Posts tagged brain
Articles and news from the latest research reports.
Advanced brain investigations can become better and cheaper
A group of researchers at Chalmers University of Technology and the University of Gothenburg are now working on technology that can make MEG far more accessible. The vision is an MEG system that is simple and cheap enough to be available at every hospital, while furthermore providing totally new possibilities for fundamental investigations in brain research.
At the heart of the system is a new class of sensors that, unlike today’s MEG sensors, don’t require cooling to -269 Celsius. Instead, these work at -196 Celsius. This capability provides many advantages:
“One of them is the reduction of insulation between the sensors and the subject’s head,” says Dag Winkler, professor of physics at Chalmers. “The sensors can therefore get much closer to the brain so that one can take a more high-resolution picture of brain activity.”
With today’s technology, you can record activity from a patch of the brain that is roughly the size of a 1€ coin. With “Focal MEG” – MEG with liquid-nitrogen cooled sensors – the precision can be improved such that you’re recording from a patch of the brain that is a fraction of that size.
One example of what that can lead to is diagnosis of autism in children at a younger age – something that would be very meaningful considering how critical it is for these children to get the right help as early as possible.
“Another important advantage with Focal MEG is that the coolant the hardware requires is just liquid nitrogen”, Dag Winkler adds. “Today’s MEG requires liquid helium, which is extremely expensive. Furthermore, one can build the hardware with far more flexibility and less complication when using nitrogen instead of helium.”
The Gothenburg researchers have shown that Focal MEG works for advanced brain investigations. Using two sensors they developed, they have successfully recorded spontaneous brain activity –something that had never been done before with liquid-nitrogen cooled sensors. The ability to record spontaneous brain activity (as opposed to averaged activity from repetitive stimulation) is a solid indication that they can record more complicated brain activity.
“The prevailing assumption among MEG researchers has been that MEG with liquid-nitrogen cooled sensors isn’t feasible,” says Justin Schneiderman, assistant professor in biomedical engineering at the University of Gothenburg and MedTech West. “But now we’ve begun to expose holes in that assumption by demonstrating good sensitivity to two well-known brain waves from well-understood parts of the brain.”
The researchers have furthermore made an unexpected finding. They have recorded an uncharacteristically strong brain wave – the so-called theta rhythm – from the back of the brain. Today’s methods tend to find theta waves only in other parts of the brain.
“This is quite exciting,” says Mikael Elam, professor in clinical neurophysiology at the University of Gothenburg. “It may be an as-yet undetected type of brain signal that can only be found when one measures as close to the head as we do.”
(Source: chalmers.se)
A blood clot is one of the final steps in a complex process with which the human body seals a rupture in an injured blood vessel. Clotting involves interactions between millions of blood cells, microscopic cell fragments called platelets, and various proteins. First, platelets rush to the site of injury and join together with an inner layer of fibrin and collagen proteins to form a sticky web around the break. Red blood cells are then trapped in the web, forming a clot. In certain cases a clot can block arteries and vessels that feed the brain or heart, impeding blood flow and eventually contributing to a stroke or heart attack.
Creating accurate, real-time computer simulations of how blood clots work—and the role they play in medical emergencies—could, in the future, dramatically improve the way that doctors predict the risk of damaging clots and treat the damage incurred by strokes and heart attacks. The models could, for example, help doctors position a stent—a tube placed in a blood vessel to help keep it open—before a risky surgery or offer a new way to test the effects of drugs on the circulatory system. In order to be truly accurate and useful, however, such simulations would have to account for billions of tiny cellular machines, all moving through the blood—something that has never been comprehensively modeled before.
Study Details Brain Damage Triggered by Mini-Strokes
A new study appearing today in the Journal of Neuroscience details for the first time how “mini-strokes” cause prolonged periods of brain damage and result in cognitive impairment. These strokes, which are often imperceptible, are common in older adults and are believed to contribute to dementia.
“Our research indicates that neurons are being lost as a result of delayed processes following a mini-strokes that may differ fundamentally from those of acute ischemic events,” said Maiken Nedergaard, M.D., D.M.Sc., the lead author of the study and professor of Neurosurgery at the University of Rochester Medical Center (URMC). “This observation suggests that the therapeutic window to protect cells after these tiny strokes may extend to days and weeks after the initial injury.”
The prevalence of mini-strokes, or microinfarcts, has only been recently appreciated because common imaging techniques, such as MRI, are typically not sensitive enough to detect these microscopic injuries.
Similar to severe ischemic strokes, mini-strokes are caused when blood flow is blocked to a small area of the brain, usually by particle that travelled there from another part of the body. But unlike acute ischemic strokes – which bring about immediate symptoms such as numbness, blurry vision, and slurred speech – mini-strokes usually pass without notice. However, it is increasingly appreciated that these smaller strokes have a lasting impact on neurological function.
Microinfarcts are far more common than previously understood; it is believed that about 50 percent of individuals over the age of 60 have experienced at least one mini-stroke. Studies have also correlated the presence of mini-strokes with the symptoms of dementia. An estimated 55 percent of individuals with mild dementia and upwards of 70 percent of individuals with more severe symptoms show evidence of past mini-strokes. This association has led researchers to believe that these mini-strokes may be key contributors to age-related cognitive decline and dementia.
Nedergaard and her colleagues were the first to develop an animal model in which the complex progression and, ultimately, the cognitive impact of mini-strokes could be observed. Her team found that, in most instances, these strokes result in a prolonged period of damage to the brain.
Does the Brain Become Unglued in Autism?
A new study published in Biological Psychiatry suggests that autism is associated with reductions in the level of cellular adhesion molecules in the blood, where they play a role in immune function.
Cell adhesion molecules are the glue that binds cells together in the body. Deficits in adhesion molecules would be expected to compromise processes at the interfaces between cells, influencing tissue integrity and cell-to-cell signaling. In the brain, deficits in adhesion molecules could compromise brain development and communication between nerve cells.
Over the years, deficits in neural cell adhesion molecules have been implicated in schizophrenia and other psychiatric disorders. One adhesion molecule, neurexin, is strongly implicated in the heritable risk for autism.
Cell adhesion molecules also play a crucial role in regulating immune cell access to the central nervous system. Prior research provided evidence of immune system dysfunction in individuals diagnosed with autism spectrum disorder (ASD). This led scientists from the University of California, Davis to examine whether adhesion molecules are altered in children with ASD.
"For the first time, we show that levels of soluble sPECAM-1 and sP-selectin, two molecules that mediate leukocyte migration, are significantly decreased in young children with ASD compared with typically developing controls of the same age," explained the authors. "This finding is consistent with previous reports of decreased levels of both sPECAM-1 and sP-selectin in adults with high-functioning autism."
They also found that repetitive behavior scores and sPECAM-1 levels were associated in children with ASD. Repetitive, stereotyped behaviors are a typical feature of ASD and these data suggest a potential relationship between molecule levels and the severity of repetitive behaviors.
Finally, they also discovered that head circumference was associated with increased sPECAM-1 levels in the typically developing children, but not in the children with ASD. This indicates that perhaps sPECAM-1 plays a role in normal brain growth, as larger head circumference is a known feature of individuals with autism.
(Image courtesy of Cord Blood Registry)
The image of mental fatigue
Functional magnetic resonance imaging offers insights into mental fatigue
We all perhaps know the feeling of mental exhaustion, but what does it mean physiologically to have mental fatigue? A new study carried out using brain scans could help scientists uncover the neurobiological mechanisms underlying mental fatigue.
According to Bui Ha Duc and Xiaoping Li of the National University of Singapore writing in a forthcoming issue of the International Journal Computer Applications in Technology, mental fatigue has become commonplace as many people face increasing mental demands from stressful jobs, longer working hours with less time to relax and increasingly suffer sleep problems. Mental fatigue has received attention from those involved generally in health and well being as well as from the military and transport industry. After all, mental fatigue not only affects the health of individuals but can also have implications for road safety and international security.
The researchers used functional magnetic resonance imaging (fMRI) to monitor activity in the brains of ten student volunteers (male and female aged 19 to 25 years) deprived of sleep for 25 hours and given a simple task repeatedly through that period. They carried out scans at 9am, 2pm, 3am, 9am the following day. All volunteers had to have avoided alcohol and caffeine for the 24 hours prior to the experiment, were all physically and mentally fit prior to participation and none had any sleep problems.
The activation of the left thalamus increases with sleep deprivation, going in an exactly opposite trend to the inferior parietal that (following the circadian rhythm) decreases in activation from 9 am to 3 am next day and then increases in activation. This finding fits with logic as the inferior parietal cortex integrates information from different sensory modalities. As all the information has to go through the thalamus and then is sent by the thalamus to the inferior parietal, when the inferior parietal decreases in activation, the thalamus must increase its activation to get the information sent through.
The team explains that a gradual increase in mental fatigue led to decreased activity in the volunteers’ brains in specific regions: the anterior cingulate gyrus, right inferior frontal, left middle frontal and right superior temporal cortex. The anterior cingulate cortex has been described as an interface between motivation, cognition and action, and has been implicated in using reinforcement information to control behavior. The fMRI scans suggest that decreased activity in this part of the brain is therefore linked to those familiar feelings of mental fatigue including lethargy and slowness of thinking.
"The research provides a neurophysiologic basis for measuring the level of mental fatigue by EEG, as well as for the intervention by non-invasive neural stimulation to maintain wakefulness," the team says. "We have developed devices for both, which will be commercialized by our spinoff company, Newrocare Pte Ltd."
(Source: eurekalert.org)
Neuroscience: Under Attack
This fall, science writers have made sport of yet another instance of bad neuroscience. The culprit this time is Naomi Wolf; her new book, “Vagina,” has been roundly drubbed for misrepresenting the brain and neurochemicals like dopamine and oxytocin.
Earlier in the year, Chris Mooney raised similar ire with the book “The Republican Brain,” which claims that Republicans are genetically different from — and, many readers deduced, lesser to — Democrats. “If Mooney’s argument sounds familiar to you, it should,” scoffed two science writers. “It’s called ‘eugenics,’ and it was based on the belief that some humans are genetically inferior.”
Sharp words from disapproving science writers are but the tip of the hippocampus: today’s pop neuroscience, coarsened for mass audiences, is under a much larger attack.
Meet the “neuro doubters.” The neuro doubter may like neuroscience but does not like what he or she considers its bastardization by glib, sometimes ill-informed, popularizers.
Anatomical Brain Images Alone Can Accurately Diagnose Chronic Neuropsychiatric Illnesses
Objective
Diagnoses using imaging-based measures alone offer the hope of improving the accuracy of clinical diagnosis, thereby reducing the costs associated with incorrect treatments. Previous attempts to use brain imaging for diagnosis, however, have had only limited success in diagnosing patients who are independent of the samples used to derive the diagnostic algorithms. We aimed to develop a classification algorithm that can accurately diagnose chronic, well-characterized neuropsychiatric illness in single individuals, given the availability of sufficiently precise delineations of brain regions across several neural systems in anatomical MR images of the brain.
Methods
We have developed an automated method to diagnose individuals as having one of various neuropsychiatric illnesses using only anatomical MRI scans. The method employs a semi-supervised learning algorithm that discovers natural groupings of brains based on the spatial patterns of variation in the morphology of the cerebral cortex and other brain regions. We used split-half and leave-one-out cross-validation analyses in large MRI datasets to assess the reproducibility and diagnostic accuracy of those groupings.
Results
In MRI datasets from persons with Attention-Deficit/Hyperactivity Disorder, Schizophrenia, Tourette Syndrome, Bipolar Disorder, or persons at high or low familial risk for Major Depressive Disorder, our method discriminated with high specificity and nearly perfect sensitivity the brains of persons who had one specific neuropsychiatric disorder from the brains of healthy participants and the brains of persons who had a different neuropsychiatric disorder.
Conclusions
Although the classification algorithm presupposes the availability of precisely delineated brain regions, our findings suggest that patterns of morphological variation across brain surfaces, extracted from MRI scans alone, can successfully diagnose the presence of chronic neuropsychiatric disorders. Extensions of these methods are likely to provide biomarkers that will aid in identifying biological subtypes of those disorders, predicting disease course, and individualizing treatments for a wide range of neuropsychiatric illnesses.
Brain study shows why some people are more in tune with what they want
Wellcome Trust researchers have discovered how the brain assesses confidence in its decisions. The findings explain why some people have better insight into their choices than others.
Throughout life, we’re constantly evaluating our options and making decisions based on the information we have available. How confident we are in those decisions has clear consequences. For example, investment bankers have to be confident that they’re making the right choice when deciding where to put their clients’ money.
Researchers at the Wellcome Trust Centre for Neuroimaging at UCL led by Professor Ray Dolan have pinpointed the specific areas of the brain that interact to compute both the value of the choices we have in front of us and our confidence in those choices, giving us the ability to know what we want.
The team used functional magnetic resonance imaging (fMRI) to measure activity in the brains of twenty hungry volunteers while they made choices between food items that they would later eat. To determine the subjective value of the snack options, the participants were asked to indicate how much they would be willing to pay for each snack. Then after making their choice, they were asked to report how confident they were that they had made the right decision and selected the best snack.
It has previously been shown that a region at the front of the brain, the ventromedial prefrontal cortex, is important for working out the value of decision options. The new findings reveal that the level of activity in this area is also linked to the level of confidence participants placed on choosing the best option. The study also shows that the interaction between this area of the brain and an adjacent area reflects participants’ ability to access and report their level of confidence in their choices.
Dr Steve Fleming, a Sir Henry Wellcome Postdoctoral Fellow now based at New York University, explains: “We found that people’s confidence varied from decision to decision. While we knew where to look for signals of value computation, it was very interesting to also observe neural signals of confidence in the same brain region.”
Dr Benedetto De Martino, a Sir Henry Wellcome Postdoctoral Fellow at UCL, added: “Overall, we think our results provide an initial account both of how people make choices, and also their insight into the decision process.”
(Source: eurekalert.org)
Left brain people: process info in a linear manner, identify important details, are analytical, move in a sequential order, and use logic to solve problems.
Right brain people: process info holistically, see end results with clarity, are creative, move randomly form task to task, and use intuition to solve problems.
Why the Left-Brain Right-Brain Myth Will Probably Never Die?
The Science of Storytelling: Why Telling a Story is the Most Powerful Way to Activate Our Brains
We all enjoy a good story, whether it’s a novel, a movie, or simply something one of our friends is explaining to us. But why do we feel so much more engaged when we hear a narrative about events?
It’s in fact quite simple. If we listen to a powerpoint presentation with boring bullet points, a certain part in the brain gets activated. Scientists call this Broca’s area and Wernicke’s area. Overall, it hits our language processing parts in the brain, where we decode words into meaning. And that’s it, nothing else happens.
When we are being told a story, things change dramatically. Not only are the language processing parts in our brain activated, but any other area in our brain that we would use when experiencing the events of the story are too.