Posts tagged science
Articles and news from the latest research reports.
Quality of white matter in the brain is crucial for adding and multiplying
‘Grey’ cells process information in the brain and are connected via neural pathways, the tracts through which signals are transferred.
"Neural pathways are comparable to a bundle of cables. These cables are surrounded by an isolating sheath: myelin, or ‘white matter’. The thicker the isolating sheath and the more cables there are, the more white matter. And the more white matter, the faster the signals are transferred," explains educational neuroscientist Bert de Smedt.
While the correlation between arithmetic and white matter tracts linking certain brain regions is known, very little research has been done to test this correlation in normally-developing children. Nor has previous research teased out differences in neuroactivity when carrying out different arithmetic operations, e.g., adding, subtracting, multiplying and dividing.
In this study, the researchers had 25 children solve a series of different arithmetic operations while undergoing a brain scan. They then compared the quality of the children’s white matter tracts with their arithmetic test performance.
"We found that a better quality of the arcuate fasciculus anterior – a white matter tract that connects brain regions often used for arithmetic – corresponds to better performance in adding and multiplying, while there is no correlation for subtracting and dividing.”
“A possible explanation for this is that this white matter bundle is involved in rote memorization, whereas when we subtract and divide, such memorization plays less of a role. When subtracting and dividing we are more likely to use intermediary steps to calculate the solution, even as adults.”
Nursery rhymes
These findings also add insight into the link between reading and arithmetic, explains Professor De Smedt: “Reading proficiency and arithmetic proficiency often go hand-in-hand. The white matter tract that we studied also plays an important role in reading: when we learn to read, we have to memorize the correspondence between particular letters and the sound they represent. It is likely that a similar process occurs for addition and multiplication. Just think of the notorious times-table drills we all memorized as schoolchildren; it is almost like learning a nursery rhyme. Some of us can even auto-recall these sums.”
"This also might explain why we often see arithmetic problems in children with dyslexia. Likewise, children with dyscalculia often have trouble reading," says Professor De Smedt.
The researchers now aim to explore how these results relate to children with impairments such as dyscalculia or head trauma. In a next step, the team will also investigate how white matter tracts can be strengthened through extra arithmetic training.
Groundbreaking Research Explores Link Between Traumatic Brain Injury and Sleep
It has long been believed that a person with a concussion should stay awake or not sleep for more than a few hours at a time.
But there appears to be no medical evidence to support that idea, according to a study regarding the relationship between traumatic brain injury, also known as TBI, and sleepiness conducted by scientists at Barrow Neurological Institute at Phoenix Children’s Hospital and the University of Arizona College of Medicine – Phoenix.
"This translational research study lays the foundation for understanding the immediate impact of brain injury on a person’s physiology. In this case, substantial post-traumatic sleep occurred regardless of injury timing or severity," said Jonathan Lifshitz, director of the Translational Neurotrauma Program at Barrow Neurological Institute at Phoenix Children’s Hospital and an associate professor at the UA College of Medicine – Phoenix. "These studies explore sleep as an immediate response to TBI."
Traumatic brain injury is a major cause of death and disability throughout the world with little pharmacological treatment for the individuals who suffer from lifelong problems associated with TBI. Clinical studies have provided evidence to support the claim that brain injury contributes to chronic sleep disturbances as well as excessive daytime sleepiness. Clinical observations have reported excessive sleepiness immediately following traumatic brain injury. However; there is a lack of experimental evidence to support or refute the benefit of sleep following a brain injury.
"We know that some individuals after a traumatic brain injury become excessively sleepy and some cannot sleep at all. It is not well understood why this occurs as mechanisms of injury, and locations of injury are not always consistent between clinical phenotypes of normal sleep, hypersomnia and insomnia," said Matthew Troester, a neurologist and sleep specialist at Phoenix Children’s Hospital and a clinical assistant professor at the UA College of Medicine – Phoenix.
Lifshiz and his associates are breaking new ground with descriptions of sleep in the acute – or immediately after injury – state, where little is known clinically, Troester added.
"They demonstrate that the subjects slept immediately and similarly post-injury no matter the severity of the injury or time of day the injury occurred. This tells us that the brain is reacting to the injury in a very specific manner – not something we always see clinically – and, ultimately, this may help us better understand what the role of sleep is in brain injury" such as being restorative, protective or merely a consequence of the injury, he said. "It is an exciting beginning."
This initial study is phase one of the Post-Traumatic Sleep Study. Phase two is in the works. The research will look to provide medical evidence for sleeping after a concussion.
(Source: uanews.org)
How does the brain create sequences?
When you learn how to play the piano, first you have to learn notes, scales and chords and only then will you be able to play a piece of music. The same principle applies to speech and to reading, where instead of scales you have to learn the alphabet and the rules of grammar.
But how do separate small elements come together to become a unique and meaningful sequence?
It has been shown that a specific area of the brain, the basal ganglia, is implicated in a mechanism called chunking, which allows the brain to efficiently organise memories and actions. Until now little was known about how this mechanism is implemented in the brain.
In an article published today (Jan 26th) in Nature Neuroscience, neuroscientist Rui Costa, and his postdoctoral fellow, Fatuel Tecuapetla, both working at the Champalimaud Neuroscience Programme (CNP) in Lisbon, Portugal, and Xin Jin, an investigator at the Salk Institute, in San Diego, USA, reveal that neurons in the basal ganglia can signal the concatenation of individual elements into a behavioural sequence.
"We trained mice to perform gradually faster sequences of lever presses, similar to a person who is learning to play a piano piece at an increasingly fast pace." explains Rui Costa. "By recording the neural activity in the basal ganglia during this task we found neurons that seem to treat a whole sequence of actions as a single behaviour."
The basal ganglia encompass two major pathways, the direct and the indirect pathways. The authors found that although activity in these pathways was similar during the initiation of movement, it was rather different during the execution of a behavioural sequence.
"The basal ganglia and these pathways are absolutely crucial for the execution of actions. These circuits are affected in neural disorders, such as Parkinson or Huntington’s disease, in which learning of action sequences is impaired", adds Xin Jin.
The work published in this article “is just the beginning of the story”, says Rui Costa. The Neurobiology of Action laboratory at the CNP, a group of around 20 researchers headed by Rui Costa, will continue to study the functional organisation of the basal ganglia during learning and execution of action sequences. Earlier this year, Rui Costa was awarded a 2 million euro Consolidation Grant by the European Research Council to study the mechanism of Chunking.
(Source: eurekalert.org)
E-Whiskers: Berkeley Researchers Develop Highly Sensitive Tactile Sensors for Robotics and Other Applications
From the world of nanotechnology we’ve gotten electronic skin, or e-skin, and electronic eye implants or e-eyes. Now we’re on the verge of electronic whiskers. Researchers with Berkeley Lab and the University of California (UC) Berkeley have created tactile sensors from composite films of carbon nanotubes and silver nanoparticles similar to the highly sensitive whiskers of cats and rats. These new e-whiskers respond to pressure as slight as a single Pascal, about the pressure exerted on a table surface by a dollar bill. Among their many potential applications is giving robots new abilities to “see” and “feel” their surrounding environment.
“Whiskers are hair-like tactile sensors used by certain mammals and insects to monitor wind and navigate around obstacles in tight spaces,” says the leader of this research Ali Javey, a faculty scientist in Berkeley Lab’s Materials Sciences Division and a UC Berkeley professor of electrical engineering and computer science. “Our electronic whiskers consist of high-aspect-ratio elastic fibers coated with conductive composite films of nanotubes and nanoparticles. In tests, these whiskers were 10 times more sensitive to pressure than all previously reported capacitive or resistive pressure sensors.”
Javey and his research group have been leaders in the development of e-skin and other flexible electronic devices that can interface with the environment. In this latest effort, they used a carbon nanotube paste to form an electrically conductive network matrix with excellent bendability. To this carbon nanotube matrix they loaded a thin film of silver nanoparticles that endowed the matrix with high sensitivity to mechanical strain.
“The strain sensitivity and electrical resistivity of our composite film is readily tuned by changing the composition ratio of the carbon nanotubes and the silver nanoparticles,” Javey says. “The composite can then be painted or printed onto high-aspect-ratio elastic fibers to form e-whiskers that can be integrated with different user-interactive systems.”
Javey notes that the use of elastic fibers with a small spring constant as the structural component of the whiskers provides large deflection and therefore high strain in response to the smallest applied pressures. As proof-of-concept, he and his research group successfully used their e-whiskers to demonstrate highly accurate 2D and 3D mapping of wind flow. In the future, e-whiskers could be used to mediate tactile sensing for the spatial mapping of nearby objects, and could also lead to wearable sensors for measuring heartbeat and pulse rate.
“Our e-whiskers represent a new type of highly responsive tactile sensor networks for real time monitoring of environmental effects,” Javey says. “The ease of fabrication, light weight and excellent performance of our e-whiskers should have a wide range of applications for advanced robotics, human-machine user interfaces, and biological applications.”
A paper describing this research has been published in the Proceedings of the National Academy of Sciences. The paper is titled “Highly sensitive electronic whiskers based on patterned carbon nanotube and silver nanoparticle composite films.” Javey is the corresponding author. Co-authors are Kuniharu Takei, Zhibin Yu, Maxwell Zheng, Hiroki Ota and Toshitake Takahashi.
(Source: newscenter.lbl.gov)
Infections damage our ability to form spatial memories
Increased inflammation following an infection impairs the brain’s ability to form spatial memories – according to new research. The impairment results from a decrease in glucose metabolism in the brain’s memory centre, disrupting the neural circuits involved in learning and memory.
Inflammation has long been linked to disorders of memory like Alzheimer’s disease. Severe infections can also impair cognitive function in healthy elderly individuals. The new findings published in the journal Biological Psychiatry help explain why inflammation impairs memory and could spur the development of new drugs targeting the immune system to treat dementia.
In the first trial to image how inflammation impairs human memory, the team at Brighton and Sussex Medical School scanned 20 participants before and after either a benign salty water injection or typhoid vaccination, used to induce inflammation. Positron emission tomography (PET) was used to measure the effects of inflammation on the consumption of glucose in the brain and after each scan participants tested their spatial memory by performing a series of tasks in a virtual reality.
A reduction in glucose metabolism within the brain’s memory centre, known as the Medial Temporal Lobe (MTL), was seen following inflammation. Participants also performed less well in spatial memory tasks, an effect that appeared to be directly mediated by the change in MTL metabolism.
"We have known for some time that severe infections can lead to long-term cognitive impairment in the elderly. Infections are also a common trigger for acute decline in function in patients with dementia and Alzheimer’s disease," explains Dr Neil Harrison, a Wellcome Trust Intermediate Clinical Fellow at BSMS who led the study. "This study suggests that catching a cold or the flu, which leads to inflammation in the brain, could impair our memory."
Infections are unlikely to cause long-term detrimental impact in the young and healthy but the findings are of great significance in the elderly. The team now plan to investigate the role of inflammation in dementia, including insight into how acute infections such as influenza influence the rate of progression and decline.
"Our findings suggest that the brain’s memory circuits are particularly sensitive to inflammation and help clarify the association between inflammation and decline in dementia," says Dr Harrison. "If we can control levels of inflammation, we may be able to reduce the rate of decline in patients’ cognition."
(Source: eurekalert.org)
How Inactivity Changes the Brain
A number of studies have shown that exercise can remodel the brain by prompting the creation of new brain cells and inducing other changes. Now it appears that inactivity, too, can remodel the brain, according to a notable new report.
The study, which was conducted in rats but likely has implications for people too, the researchers say, found that being sedentary changes the shape of certain neurons in ways that significantly affect not just the brain but the heart as well. The findings may help to explain, in part, why a sedentary lifestyle is so bad for us.
Until about 20 years ago, most scientists believed that the brain’s structure was fixed by adulthood, that you couldn’t create new brain cells, alter the shape of those that existed or in any other way change your mind physically after adolescence.
But in the years since, neurological studies have established that the brain retains plasticity, or the capacity to be reshaped, throughout our lifetimes. Exercise appears to be particularly adept at remodeling the brain, studies showed.
But little has been known about whether inactivity likewise alters the structure of the brain and, if so, what the consequences might be.
So for a study recently published in The Journal of Comparative Neurology, scientists at Wayne State University School of Medicine and other institutions gathered a dozen rats. They settled half of them in cages with running wheels and let the animals run at will. Rats like running, and these animals were soon covering about three miles a day on their wheels.
The other rats were housed in cages without wheels and remained sedentary.
Highly Reliable Brain Imaging Protocol Identifies Delays in Premature Infants
Infants born prematurely are at elevated risk for cognitive, motor, and behavioral deficits — the severity of which was, until recently, almost impossible to accurately predict in the neonatal period with conventional brain imaging technology. But physicians may now be able to identify the premature infants most at risk for deficits as well as the type of deficit, enabling them to quickly initiate early neuroprotective therapies, by using highly reliable 3-D MRI imaging techniques developed by clinician scientists at The Research Institute at Nationwide Children’s Hospital. The imaging technique also facilitates early and repeatable assessments of these therapies to help clinicians and researchers determine whether neuroprotective treatments are effective in a matter of weeks, instead of the two to five years previously required.
The researchers — experts in brain imaging and anatomy — developed a protocol for using the special imaging technique to study the development of 10 brain tracts in these tiny patients, work published online January 24 in PLOS One. Colorful 3-D images of each tract revealed the connections of the segments to different parts of the brain or the spinal cord. Each of the 10 tracts is important for certain functions and abilities, such as language, movement or vision.
“Developing a reliable and reproducible methodology for studying the premature brain was crucial in order for us to get to the next step: assessing neuroprotective therapies,” said Nehal A. Parikh, DO, principal investigator in the Center for Perinatal Research at Nationwide Children’s and senior author on the paper. “Now that we have this protocol, we can improve the standard of care and evaluate efforts to promote brain health within 8 to 12 weeks of beginning the interventions. That way, we can quickly see what really works.”
The study tested a detailed approach to measuring brain structure in extremely low birth weight infants at term-equivalent age by comparing their diffusion tensor tractography (DTT) scans to those of healthy, full-term newborns. DTT is a special MRI technique that produces 3-D images and is able to detect the brain’s structure and more subtle injuries than earlier forms of the technology.
The research team is the first to confirm differences in the fibrous structure of the 10 tracts between healthy, full-term infant brains and those of premature babies. Although the imaging technology is regularly used in adults, the tiny head size and lack of benchmark measurements in healthy infants meant that the use of DTT in premature infants was previously uncharted territory. With the detailed technique developed by Dr. Parikh’s team, the images can now be reproducibly processed and reliably interpreted.
“This protocol opens the field to far greater use of the methodology for targeting and assessing therapies in these infants,” said Dr. Parikh, who also is an associate professor of pediatrics at The Ohio State University College of Medicine. “We already have studies underway using our DTT segmentation methodology to measure the effectiveness of early neuroprotective interventions, such as the use of breast milk or skin-to-skin contact while premature babies are in intensive care.”
As imaging technology continues to be refined, the goal of targeted therapies based on the specific region of the brain with a delay or injury will become reality, Dr. Parikh predicted.For example, if an infant’s DTT scan indicates an under-developed corticospinal tract — the region of the brain controlling motor ability — physicians could immediately begin proactive physical therapies with the baby instead of waiting until the delay manifests itself. A repeat DTT scan a few months after beginning the therapy could then detect whether the therapy is effectively improving the structure of that brain tract.
“Because cognitive and behavioral deficits cannot be diagnosed until school age, there is an urgent need for robust early prognostic biomarkers,” said Dr. Parikh. “Our work is an important step in this direction and will facilitate early testing of neuroprotective interventions.”
(Source: nationwidechildrens.org)
Can Fish Oil Help Preserve Brain Cells?
People with higher levels of the omega-3 fatty acids found in fish oil may also have larger brain volumes in old age equivalent to preserving one to two years of brain health, according to a study published in the January 22, 2014, online issue of Neurology®, the medical journal of the American Academy of Neurology. Shrinking brain volume is a sign of Alzheimer’s disease as well as normal aging.
For the study, the levels of omega-3 fatty acids EPA+DHA in red blood cells were tested in 1,111 women who were part of the Women’s Health Initiative Memory Study. Eight years later, when the women were an average age of 78, MRI scans were taken to measure their brain volume.
Those with higher levels of omega-3s had larger total brain volumes eight years later. Those with twice as high levels of fatty acids (7.5 vs. 3.4 percent) had a 0.7 percent larger brain volume.
“These higher levels of fatty acids can be achieved through diet and the use of supplements, and the results suggest that the effect on brain volume is the equivalent of delaying the normal loss of brain cells that comes with aging by one to two years,” said study author James V. Pottala, PhD, of the University of South Dakota in Sioux Falls and Health Diagnostic Laboratory, Inc., in Richmond, Va.
Those with higher levels of omega-3s also had a 2.7 percent larger volume in the hippocampus area of the brain, which plays an important role in memory. In Alzheimer’s disease, the hippocampus begins to atrophy even before symptoms appear.
Honesty beats dishonesty for making you feel good
A University of Toronto report based on two neural imaging studies that monitored brain activity has found a reward given for telling the truth gives people greater satisfaction than the same reward given for deceit.
These studies were published recently in the neuroscience journals Neuropsychologia and NeuroImage.
"Our findings together show that people typically find truth-telling to be more rewarding than lying in different types of deceptive situations,” said Professor Kang Lee,whose research is funded in part by the Social Sciences and Humanities Research Council.
The findings are based on two studies of Chinese participants using a new neuroimaging method called near-infrared spectroscopy. The studies are among the first to address the question of whether lying makes people feel better or worse than telling the truth.
The studies explored two different types of deception. In first-order deception, the recipient does not know the deceiver is lying. In second-order deception, the deceivers are fully aware that the recipient knows their intention, such as bluffing in poker.
The researchers were surprised to find that a liar’s cortical reward system was more active when a reward was gained through truth-telling than lying. This was true in both types of deception.
Researchers also found that in both types of deception, telling a lie produced greater brain activations than telling the truth in the frontal lobe, suggesting lying is cognitively more taxing than truth-telling and uses more neural resources.
The researchers hope this study will advance understanding of the neural mechanisms underlying lying, a ubiquitous and frequent human behaviour, and help to diagnose pathological liars who may have different neural responses when lying or telling the truth.
Aspirin Intake May Halt Growth of Vestibular Schwannomas/Acoustic Neuromas
Researchers from Massachusetts Eye and Ear, Harvard Medical School, Massachusetts Institute of Technology and Massachusetts General Hospital have demonstrated, for the first time, that aspirin intake correlates with halted growth of vestibular schwannomas (also known as acoustic neuromas), a sometimes lethal intracranial tumor that typically causes hearing loss and tinnitus.
Image credit: Stanford School of Medicine/Oghalai Lab
Motivated by experiments in the Molecular Neurotology Laboratory at Mass. Eye and Ear involving human tumor specimens, the researchers performed a retrospective analysis of over 600 people diagnosed with vestibular schwannoma at Mass. Eye and Ear. Their research suggests the potential therapeutic role of aspirin in inhibiting tumor growth and motivates a clinical prospective study to assess efficacy of this well-tolerated anti-inflammatory medication in preventing growth of these intracranial tumors.
“Currently, there are no FDA-approved drug therapies to treat these tumors, which are the most common tumors of the cerebellopontine angle and the fourth most common intracranial tumors,” explains Konstantina Stankovic, M.D., Ph.D., who led the study. “Current options for management of growing vestibular schwannomas include surgery (via craniotomy) or radiation therapy, both of which are associated with potentially serious complications.”
The findings, which are described in the February issue of the journal Otology & Neurotology, were based on a retrospective series of 689 people, 347 of whom were followed with multiple magnetic resonance imaging MRI scans (50.3%). The main outcome measures were patient use of aspirin and rate of vestibular schwannoma growth measured by changes in the largest tumor dimension as noted on serial MRIs. A significant inverse association was found among aspirin users and vestibular schwannoma growth (odds ratio: 0.50, 95 percent confidence interval: 0.29-0.85), which was not confounded by age or gender.
“Our results suggest a potential therapeutic role of aspirin in inhibiting vestibular schwannoma growth,” said Dr. Stankovic, who is an otologic surgeon and researcher at Mass. Eye and Ear, Assistant Professor of Otology and Laryngology, Harvard Medical School (HMS), and member of the faculty of Harvard’s Program in Speech and Hearing Bioscience and Technology.
(Source: masseyeandear.org)