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Reliability of neuroscience research questioned
New research has questioned the reliability of neuroscience studies, saying that conclusions could be misleading due to small sample sizes.
A team led by academics from the University of Bristol reviewed 48 articles on neuroscience meta-analysis which were published in 2011 and concluded that most had an average power of around 20 per cent – a finding which means the chance of the average study discovering the effect being investigated is only one in five.
The paper, being published in Nature Reviews Neuroscience, reveals that small, low-powered studies are ‘endemic’ in neuroscience, producing unreliable research which is inefficient and wasteful.
It focuses on how low statistical power – caused by low sample size of studies, small effects being investigated, or both – can be misleading and produce more false scientific claims than high-powered studies.
It also illustrates how low power reduces a study’s ability to detect any effects and shows that when discoveries are claimed, they are more likely to be false or misleading.
The paper claims there is substantial evidence that a large proportion of research published in scientific literature may be unreliable as a consequence.
Another consequence is that the findings are overestimated because smaller studies consistently give more positive results than larger studies. This was found to be the case for studies using a diverse range of methods, including brain imaging, genetics and animal studies.
Kate Button, from the School of Social and Community Medicine, and Marcus Munafò, from the School of Experimental Psychology, led a team of researchers from Stanford University, the University of Virginia and the University of Oxford.
She said: “There’s a lot of interest at the moment in improving the reliability of science. We looked at neuroscience literature and found that, on average, studies had only around a 20 per cent chance of detecting the effects they were investigating, even if the effects are real. This has two important implications - many studies lack the ability to give definitive answers to the questions they are testing, and many claimed findings are likely to be incorrect or unreliable.”
The study concludes that improving the standard of results in neuroscience, and enabling them to be more easily reproduced, is a key priority and requires attention to well-established methodological principles.
It recommends that existing scientific practices can be improved with small changes or additions to methodologies, such as acknowledging any limitations in the interpretation of results; disclosing methods and findings transparently; and working collaboratively to increase the total sample size and power.
Researchers show brain’s battle for attention
We’ve all been there: You’re at work deeply immersed in a project when suddenly you start thinking about your weekend plans. It happens because behind the scenes, parts of your brain are battling for control.
Now, University of Florida researchers and their colleagues are using a new technique that allows them to examine how parts of the brain battle for dominance when a person tries to concentrate on a task. Addressing these fluctuations in attention may help scientists better understand many neurological disorders such as autism, depression and mild cognitive impairment.
Mingzhou Ding, a professor of biomedical engineering, and Xiaotong Wen, an assistant research scientist of biomedical engineering, both of the University of Florida; Yijun Liu of the McKnight Brain Institute of the University of Florida and Peking University, Beijing; and Li Yao of Beijing Normal University, report their findings in the current issue of The Journal of Neuroscience.
Scientists know different networks within the brain have distinct functions. Ding, Wen and their colleagues used a brain imaging technique called functional magnetic resonance imaging and biostatistical methods to examine interactions between a set of areas they call the task control network and another set of areas known as the default mode network.
The task control network regulates attention to surroundings, controlling concentration on a task such as doing homework, or listening for emotional cues during a conversation. The default mode network is thought to regulate self-reflection and emotion, and often becomes active when a person seems to be doing nothing else.
“We knew that the default mode network decreases in activity when a task is being performed, but we didn’t know why or how,” said Ding, a professor of biomedical engineering in the J. Crayton Pruitt department of biomedical engineering. “We also wanted to know what is driving that activity decrease.
“For a long time, the questions we are asking could not be answered.”
In the past, researchers could not distinguish between directions of interactions between regions of the brain, and could come up with only one number to represent an average of the back-and-forth interactions. Ding and his colleagues used a new technique to untangle the interactions in each direction to show how the different brain regions interact with one another.
In their study, the researchers used fMRI to examine the brains of people performing a task that required concentration. The scientists can see the activity in certain areas of the brain at the same time a person is performing a given task. They can see which parts of the brain are active and which are not and correlate this to how successful a person is at a given task. They then applied the Granger causality technique to look at the data they saw in the fMRI. Named for Nobel Prize-winning economist Clive Granger, this technique allows scientists to examine how one variable affects another variable; in this case, how one region of the brain influences another.
“People have hypothesized different functions for signals going in different directions,” Ding said. “We show that when the task control network suppresses the default mode network, the person can do the task better and faster. The better the default mode network is shut down, the better a person performs.”
However, when the default mode network is not sufficiently suppressed, it sends signals to the task control network that effectively distract the person, causing his or her performance to drop. So while the task control network suppresses the default mode network, the default mode network also interferes with the task control network.
“Your brain is a constant seesaw back and forth,” even when trying to concentrate on a task, Ding said.
The Granger causality technique may help researchers learn more about how neurological disorders work. Researchers have found that the default mode network remains unchanged in people with autism whether they are performing a task or interacting with the environment, which could explain symptoms such as difficulty reading social cues or being easily overwhelmed by sensory stimulation. Scientists have made similar findings with depression and mild cognitive impairment. However, until now no one has been able to address what areas of the brain might be regulating the default mode network and which might be interfering with that regulation.
“Now we are able to address these questions,” Ding said.
The Decade of the Brain: A Look at What Neuroscience Has in Store for Combating Disease
by Rachel Nuwer
Brain disorders affect more than 30 percent of the world’s population. In the U.S. alone, one in four families contends with the devastating impacts of Alzheimer’s, Parkinson’s, schizophrenia, depression, stroke or any of the other numerous ways our most complex organ can go awry.
President Obama’s recent announcement to create the BRAIN initiative—backed by a proposed $100 million in funds—acknowledges the severity of these problems and seeks to find solutions for them through an enhanced understanding of the brain. The U.S. is not alone in these endeavors. The European Union announced its own €800 million ($1.04 billion) Human Brain Project earlier this year.
Israel, too, is doing its part to better understand the human brain in order to combat conditions ranging from Alzheimer’s to epilepsy to brain trauma. At a gathering in San Francisco last week, neurophysiologist and neurosurgeon Alon Friedman of Ben-Gurion University of the Negev described some of the most promising research pursuits underway at the collaborative Zlotowski Center for Neuroscience. With the upsurge in research efforts and interest, he predicts that 2013 will kick off “the decade of the brain.”
Digital Media And The Moral Compass
Media culture should allow time for reflective moments, say USC neuroscientists in a study that also shows higher emotions to be as rooted in the body as primal impulses
Emotions linked to our moral sense awaken slowly in the mind, according to a new study from a neuroscience group led by corresponding author Antonio Damasio, director of the Brain and Creativity Institute at the University of Southern California.
The finding, contained in one of the first brain studies of inspirational emotions in a field dominated by a focus on fear and pain, suggests that digital media culture may be better suited to some mental processes than others.
“For some kinds of thought, especially moral decision-making about other people’s social and psychological situations, we need to allow for adequate time and reflection,” said first author Mary Helen Immordino-Yang.
Humans can sort information very quickly and can respond in fractions of seconds to signs of physical pain in others.
Admiration and compassion—two of the social emotions that define humanity—take much longer, Damasio’s group found.
Their study will appear next week in Proceedings of the National Academy of Sciences Online Early Edition.
“Damasio’s study has extraordinary implications for the human perception of events in a digital communication environment,” said media scholar Manuel Castells, holder of the Wallis Annenberg Chair of Communication Technology and Society at USC. “Lasting compassion in relationship to psychological suffering requires a level of persistent, emotional attention.”
The study’s authors used compelling, real-life stories to induce admiration for virtue or skill, or compassion for physical or social pain, in 13 volunteers (the emotion felt was verified through a careful protocol of pre- and post-imaging interviews).
Brain imaging showed that the volunteers needed six to eight seconds to fully respond to stories of virtue or social pain.
However, once awakened, the responses lasted far longer than the volunteers’ reactions to stories focused on physical pain.
The study raises questions about the emotional cost—particularly for the developing brain—of heavy reliance on a rapid stream of news snippets obtained through television, online feeds or social networks such as Twitter.
“If things are happening too fast, you may not ever fully experience emotions about other people’s psychological states and that would have implications for your morality,” Immordino- Yang said.
As a former public junior high school teacher who pioneered a doctoral thesis track on learning and the brain at Harvard University, and who holds a joint appointment in the Rossier School of Education along with her assistant professorship in the institute (part of the USC College of Letters, Arts and Sciences), Immordino-Yang stressed the study’s relevance to teaching.
“Educators are charged with the role of producing moral citizens who can think in ethical ways, who feel responsible to help others less fortunate, who can use their knowledge to make the world a better place,” she said.
“And so we need to understand how social experience shapes interactions between the body and mind, to produce citizens with a strong moral compass.”
Clearly, normal life events will always provide opportunities for humans to feel admiration and compassion.
But fast-paced digital media tools may direct some heavy users away from traditional avenues for learning about humanity, such as engagement with literature or face-to-face social interactions.
Immordino-Yang did not blame digital media. “It’s not about what tools you have, it’s about how you use those tools,” she said.
Castells said he was less concerned about online social spaces, some of which can provide opportunities for reflection, than about “fast-moving television or virtual games.”
“In a media culture in which violence and suffering becomes an endless show, be it in fiction or in infotainment, indifference to the vision of human suffering gradually sets in,” he said.
Damasio agreed: “What I’m more worried about is what is happening in the (abrupt) juxtapositions that you find, for example, in the news.
“When it comes to emotion, because these systems are inherently slow, perhaps all we can say is, not so fast.”
The study, titled “Neural Correlates of Admiration and Compassion,” takes a positive tack in research on emotion and the brain.
Damasio called the study “the first to investigate the neural bases of admiration and one of the first to deal with compassion in a context broader than physical pain. To say that admiration has been neglected is an understatement.”
Many previous studies have focused on negative emotions such as fear. By studying admiration, Damasio’s group is focusing on those impulses that bring out the best in humanity.
Admiration, Damasio said, “gives us a yardstick for what to reward in a culture, and for what to look for and try to inspire.”
He and Hanna Damasio, co-director of the institute and director of the Dornsife Imaging Center in the USC College, chose the study of admiration as one of the institute’s founding projects.
From Presidents Obama and Clinton to foster kids down the block, stories abound of individuals who have transcended their situations because of admiration for a key person in their lives.
“We actually separate the good from the bad in great part thanks to the feeling of admiration,” Damasio said. “It’s a deep physiological reaction that’s very important to define our humanity.”
It is also deeply rooted in the brain and the sense of the body, the study found, engaging primal neural systems that regulate blood chemistry, the digestive system and other parts of the body.
Damasio called it proof, pending replication of this study by other groups, that social emotions have deep evolutionary roots.
“People generally don’t think of emotions like admiration and compassion as having forerunners in evolution,” he noted.
“We reveal that these emotions engage the basic systems of our physiology.”
For Immordino-Yang, who focused on literature as an undergraduate, the study presented an intriguing test of the ancient poetic trope that compares deep emotion to physical injury—a “broken heart” being the obvious example.
“The poets had it right all along,” she said. “This isn’t merely metaphor. Our study shows that we use the feeling of our own body as a platform for knowing how to respond to other people’s social and psychological situations.
“These emotions are visceral, in the most literal sense—they are the biological expression of ‘do unto others as you would have them do unto you.’ “
Finally, the study showed that physical and social pain engage the posteromedial cortex, a central hub in the brain related to the sense of self and consciousness.
In keeping with that finding, volunteers reported a heightened sense of self-awareness after hearing the stories. Many expressed a desire to lead better lives. Some even refused the customary payment for participation, Immordino-Yang said.
Intriguingly, the posteromedial cortex appears to use different areas for responding to physical or social pain.
“The brain is honoring a distinction between things that have to do with physicality and things that have to do with the mind,” Damasio said.
Original Source - Eurekalert
Authors -Antonio Damasio
Functional ultrasound imaging tracks brain activity
Functional imaging modalities such as fMRI identify regions of brain activity by measuring changes in blood flow. But while fMRI offers excellent depth penetration, its sensitivity and temporal resolution are limited.
Now, researchers at the Institut National de la Santé et de la Recherche Médicale (INSERM) in Paris have come up with an alternative: functional ultrasound, an ultrasensitive imaging technique that can visualize whole-brain microvasculature dynamics with high spatiotemporal resolution (Nature Methods, August 2011, Vol. 8:8, pp. 662-664).
Previously, ultrasound’s low sensitivity meant that it could only be used to image blood flow within major vessels. To address this limitation, the INSERM researchers developed a high-speed imaging technique that can visualize flow in tiny brain vessels, where subtle variations are linked to cerebral activity. They claim that this functional ultrasound (fUS) method can image transient changes in blood volume with better resolution and sensitivity than previous functional brain imaging modalities.
With conventional ultrasound, tissue is scanned line by line with a focused beam. With a typical frame rate of about 50 frames per second, this process is too slow to acquire large-field images at the kilohertz rate required to image blood dynamics. To speed things up, fUS employs plane-wave illumination, in which a plane wave scans the whole image in a single shot. This boosts the frame rate up to about 10,000 frames per second.
“This means that, compared to conventional ultrasound, the number of time samples available for each pixel of the image is typically 100 times greater,” explained Mickaël Tanter, PhD, the research director at INSERM. “As we have many more time samples per pixel, we are able to detect much more subtle motion than in conventional ultrasound.”