained the last known mention of the fiber bundle had not been read in over 100 years. Yeatman and Kevin Wiener of Stanford University are co-authors of the paper, which was published in the Proceedings of the National Academy of Sciences.
The structure is now officially named the vertical occipital fasciculus (VOF). It is a tract of white matter that defies convention and connects areas of the brain vertically, rather than horizontally like most other white matter pathways. The pair used advanced MRI techniques and found that the pathway originates in a region at the back of the brain where visual processing occurs called the occipital lobe. Signals then spread out to many other regions in the brain, depending on what is required by the visual input.
“We believe that signals carried by the VOF play a role in many perceptual processes, from recognizing a friend’s face to rapidly reading a page of text,” Yeatman said in a press release.
The researchers also developed a computer algorithm for other neuroscientists to use that will allow measurements of the VOF to be completed more quickly. Since this structure has been forgotten for so long, there is a lot of catching up to do in learning about VOF’s function and determining if it can be targeted clinically to treat reading or visual disorders.
“To support reproducible research, our lab makes a strong effort to share software and data,” added senior author Brian Wandell of Stanford. “We believe this is a powerful way to ensure that our findings can be both checked and used in labs around the world.”
Credit: Yeatman, et al. (2014)
When Yeatman found the structure in the brain and was unable to identify it, he and Wiener started asking colleagues and searching through the literature. They were guided toward old anatomy books, dusting off progressively older tomes until they finally hit pay dirt.
“Kevin found an atlas, written by Carl Wernicke near the turn of the (20th) century, that depicted the vertical occipital fasciculus,” Yeatman explained. “The last time that atlas had been checked out was 1912, meaning we were the first to view these images in the last century.”
In addition to rediscovering the VOF, the researchers did more work and were able to find out why this structure essentially fizzled out from history. When neuroanatomist Carl Wernicke first identified the structure in 1881, its vertical orientation did not go over well with everyone else. Theodor Meynert, who led the field in his era, vehemently denied that pathways could go any other way but horizontally. Other scientists in the late 1800s had also made sketches of the structure, but inconsistent naming habits and criticism from the top brass in the field ultimately muddled the VOF into obscurity.
“When we started, it was just for our own knowledge and curiosity,” added Weiner. “But, after a while, we realized that there was an important story to tell that contained a series of missing links that have been buried for so long within this puzzle of historical conversation among many who are considered the founders of the entire neuroscience field.”
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