Posts tagged neuroscience

March 14, 2012

Earlier evidence out of UCLA suggested that meditating for years thickens the brain (in a good way) and strengthens the connections between brain cells. Now a further report by UCLA researchers suggests yet another benefit.

Eileen Luders, an assistant professor at the UCLA Laboratory of Neuro Imaging, and colleagues, have found that long-term meditators have larger amounts of gyrification (“folding” of the cortex, which may allow the brain to process information faster) than people who do not meditate. Further, a direct correlation was found between the amount of gyrification and the number of meditation years, possibly providing further proof of the brain’s neuroplasticity, or ability to adapt to environmental changes.

The article appears in the online edition of the journal Frontiers in Human Neuroscience.

The cerebral cortex is the outermost layer of neural tissue. Among other functions, it plays a key role in memory, attention, thought and consciousness. Gyrification or cortical folding is the process by which the surface of the brain undergoes changes to create narrow furrows and folds called sulci and gyri. Their formation may promote and enhance neural processing. Presumably then, the more folding that occurs, the better the brain is at processing information, making decisions, forming memories and so forth.

"Rather than just comparing meditators and non-meditators, we wanted to see if there is a link between the amount of meditation practice and the extent of brain alteration," said Luders. "That is, correlating the number of years of meditation with the degree of folding."

The researchers took MRI scans of 50 meditators, 28 men and 22 women, and compared them to 50 control subjects matched for age, handedness and sex. The scans for the controls were obtained from an existing MRI database, while the meditators were recruited from various meditation venues. The meditators had practiced their craft on average for 20 years using a variety of meditation types — Samatha, Vipassana, Zen and more. The researchers applied a well-established and automated whole-brain approach to measure cortical gyrification at thousands of points across the surface of the brain.

They found pronounced group differences (heightened levels of gyrification in active meditation practitioners) across a wide swatch of the cortex, including the left precentral gyrus, the left and right anterior dorsal insula, the right fusiform gyrus and the right cuneus.

Perhaps most interesting, though, was the positive correlation between the number of meditation years and the amount of insular gyrification.

"The insula has been suggested to function as a hub for autonomic, affective and cognitive integration," said Luders. "Meditators are known to be masters in introspection and awareness as well as emotional control and self-regulation, so the findings make sense that the longer someone has meditated, the higher the degree of folding in the insula."

While Luders cautions that genetic and other environmental factors could have contributed to the effects the researchers observed, still, “The positive correlation between gyrification and the number of practice years supports the idea that meditation enhances regional gyrification.”

Provided by University of California - Los Angeles

Source: medicalxpress.com

March 14, 2012 By Bill Hathaway

The aging brain loses its ability to recognize when it is time to move on to a new task, explaining why the elderly have difficulty multi-tasking, Yale University researchers report.

“The aged brain seems to get lost in transition,” said Mark Laubach, associate professor at the John B. Pierce Laboratory and the Yale School of Medicine, and senior author of a study that appears in the March 14 issue of The Journal of Neuroscience.

Laubach’s team was studying the impact of aging on working memory, the type of memory that allows you to recall that dinner is in the oven when you are talking on the phone. The researchers examined brain activity in the medial prefrontal cortex of young and older rats that is related to spatial working memory — the type of memory that allows you to recall, for example, that mashed potatoes are on the stove and the turkey is in the oven

Based on previous studies, they expected that it would be spatial memory most affected by aging. Instead, the Yale team found that the aged brain seems to lose its ability to respond to cues that indicate when it is time to move on to a new task.

This ability to transition between tasks is critical for many daily activities, such as cooking dinner or handling situations that can arise in the workplace. The brain’s failure to monitor the timing of actions leads people to forget to turn off a burner on the stove while setting the table.

The research team found that neurons in the medial prefrontal cortex of older rats reacted more slowly to signals indicating that reward was available. Conversely, these signals immediately triggered a response in younger rats.

“Neurons in older rats fired fewer spikes in response to reward-predictive cues. The animals failed to respond immediately to the cues. They seemed to be stuck in time,” Laubach said.

Researchers hope that by understanding the mechanisms of working memory, scientists might one day be able to slow or perhaps eliminate deterioration of these brain functions over a lifespan, Laubach said.

Provided by Yale University

Source: medicalxpress.com

March 14, 2012

People with mild vascular disease that causes damage to the retina in the eye are more likely to have problems with thinking and memory skills because they may also have vascular disease in the brain, according to a study published in the March 14, 2012, online issue of Neurology, the medical journal of the American Academy of Neurology.

Damage to the retina is called retinopathy. In the study, the damage was mild enough to not cause significant symptoms.

"Problems with the tiny blood vessels in the eye may be a sign that there are also problems with the blood vessels in the brain that can lead to cognitive problems," said study author Mary Haan, DrPH, MPH, of the University of California, San Francisco. "This could be very useful if a simple eye screening could give us an early indication that people might be at risk of problems with their brain health and functioning."

The study involved 511 women with an average age of 69. The women took tests of their thinking and memory skills every year for up to 10 years. Their eye health was tested about four years into the study and scans were taken of their brains about eight years into the study.

A total of 39 women, or 7.6 percent, had retinopathy. The women with retinopathy on average had lower scores on the cognitive tests than the women who did not have retinopathy. The women with retinopathy also had more areas of small vascular damage within the brain, with 47 percent larger volumes of areas of damage than women who did not have retinopathy. In the parietal lobe of the brain, the women with retinopathy had 68 percent larger volumes of areas of damage.

The results remained the same even after adjusting for high blood pressure and diabetes, which can be a factor in vascular issues in the eye and the brain.

On a test of visual acuity, the women with retinopathy had similar scores as the women without the disease.

Provided by American Academy of Neurology

Source: medicalxpress.com

March 14, 2012 by Catherine Zandonella

(Medical Xpress) — Princeton University researchers have used a novel virtual reality and brain imaging system to detect a form of neural activity underlying how the brain forms short-term memories that are used in making decisions.

Using a virtual reality maze and brain imaging system, Princeton researchers have detected a form of neural activity the formation of short-term memories used in decision-making. These panels show the view of the virtual reality maze as seen by the mouse. The top panel shows a cue or sign that indicates to the mouse to turn right to receive a water reward. The middle panel shows a cue telling the mouse to turn left. The bottom panel shows the view at the T-intersection of the maze. (Image courtesy of Nature, Christopher Harvey and David Tank)

By following the brain activity of mice as they navigated a virtual reality maze, the researchers found that populations of neurons fire in distinctive sequences when the brain is holding a memory. Previous research centered on the idea that populations of neurons fire together with similar patterns to each other during the memory period.

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March 13, 2012

The next time you set a trap for that rat running around in your basement, here’s something to consider: you are going up against an opponent whose ability to assess the situation and make decisions is statistically just as good as yours.

A Cold Spring Harbor Laboratory (CSHL) study that compared the ability of humans and rodents to make perceptual decisions based on combining different modes of sensory stimuli—visual and auditory cues, for instance—has found that just like humans, rodents also combine multisensory information and exploit it in a “statistically optimal” way — or the most efficient and unbiased way possible.

"Statistically optimal combination of multiple sensory stimuli has been well documented in humans, but many have been skeptical about this behavior occurring in other species," explains Assistant Professor Anne Churchland, Ph.D., a neuroscientist who led the new study. "Our work is the first demonstration of its occurrence in rodents." The study appears in the March 14 issue of the Journal of Neuroscience.

This discovery is exciting, according to Churchland, because it suggests that the same evolutionarily conserved neural circuits underlie this behavior in both humans and rodents. “By observing this behavior in rodents, we have a chance to explore its neural basis – something that is not feasible to do in people,” Churchland says.

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ScienceDaily (Mar. 13, 2012) — A team of neuroscientists led by a Wayne State University School of Medicine professor has discovered stark developmental differences in brain network function in children of parents with schizophrenia when compared to those with no family history of mental illness.

The study, led by Vaibhav Diwadkar, Ph.D., assistant professor of psychiatry and behavioral neurosciences and co-director of the Division of Brain Research and Imaging Neuroscience, was published in the March 2012 issue of the American Medical Association journal Archives of General Psychiatry and is titled, “Disordered Corticolimbic Interactions During Affective Processing in Children and Adolescents at Risk for Schizophrenia Revealed by Functional Magnetic Resonance Imaging and Dynamic Causal Modeling.”

The results provide significant insight into plausible origins of schizophrenia in terms of dysfunctional brain networks in adolescence, demonstrate sophisticated analyses of functional magnetic resonance imaging (fMRI) data and clarify the understanding of developmental mechanisms in normal versus vulnerable brains. The resulting information can provide unique information to psychiatrists.

The study took place over three years, using MRI equipment at Harper University Hospital in Detroit. Using fMRI the researchers studied brain function in young individuals (8 to 20 years of age) as they observed pictures of human faces depicting positive, negative and neutral emotional expressions. Participants were recruited from the metropolitan Detroit area. Because children of patients are at highly increased risk for psychiatric illnesses such as schizophrenia, the team was interested in studying brain network function associated with emotional processing and the relevance of impaired network function as a potential predictor for schizophrenia.

To investigate brain networks, the researchers applied advanced analyses techniques to the fMRI data to investigate how brain regions dynamically communicate with each other. The study demonstrated that children at risk for the illness are characterized by reduced network communication and disordered network responses to emotional faces. This suggests that brain developmental processes are going awry in children whose parents have schizophrenia, suggesting this is a subgroup of interest to watch in future longitudinal studies.

"Brain network dysfunction associated with emotional processing is a potential predictor for the onset of emotional problems that may occur later in life and that are in turn associated with illnesses like schizophrenia," Diwadkar said. "If you clearly demonstrate there is something amiss in how the brain functions in children, there is something you can do about it. And that’s what we’re interested in."

The results don’t show whether schizophrenia will eventually develop in the subjects. “It doesn’t mean that they have it, or that they will have it,” he said.

"The kids we studied were perfectly normal if you looked at them," he said. "By using functional brain imaging we are trying to get underneath behavior."

"We are able to do this because we can investigate dynamic changes in brain network function by assessing changes in the fMRI signal. This allowed us to capture dramatic differences in how regions in the brain network are interacting with each other," he said.

According to the National Alliance on Mental Illness, schizophrenia affects men and women with equal frequency, but generally manifests in men in their late teens or early 20s, and in women in their late 20s or early 30s.

Source: Science Daily

ScienceDaily (Mar. 13, 2012) — A compound that previously progressed to Phase II clinical trials for cancer treatment slows neurological damage and improves brain function in an animal model of Alzheimer’s disease, according to a new study. The study published the week of March 13 in the Journal of Neuroscience shows that the compound epothilone D (EpoD) is effective in preventing further neurological damage and improving cognitive performance in a mouse model of Alzheimer’s disease (AD). The results establish how the drug might be used in early-stage AD patients.

This is an electron micrographic picture of a cross section of a nerve from an Alzheimer’s model mouse. Structural abnormalities in the nerve are indicated by the arrows. Alzheimer model mice that received the drug epothilone D had a significant reduction in the number of these abnormalities. (Credit: Zhang, et al. The Journal of Neuroscience 2012.)

Investigators from the Perelman School of Medicine at the University of Pennsylvania, led by first author Bin Zhang, MD, PhD, senior research investigator, and senior author Kurt R. Brunden, PhD, Director of Drug Discovery at the Center for Neurodegenerative Disease Research (CNDR), administered EpoD to aged mice that had memory deficits and inclusions within their brains that resemble the tangles formed by misfolded tau protein, a hallmark of AD. In nerve cells, tau normally stabilizes structures called microtubules, the molecular railroad tracks upon which cellular cargo is transported. Tangles may compromise microtubule stability, with resulting damage to nerve cells. A drug that could increase microtubule stability might improve nerve-cell function in AD and other diseases where tangles form in the brain.

EpoD acts by the same microtubule-stabilizing mechanism as the FDA-approved cancer drug paclitaxel (Taxol™). These drugs prevent cancer cell proliferation by over-stabilizing specialized microtubules involved in the separation of chromosomes during the process of cell division. However, the Penn researchers previously demonstrated that EpoD, unlike paclitaxel, readily enters the brain and so may be useful for treating AD and related disorders.

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March 13, 2012

Warm weather may hinder cognitive performance in people with multiple sclerosis (MS), according to results of a Kessler Foundation study e-published online ahead of print by Neurology. An accompanying editorial by Meier & Christodoulou, MS and heat: The smoke and the fire, details the study’s unique aspects, ie, longitudinal followup in a cohort with apparently quiescent disease.

Victoria M. Leavitt, Ph.D., research scientist at Kessler Foundation, is principal investigator for the study, which for the first time, shows a link between warm weather and cognition in people with MS. With more research, this information might help guide people with MS in making life decisions and assist their clinicians in choosing clinical treatment. Scientists may also want to consider the effect of warmer weather on cognition when designing and conducting clinical trials.

Kessler Foundation co-investigators are James F. Sumowski, Ph.D., Research Scientist, Nancy Chiaravalloti, Ph.D., Director of Neuropsychology & Neuroscience Research, and John DeLuca, Ph.D., Vice President for Research. All also have faculty appointments at UMDNJ-New Jersey Medical School.

Memory and processing speed were measured in 40 individuals with MS and 40 healthy people without MS. The study was conducted throughout the calendar year, and the daily temperature at the time of testing was recorded. The results showed that people with MS scored 70 percent higher on the tests on cooler days. There was no connection between daily temperature and cognitive performance for individuals without MS.

To confirm the effect of outdoor temperature, the group examined a separate sample of 45 persons with MS for whom cognitive tests were given at two sessions separated by a 6-month interval. For each person, cognitive performance was worse for testing during the warmer temperature. This finding is particularly important for researchers planning clinical trials with cognitive outcomes, especially since such trials frequently span a 6-month period. If baseline measurements of cognitive function are taken during warm months, the effect of the treatment may be inflated by the temperature effect. Cognitive performance may be a more sensitive indicator of subclinical disease activity than traditional assessments based on sensorimotor or EDSS (Expanded Disability Status score).

Provided by Kessler Foundation

Source: medicalxpress.com

Article Date: 13 Mar 2012 - 1:00 PDT

More than two-thirds of human genes have counterparts in the well-studied fruit fly, Drosophila melanogaster, so although it may seem that humans don’t have much in common with flies, the correspondence of our genetic instructions is astonishing. In fact, there are hundreds of inherited diseases in humans that have Drosophila counterparts.

At the Genetics Society of America’s 53rd Annual Drosophila Research Conference in Chicago, several scientific investigators shared their knowledge of some of these diseases, including ataxia-telangiectasia (A-T), a neurodegenerative disorder; Rett Syndrome, a neurodevelopmental disorder; and kidney stones, a common health ailment. All are the subject on ongoing research using the Drosophila model system.

Andrew Petersen, a graduate student in Dr. David Wassarman’s laboratory at the University of Wisconsin-Madison, discussed his experiments with a fly model of the rare childhood disease ataxia-telangiectasia. A-T causes cell death within the brain, poor coordination, characteristic spidery blood vessels that show through the skin, and susceptibility to leukemias and lymphomas. A-T generally results in a life expectancy of only 25 years.

A-T is normally lethal in flies, but Mr. Petersen induced a mutant that develops symptoms only when the environmental temperature rises above a certain level, allowing Mr. Petersen to control the lethality by varying the fly’s environment. The mutant flies lose their ability to climb up the sides of their vial habitats - a sign of neurodegeneration - and die prematurely. Their glial cells are primarily affected, rather than the neurons that the glia support. In addition, an innate immune response is activated in the compromised glia, a scenario reminiscent of Alzheimer’s and Parkinson’s diseases. “We are one step closer to knowing how these diseases occur and possibly how we can treat them,” Mr. Petersen concluded.

Sarah Certel, Ph.D., assistant professor of biological sciences at the University of Montana-Missoula, works with flies that have been altered to include the human gene MeCP2. This gene controls how neurons use many other genes, and the amount of the protein that it encodes must be within a specific range for the brain to develop normally. Too little of the protein and Rett syndrome results, a disorder on the X chromosome, which exclusively affects females in childhood. (Males with this mutation are generally miscarried or are stillborn.) It causes a constellation of symptoms including characteristic hand-wringing, autism, seizures, cognitive impairment, and loss of mobility. Yet too much of the protein causes similar problems.

In flies, altered levels of the MeCP2 protein affect sleep and aggression. For flies and most model organisms, sleep is inferred as the absence of activity during the day and night. To study sleep, Dr. Certel conducted “actograms” for individual flies. “The actogram records the activities of individually housed flies when they cross an infrared beam,” she explained. The flies’ sleep became fragmented, delayed, and shortened. “We’re studying the link between the cellular changes and behaviors,” she added.

Switching from the brain to the urinary system, it was noted that “Drosophila get kidney stones too” began Julian Dow, Ph.D., professor of molecular and integrative physiology at the University of Glasgow, United Kingdom. The fly version of a kidney is much simpler in design, a quartet of Malpighian tubules that are conveniently transparent.

Dr. Dow discussed a fly mutant called “rosy,” discovered a century ago, that corresponds to the rare human inborn error of metabolism called xanthinuria type 1, as well as a diet-induced blockage that corresponds to the more common human condition of calcium oxalate kidney stones. In time-lapse video, Dr. Dow showed stones appearing and growing in the Malpighian tubule.

“This was the first time in history that we saw kidney stones form - something that you cannot ethically do in humans,” he said. His research group, in collaboration with Dr. Michael Romero at the Mayo Institute, is now searching for chemical compounds that interfere with the formation of stones and their tendency to accrete into painful obstructions. They’ve already found a way to block a gene responsible for transporting the oxalate, slowing stone formation. With time, this work could help reduce the 250,000 emergency room admissions for kidney stones in the USA annually and the more than $2 billion in health care costs for treating them.

These were only three of several human diseases discussed at the Drosophila Conference. Others included oxidative stress, cancer linked to diabetes, amyloid build-up in Alzheimer’s disease, epilepsy, and muscular dystrophy. There are so many human diseases that have Drosophila counterparts that they are listed in a database called Homophila. Given the number that exist, we are certain to be learning more about our health from the fly in the years ahead.  

Source: Medical News Today

ScienceDaily (Mar. 13, 2012) — One of the trickiest parts of treating brain conditions is the blood brain barrier, a blockade of cells that prevent both harmful toxins and helpful pharmaceuticals from getting to the body’s control center. But, a technique published in JoVE, uses an MRI machine to guide the use of microbubbles and focused ultrasound to help drugs enter the brain, which may open new treatment avenues for devastating conditions like Alzheimer’s and brain cancers.

"It’s getting close to the point where this could be done safely in humans," said paper-author Meaghan O’Reilly, "there is a push towards applications."

The current method of disrupting the blood-brain barrier (BBB) is by using osmotic agents such as mannitol, which suck the water out of the cells that form the barrier, causing the gaps between them to get bigger. Unfortunately, this method opens large areas of the barrier, leaving the brain exposed to toxins.

The benefit of the microbubble technique is that it can be used on a very small area of the BBB. The microbubbles, made of lipids (fats) and gas, are injected into the blood stream. When focused ultrasound is applied, the bubbles expand and contract. It is thought that the force of the movement in the bubbles causes the cells that form the BBB to temporarily separate, which allows drugs to reach the brain.

"Microbubble technology has been around for years, though its applications have mostly been as contrast agents for diagnostic ultrasound," said JoVE Editorial Director, Dr. Beth Hovey. "This newer approach, using ultrasound to help the bubbles permeablize the blood brain barrier, will hopefully allow for better treatment of diseases within the brain."

In this method, O’Reilly and her colleagues use the MRI machine to ensure that the barrier opens, and they can also time how long it takes for it to close, which will be important for when the technique is used on patients.

"The ability of focused ultrasound combined with microbubbles to disrupt the blood brain barrier has been known for over a decade. However, because the actual technique can be challenging — there are critical steps involved — the video article fills a gap in the literature that is a major hindrance to people getting into the field," she said.

Source: Science Daily