Tuesday, June 30, 2015
Monday, June 29, 2015
Textbooks got it wrong: How your brain understands words [feedly]
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Textbooks got it wrong: How your brain understands words
// Futurity.org
For 140 years, scientists' understanding of language comprehension in the brain came from individuals with stroke.
Based on language impairments caused by stroke, scientists believed a single area of the brain—a hotdog-shaped section in the temporal lobe of the left hemisphere called Wernicke's region—was the center of language comprehension. Wernicke's was thought to be responsible for understanding the meaning of single words and sentences, two separate and critical functions.
"There was some disconnect between what textbooks said and what we saw in our patients."
But scientists have updated and redrawn the traditional brain map of language comprehension based on new research with individuals who have a rare form of dementia that affects language, primary progressive aphasia (PPA).
The new research shows word comprehension is actually located in a different brain neighborhood—the left anterior temporal lobe, a more forward location than Wernicke's. And sentence comprehension turns out to be distributed widely throughout the language network, not in a single area as previously thought.
The paper was published in the journal Brain.
"This provides an important change in our understanding of language comprehension in the brain," says lead study author Marek-Marsel Mesulam, a neurology professor and director of Northwestern University's Cognitive Neurology and Alzheimer's Disease Center.
Knowing where language comprehension is located offers a more precise target for future therapies that could potentially protect or restore language function.
People who had strokes
Strokes cut off blood supply to regions of the brain and cause destruction of both neurons and fiber pathways passing through that region.
In the 1870s, a scientist named Carl Wernicke observed a specific region damaged by stroke and resulting language impairments. This area, consequently named Wernicke's region, was identified as the seat of language comprehension.
"People who had strokes that affected Wernicke's region couldn't explain what a word such as umbrella meant," Mesulam says. "Secondly, they had difficulty understanding sentence construction.
"If you said, 'Put the apple on top of the book,' even if they understood the meaning of apple and book, they wouldn't be able to carry out the command because they can't understand the construction of the sentence."
People with PPA
But Mesulam, the world's leading expert in PPA, for years had been puzzling over the fact that his PPA patients with damage in Wernicke's area did not have the word comprehension impairment seen in stroke patients. They still understood individual words. And their sentence comprehension was inconsistent; some understood sentences; some didn't.
"It was becoming clear over the many years I saw these patients that there was some disconnect between what textbooks said and what we saw in our patients," Mesulam says. "We did this study to analyze the discrepancy. The view of brain as seen from stroke did not match the view of the brain when seen from PPA."
He and colleagues began a study of PPA patients, conducting quantitative MRI imaging of their brains and testing their language.
Northwestern scientist Emily Rogalski conducted the imaging in 72 PPA patients with damage inside and outside of Wernicke's area. She measured cortex thickness in all of these areas.
Cortex thickness is an indirect measure of the number of neurons and brain health. Thinning of the cortex in PPA indicates the destruction of neurons by the disease.
Wernicke's area
Rogalski, a research associate professor, found PPA patients who lost cortical thickness in Wernicke's area still could understand individual words and had varied impairment of sentence comprehension. None of these patients had the global type of comprehension impairment described in stroke patients with Wernicke's aphasia.
Severe word comprehension loss was only seen in PPA patients who had diminished cortical thickness in a region of the brain completely outside of Wernicke's area, in the front part of the temporal lobe. This part of the brain is not prone to the effects of stroke, so its role in comprehension had been missed in prior language maps.
The discrepancy between the traditional map of comprehension and what was seen in PPA can be explained by the different ways the two diseases injure Wernicke's area.
In PPA, the neurodegenerative disease does not destroy the underlying fiber pathways that allow language areas to work together. But, in stroke patients, those critical highways passing through Wernicke's had been blown up. So, the messages from other parts of the brain to the left anterior temporal lobe—the spot for word comprehension—were simply not getting through, Mesulam suspects.
"What is happening here is no different from the charting of galaxies in outer space," Mesulam says. "You look through one kind of telescope, you see one picture; you look through another infrared telescope, you get another picture.
"We are all in this pursuit of how to piece together different perspectives to get a better sense of how the brain works.
"In this case, we saw a different map of language by comparing two different models of disease, one based on strokes that destroy an entire region of brain, cortex as well as underlying pathways, and the other on a neurodegenerative disease that attacks mostly brain cells in cortex rather than the region as a whole," Mesulam adds.
The National Institutes of Health funded the study.
Source: Northwestern University
The post Textbooks got it wrong: How your brain understands words appeared first on Futurity.
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His pain and her pain may not be the same [feedly]
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His pain and her pain may not be the same
// Futurity.org
Males and females process pain using different cells, a new study with mice suggests.
The findings could help researchers develop the next generation of medications for chronic pain—the most prevalent health condition humans face.
"Research has demonstrated that men and women have different sensitivity to pain and that more women suffer from chronic pain than men, but the assumption has always been that the wiring of how pain is processed is the same in both sexes," says co-senior author Jeffrey Mogil, professor of pain studies at McGill University and director of the Alan Edwards Centre for Research on Pain.
"The realization that the biological basis for pain between men and women could be so fundamentally different raises important research and ethical questions if we want to reduce suffering."
Pain blocker
Mogil and colleagues looked at the longstanding theory that pain is transmitted from the site of injury or inflammation through the nervous system using an immune system cell called microglia and discovered it is only true in males. Interfering with the function of microglia in a variety of different ways effectively blocked pain in male mice, but had no effect in females.
T cells, a completely different type of immune cell, appear to be responsible for sounding the pain alarm in female mice. However, exactly how this happens remains unknown.
"Understanding the pathways of pain and sex differences is absolutely essential as we design the next generation of more sophisticated, targeted pain medications," says co-senior author Michael Salter, a professor at the University of Toronto.
"We believe that mice have very similar nervous systems to humans, especially for a basic evolutionary function like pain, so these findings tell us there are important questions raised for human pain drug development."
The discovery comes as there is increased attention to the inclusion of female animals and cells in preclinical research. The US National Institutes of Health recently unveiled a new policy, similar to one already in place in Canada, to require the use of female animals and cell lines in preclinical research.
"For the past 15 years scientists have thought that microglia controlled the volume knob on pain, but this conclusion was based on research using almost exclusively male mice," Mogil says. "This finding is a perfect example of why this policy, and very carefully designed research, is essential if the benefits of basic science are to serve everyone."
The Canadian Institutes of Health Research, the Louise and Alan Edwards Foundation, the US National Institutes of Health, and SickKids Foundation funded the work. Researchers from Duke University also contributed. The findings appears in the journal Nature Neuroscience.
Source: McGill University
The post His pain and her pain may not be the same appeared first on Futurity.
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Friday, June 26, 2015
House bill would force Supreme Court justices onto Obamacare [feedly]
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House bill would force Supreme Court justices onto Obamacare
// Personal Liberty Digest™
A Texas congressman is floating a bill that aims to force the nine justices of the U.S. Supreme Court into the same Obamacare coverage they upheld in King v. Burwell.
Taking a cue from dissenting Justice Antonin Scalia, who quipped that Obamacare should henceforth be referred to as "SCOTUScare," Rep. Brian Babin (R-Texas) introduced the "SCOTUScare Act" on June 25.
In a statement on his congressional Web page, Babin said his bill would amend the Affordable Care Act so that the nine justices, as well as "Supreme Court staff," could obtain health coverage only by enrolling through an Obamacare exchange plan.
"As the Supreme Court continues to ignore the letter of the law, it's important that these six individuals [representing the majority opinion] understand the full impact of their decisions on the American people," Babin wrote. "That's why I introduced the SCOTUScare Act to require the Supreme Court and all of its employees to sign up for Obamacare. By eliminating their exemption from Obamacare, they will see firsthand what the American people are forced to live with!"
While Babin's idea will be received merely as a symbolic gesture, he's not alone in voicing substantive criticism of the court's majority opinion in the Burwell case.
Scalia was especially incensed with the six justices who voted to uphold the law, writing in his dissenting opinion that courts are, by the Constitution's design, inappropriate venues to resolve arguments over legislative intent.
"Our only evidence of what Congress meant comes from the terms of the law, and those terms show beyond all question that tax credits are available only on state Exchanges," he wrote.
"… The Court's decision reflects the philosophy that judges should endure whatever interpretive distortions it takes in order to correct a supposed flaw in the statutory machinery."
The post House bill would force Supreme Court justices onto Obamacare appeared first on Personal Liberty.
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