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Lost region of brain rediscovered

By Stephen Morgan     Nov 19, 2014 in Health
Scientists have found a region of the brain which has been forgotten about for almost a century. And it isn't just some little grey blob, it is a massive part of the brain situated at the back of the head.
The neuroscientists who have rediscovered it describe it as a very important neural pathway, which appears to play an important role in perception. When its role is fully understood, the knowledge could provide new ways to help stroke patients and others with brain damage.
According to the Guardian, the region was first discovered in 1881 by the German scientist, Carl Wernicke, who was an expert neurologist working on stroke patients with language difficulties. Wernicke named it the vertical occipital fasciculus (VOF) which is a large collection of nerve fibres forming lengthy connections between visual regions in the back of the brain.
When it was first discovered, some leading neurologists refused to recognize its existence, because they believed brain pathways ran horizontally, while Wernicke insisted the VOF had vertical connections with other parts of the brain.
Despite the fact that Wernicke's findings were published in Gray's Anatomy in 1918, they became lost to the medical world until recently, when Jason Yeatman and his colleagues at Stanford University “stumbled across it,” while using neurological imaging techniques to study long-range connections between parts of the brain linked to language processing and reading skills.
Live Science reports Yeatman saying, "We'd thought we had discovered a new pathway that no one else had noticed before." To make sure, Yeatman and his colleagues set about trying to to find it in journals and medical literature, but it wasn't until someone remembered seeing it an old textbook that they found out that it had identified before. After that it had mysteriously disappeared from all scientific literature for almost a century.
The University of Washington website reports that Yeatman recounted how “Kevin found an atlas, written by Carl Wernicke near the turn of the (20th) century, that depicted the vertical occipital fasciculus. The last time that atlas had been checked out was 1912, meaning we were the first to view these images in the last century.” Bewildered, Yeatman exclaimed, "How did a whole piece of brain anatomy get forgotten?"
One reason maybe that it was given different names and in the confusion was lost from scientific knowledge. Another was that dissection techniques changed in the preceding period,
"You're slicing with a knife and trying to look for structure. It's very easy to miss something if you slice it a different way," Yeatman said.
Yeatman and his colleagues studied 74 patients to confirm the existence of the pathway and a new study of another 37 subjects confirms its location and what its role might be. Using MRI, they have mapped the region, in order to help scientist find and identify the VOF correctly.
Live Science reports that the research revealed that the VOF actually starts in the occipital lobe, which processes visual information. Dr. Jeremy Schmahmann, professor of neurology at Massachusetts General Hospital and Harvard Medical School explained,
“It then spreads out like a sheet, connecting different brain regions: those that help people perceive visual categories, such as words and faces, and those involved with eye movements, attention and motion perception... The pathway could therefore help explain how the brain connects the two types of visual perception.”
According to the Guardian, the VOF's “white matter..extends up through the brain for a distance of 5.5cm, connecting the ‘lower’ and ‘upper’ streams of the visual pathway. These run in parallel, and are sometimes called the ‘What’ and ‘Where’ pathways, for the type of information they carry: the lower stream, connects brain regions involved in processes such as object recognition, including the fusiform gyrus, and the upper stream connects the angular gyrus to other areas involved in attention, motion detection, and visually-guided behaviour."
Forgotten region of brain rediscovered
Forgotten region of brain rediscovered
Yeatman et al
It was found that people with damage to the VOF were no longer able to identify words and this resulted in them losing their ability to read. Yeatman told UW that, “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.”
However, researchers also think that its rediscovery may help to explain many more issues related to perception in general. Indeed, mysteries remain. Living Science says that the VOF was found to have different myelination, which is a nerve cells coating that makes information travel faster.
"We don't know what it means yet, but [the myelination differences are] very consistent across every subject," Yeatman said. "It opens up some new hypotheses, new directions to study: Why is this structure so different than the other neighboring pathways?"
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