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Posts tagged ‘Functional magnetic resonance imaging’

Vegetative Ariel Sharon Shows ‘Significant’ Brain Activity.


Israel‘s former prime minister Ariel Sharon has been in what doctors have assumed is a vegetative state since 2006. But in a sign that not all of his critical brain processing has been lost, Sharon showed “significant” neural activity in tests using functional magnetic resonance imaging (fMRI), a team of scientists said.

During the two-hour test, Sharon was exposed to familiar stimuli, including pictures of his family and his son’s voice, and told to imagine himself performing different tasks, such as hitting a tennis ball and walking through the rooms of his home.

The scientists said they found promising signs that external information is being transferred to the right parts of Sharon’s brain, though it’s not clear that the 84-year-old former leader is aware of it.

“We found faint brain activity indicating that he was complying with the tasks,” Martin Monti, a UCLA brain scientist on the team, said in a statement. “He may be minimally conscious, but the results were weak and should be interpreted with caution.”

Paul Matthews, who heads the division of brain sciences at London’s Imperial College and was not involved in the tests on Sharon, said he thinks the results are encouraging from a clinical standpoint, but added it is hard to predict what they will mean for his future.

“Patients in a vegetative state may have brain function reserved in parts of the brain, yet will always remain in a vegetative state,” Matthews told LiveScience in a phone interview. “It is clear that regions of the brain associated with normal perception can respond to stimuli that we are not aware of at a conscious level.” [10 Greatest Mysteries of the Mind]

There’s no single part of the brain that is alone responsible for consciousness, Matthews added, and scientists don’t have a universal guide to tell them which spikes in brain activity (or blood flow, which is measured by fMRIs) in vegetative patients can be interpreted as signs meaningful, conscious activity in the mind. Matthews said that’s largely because tests using fMRI are generally not practical and only conducted in special cases.

While Sharon might represent one such special case, Tzvi Ganel, of Israel’s Ben-Gurion University of the Negev, who initiated the project, stressed that the former prime minister’s family hoped the tests would further research efforts and eventually help other families in a similar situation, according to a statement from UCLA.

Matthews noted that more tests on similar patients will be crucial for scientists. Analyzing the brains of enough people early enough in their injury could help researchers determine which flickers of activity might hint at recovery. And more tests on a wider spectrum of patients will help doctors flesh out the range of clinical outcomes for people with brain injuries that render them vegetative.

Source: YAHOO NEWS.

By Megan Gannon, News Editor | LiveScience.com

Follow LiveScience on Twitter @livescience. We’re also on Facebook & Google+.

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Big Bird Helps Scientists Study Brain Development.


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Children are not the only ones who can learn from Big Bird — brain scans of children and adults watching “Sesame Street” reveal how brains change as they learn reading and math, researchers say.

One goal of brain imaging is discovering more about how children learn. Such an understanding of the building blocks of learning might help diagnose and treat learning difficulties.

For instance, “when children fail to learn mathematics well, there could be a number of different reasons for that — it could be that they have weak concepts of numbers, that they have poor memory, that they have limited attention,” researcher Jessica Cantlon, a cognitive neuroscientist at the University of Rochester in New York, told LiveScience. Brain tests could help determine the precise cause of a kid’s math impairments, “because different patterns of brain activity likely accompany each of those different cognitive impairments.”

Although scientists currently cannot see what goes on in the brains of children when they are learning in the classroom, Cantlon and her colleagues instead focused on analyzing what happens when kids watched educational television programs.

For the investigation, 27 children between the ages of 4 and 11 joined 20 adults in watching the same 20-minute “Sesame Street” recording as they had their brains scanned with functional magnetic resonance imaging (fMRI). The video featured a variety of short clips with Big Bird, the Count, Elmoand other stars of the show, and focused on numbers, words, shapes and other subjects. The children then took standardized IQ tests for math and verbal ability. [See Elmo Video]

“This took three years,” Cantlon said. “Working with children can be challenging … It also took time for us to get the analyses right.”

Using statistical algorithms, the researchers created “neural maps” of the thought processes for the children and the adults and compared the groups. Children whose neural maps more closely resembled those of adults scored better on standardized math and verbal tests, showing that the brain’s neural structure, like other parts of the body, apparently develops along predictable pathways as people mature. [Inside the Brain: A Photo Journey Through Time]

This research also confirmed where these developing abilities are located in the brain. For math, adultlike neural patterns in the intraparietal sulcus, a region of the brain involved with the processing of numbers, were linked to higher scores. For verbal tasks, more mature patterns in Broca’s area, which is linked to speech and language, predicted better verbal test scores in children.

Normal activities such as TV watching may be a better way of learning about “neural maturity” than the short and simple tasks typical of fMRI studies. For instance, when the children matched simple pictures of faces, numbers, words or shapes, the neural responses of the children did not predict their test scores like watching “Sesame Street” did, the researchers said.

The researchers stress “that these results do not mean that there is anything special about ‘Sesame Street’ in particular,” Cantlon said. “We chose ‘Sesame Street’ because it is mainstream. There are likely lots of stimuli that could yield the same result.”

Still, while this research does not advocate watching television, it does show that “neural patterns during an everyday activity like watching television are related to a person’s intellectual maturity,” Cantlon said. “It’s not the case that if you put a child in front of an educational TV program that nothing is happening — that the brain just sort of zones out. Instead, what we see is that the patterns of neural activity that children are showing are meaningful and related to their intellectual abilities.”

Future studies can help pinpoint what areas might be linked with difficulties with learning math or verbal tasks. Research could also see if educational television shows are better than noneducational shows at eliciting math- and verbal-related brain activity, Cantlon said.

Cantlon and her colleague Rosa Li detailed their findings online Jan. 3 in the journal PLOS Biology.

Source: YAHOO NEWS.

By Charles Choi, LiveScience Contributor | LiveScience.com

Follow LiveScience on Twitter @livescience. We’re also on Facebook & Google+.

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

How Corn Syrup Might Be Making Us Hungry-and Fat.


 

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These fears may be well founded. Fructose, a new study finds, has a marked affect on the brain region that regulates appetite, suggesting that corn syrup and other forms of fructose might encourage over-eating to a greater degree than glucose. Table sugarhas both fructose and glucose, but high-fructose corn syrup, as the name suggests, contains a higher proportion of fructose.To test how fructose affects the brain, researchers studied 20 healthy adult volunteers. While the test subjects consumed sweetened beverages, the researchers used fMRIs (functional magnetic resonance imaging) to measure the response of the hypothalamus, which helps regulate many hunger-related signals, as well as reward and motivation processing.Volunteers received a 300-milliliter cherry-flavored drink sweetened with 75 grams (equivalent to about 300 calories) of fructose as well as the same drink sweetened with the same amount of glucose. These different drinks were given, in random order, at sessions one to eight months apart. The researchers also took blood samples at various time points and asked volunteers to rate their feelings of hunger and fullness.

Subjects showed substantial differences in their hypothalamic activity after consuming the fructose-sweetened beverage versus the one sweetened by glucose within 15 minutes. Glucose lowered the activity of the hypothalamus but fructose actually prompted a small spike to this area. As might be expected from these results, the glucose drink alone increased the feelings of fullness reported by volunteers, which indicates that they would be less likely to consume more calories after having something sweetened with glucose than something sweetened with more fructose.

Fructose and glucose look similar molecularly, but fructose is metabolized differently by the body and prompts the body to secrete less insulin than does glucose (insulin plays a role in telling the body to feel full and in dulling the reward the body gets from food). Fructose also fails to reduce the amount of circulating ghrelin (a hunger-signaling hormone) as much as glucose does. (Animal studies have shown that fructose can, indeed, cross the blood-brain barrier and be metabolized in the hypothalamus.) Previous studies have shown that this effect was pronounced in animal models.

The study, led by Kathleen Page, of Yale University School of Medicine and published online January 1 in JAMA, The Journal of the American Medical Association, was small and was not able to pinpoint precise neural circuits that might be affected by the sweeteners. But the results, along with other research, suggest that, thanks to the “advances in food processing and economic forces” that have boosted the intake of fructose, added sugar and high-fructose corn syrup are “indeed extending thesupersizing concept to the population’s collective waistlines,” wrote Jonathan Purnell, of the Division of Endocrinology, Diabetes, and Clinical Nutrition, and Damien Fair, of the Department of Behavioral Neuroscience, both of Oregon Health & Sciences University in Portland, who coauthored an essay that appeared in the same issue of JAMA.

Could fructose consumption alone really be playing such an outsized role in expanding our pant sizes? “A common counterargument is that it is the excess calories that are important, not the food. Simply put: just eat less,” Purnell and Fair noted. “The reality, however, is that hunger and fullness are major determinants of how much humans eat, just as thirst determines how much humans drink. These sensations cannot simply be willed away or ignored.” In order to eat less (and consume fewer calories overall), they argued, then, one should avoid foods or ingredients that fail to satisfy hunger. And that, according to the results from the new study, would mean those fructose-sweetened foods–and drinks.

© 2013 ScientificAmerican.com. All rights reserved.

Source: YAHOO NEWS.
By Katherine Harmon | Scientific American

What Makes ‘That Loving Feeling’?.


Ever wonder why brushing hands with your crush feels like a slow-motion caress, while that same brush of the hand by a bad date feels like a mistake?

Neuroscientists at         California Institute of Technology say the reason the same touch can be both attractive and repulsive may lie in the way the brain registers it.

In their study published  Monday in the Proceedings of the National Academy of Sciences, the researchers used functional magnetic resonance imaging to monitor the brain activity of 18 straight men as a female research participant gently stroked their legs.             

The men could  not  see the woman. Although the same woman caressed their legs, the first time  the men were told an attractive woman was caressing them, and the second time they were told it was a man. Before each part of the experiment, they were shown a video of  how to visualize the person caressing their leg, although, unknown  to the participants,  the image was not true to the actual person.

The researchers found that although the same person was giving the caresses, a part of the midsection of the brain called the primary somatosensory cortex became more active when the men believed  an attractive woman was  touching them  as opposed to a man.

“Intuitively, we all believe that when we are touched by someone, we first objectively perceive the physical properties of the touch – its speed, its gentleness, the roughness of the skin,” said Valerie Gazzola, a co-author of the study. “Only thereafter, in a separate, second step based on who touched us, do we believe we value this touch more or less.”

But the findings suggest that the primary somatosensory cortex is less objective than previously believed, and that the two parts to processing touch – one of understanding the physical component, and the other of assigning emotion to it –  may not necessarily be true, Gazzola said.

The primary somatosensory cortex is thought to  represent how touch feels on the skin, but the findings suggest that its activity is modified by what the participant thought of the caresser, according to Ralph Adolphs, a professor of psychology and neuroscience at Caltech and director of the Caltech Brain Imaging Center, where the experiment was carried out.

“We see responses in a part of the brain thought to process only basic touch that were elicited entirely by the emotional significance of social touch prior to the touch itself, simply in anticipation of the caress that our participants would receive,” said Adolphs.

These initial findings with only a small number of participants may not apply in a larger group. The researchers plan to test whether women’s brains would respond the same way as men’s did ,  and whether the brain would respond the same way across different sexual orientations.

“Nothing in our brain is truly objective,” said Christian Keysers, a co-author of the study. “Our perception is deeply and pervasively shaped by how we feel about the things we perceive.”

Source: YAHOO NEWS.

ABC NewsBy Lara Salahi | ABC News

What Makes ‘That Loving Feeling’?.


Ever wonder why brushing hands with your crush feels like a slow-motion caress, while that same brush of the hand by a bad date feels like a mistake?

Neuroscientists at         California Institute of Technology say the reason the same touch can be both attractive and repulsive may lie in the way the brain registers it.

In their study published  Monday in the Proceedings of the National Academy of Sciences, the researchers used functional magnetic resonance imaging to monitor the brain activity of 18 straight men as a female research participant gently stroked their legs.             

The men could  not  see the woman. Although the same woman caressed their legs, the first time  the men were told an attractive woman was caressing them, and the second time they were told it was a man. Before each part of the experiment, they were shown a video of  how to visualize the person caressing their leg, although, unknown  to the participants,  the image was not true to the actual person.

The researchers found that although the same person was giving the caresses, a part of the midsection of the brain called the primary somatosensory cortex became more active when the men believed  an attractive woman was  touching them  as opposed to a man.

“Intuitively, we all believe that when we are touched by someone, we first objectively perceive the physical properties of the touch – its speed, its gentleness, the roughness of the skin,” said Valerie Gazzola, a co-author of the study. “Only thereafter, in a separate, second step based on who touched us, do we believe we value this touch more or less.”

But the findings suggest that the primary somatosensory cortex is less objective than previously believed, and that the two parts to processing touch – one of understanding the physical component, and the other of assigning emotion to it –  may not necessarily be true, Gazzola said.

The primary somatosensory cortex is thought to  represent how touch feels on the skin, but the findings suggest that its activity is modified by what the participant thought of the caresser, according to Ralph Adolphs, a professor of psychology and neuroscience at Caltech and director of the Caltech Brain Imaging Center, where the experiment was carried out.

“We see responses in a part of the brain thought to process only basic touch that were elicited entirely by the emotional significance of social touch prior to the touch itself, simply in anticipation of the caress that our participants would receive,” said Adolphs.

These initial findings with only a small number of participants may not apply in a larger group. The researchers plan to test whether women’s brains would respond the same way as men’s did ,  and whether the brain would respond the same way across different sexual orientations.

“Nothing in our brain is truly objective,” said Christian Keysers, a co-author of the study. “Our perception is deeply and pervasively shaped by how we feel about the things we perceive.”

Source: YAHOO NEWS.

ABC NewsBy Lara Salahi | ABC News 

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