Posts tagged brain
Articles and news from the latest research reports.
Reduced Brain Connections Seen in People With Generalized Anxiety Disorder
A new University of Wisconsin-Madison imaging study shows the brains of people with generalized anxiety disorder (GAD) have weaker connections between a brain structure that controls emotional response and the amygdala, which suggests the brain’s “panic button” may stay on due to lack of regulation.
Anxiety disorders are the most common class of mental disorders and GAD, which is characterized by excessive, uncontrollable worry, affects nearly 6 percent of the population.
Lead author Dr. Jack Nitschke, associate professor of psychiatry in the UW School of Medicine and Public Health, says the findings support the theory that reduced communications between parts of the brain explains the intense anxiety felt by people with GAD.
In this case, two types of scans showed the amygdala, which alerts us to threat in our surroundings and initiates the “fight-or-flight” response, seems to have weaker “white matter” connections to the prefrontal and anterior cingulate cortex (ACC), the center of emotional regulation.
The researchers did two types of imaging - diffusion tensor imaging (DTI) and functional magnetic resonance (fMRI) - on the brains of 49 GAD patients and 39 healthy volunteers. Compared with the healthy volunteers, the imaging showed the brains of people with GAD had reduced connections between the prefrontal and anterior cingulate cortex and the amygdala via the uncinate fasciculus, a primary “white matter” tract that connects these brain regions. This reduced connectivity was not found in other white matter tracts elsewhere in their brains.
"We know that in the brain, if you use a circuit you build it up, the way you build muscle by exercise,” says Nitschke, a clinical psychologist who treats patients with anxiety disorders and does research at the UW-Madison’s Waisman Center.
Nitschke says that researchers wonder if this weak connection results in the intense anticipatory anxiety and worry that is the hallmark of GAD, because the ACC is unable to tell the amygdala to “chill out.” It also suggests that behavioral therapy that teaches patients to consciously exercise this emotional regulation works to reduce anxiety by strengthening the connection.
"It’s possible that this is exactly what we’re doing when we teach patients to regulate their reactions to the negative events that come up in everyone’s lives,” Nitschke says. "We can help build people’s tolerance to uncontrollable future events by teaching them to regulate their emotions to the uncertainty that surrounds those events.
(Source: news.wisc.edu)
Stem cells bring back feeling for paralysed patients
03 September 2012 by Andy Coghlan
For the first time, people with broken spines have recovered feeling in previously paralysed areas after receiving injections of neural stem cells.
(Image: Medical Images/Getty Images)
Three people with paralysis received injections of 20 million neural stem cells directly into the injured region of their spinal cord. The cells, acquired from donated fetal brain tissue, were injected between four and eight months after the injuries happened. The patients also received a temporary course of immunosuppressive drugs to limit rejection of the cells.
None of the three felt any sensation below their nipples before the treatment. Six months after therapy, two of them had sensations of touch and heat between their chest and belly button. The third patient has not seen any change.
"The fact we’ve seen responses to light touch, heat and electrical impulses so far down in two of the patients is very unexpected," says Stephen Huhn of StemCells, the company in Newark, California, developing and testing the treatment. "They’re really close to normal in those areas now in their sensitivity," he adds.
"We are very intrigued to see that patients have gained considerable sensory function," says Armin Curt of Balgrist University Hospital in Zurich, Switzerland, where the patients were treated, and principal investigator in the trial.
The data are preliminary, but “these sensory changes suggest that the cells may be positively impacting recovery”, says Curt, who presented the results today in London at the annual meeting of the International Spinal Cord Society.
Combat Stress in Afghanistan Could Alter Soldiers’ Long-term Neural Makeup
Some soldiers who serve in Afghanistan or other war-torn countries return home with visible injuries: concussions, broken bones or amputated limbs. Many others, though, suffer from injuries we can’t visibly see. The daily strain of being exposed to armed combat, enemy fire and unpredictable explosions can lead to a range of behavioral symptoms, including fatigue, slower reaction times and a difficulty in connecting to one’s immediate surroundings.
A new study of soldiers returning home from Afghanistan, published today online in the Proceedings of the National Academy of Sciences, hints at the underlying cause for these behavioral changes. Researchers from the Netherlands and elsewhere used neurological exams and MRI scanning techniques to examine 33 soldiers before and after a four-month deployment in NATO’s International Security Assistance Force, and compared them to a control group of 26 soldiers who were never deployed.
The results were sobering—and indicate that a relatively short period of combat stress can alter an individual’s neurological circuitry for a long time.
You already know it’s hard to balance your checkbook while simultaneously reflecting on your past. Now, investigators at the Stanford University School of Medicine — having done the equivalent of wire-tapping a hard-to-reach region of the brain — can tell us how this impasse arises.
The researchers showed that groups of nerve cells in a structure called the posterior medial cortex, or PMC, are strongly activated during a recall task such as trying to remember whether you had coffee yesterday, but just as strongly suppressed when you’re engaged in solving a math problem.
The PMC, situated roughly where the brain’s two hemispheres meet, is of great interest to neuroscientists because of its central role in introspective activities.
“This brain region is famously well-connected with many other regions that are important for higher cognitive functions,” said Josef Parvizi, MD, PhD, associate professor of neurology and neurological sciences and director of Stanford’s Human Intracranial Cognitive Electrophysiology Program. “But it’s very hard to reach. It’s so deep in the brain that the most commonly used electrophysiological methods can’t access it.”
Ιn a study published online Sept. 3 in Proceedings of the National Academy of Sciences, Parvizi and his Stanford colleagues found a way to directly and sensitively record the output from this ordinarily anatomically inaccessible site in human subjects. By doing so, the researchers learned that particular clusters of nerve cells in the PMC that are most active when you are recalling details of your own past are strongly suppressed when you are performing mathematical calculations.
Even in normal range, high blood sugar linked to brain shrinkage
September 3, 2012
People whose blood sugar is on the high end of the normal range may be at greater risk of brain shrinkage that occurs with aging and diseases such as dementia, according to new research published in the September 4, 2012, print issue of Neurology, the medical journal of the American Academy of Neurology.
"Numerous studies have shown a link between type 2 diabetes and brain shrinkage and dementia, but we haven’t known much about whether people with blood sugar on the high end of normal experience these same effects," said study author Nicolas Cherbuin, PhD, with Australian National University in Canberra.
The study involved 249 people age 60 to 64 who had blood sugar in the normal range as defined by the World Health Organization. The participants had brain scans at the start of the study and again an average of four years later.
Those with higher fasting blood sugar levels within the normal range and below 6.1 mmol/l (or 110 mg/dL) were more likely to have a loss of brain volume in the areas of the hippocampus and the amygdala, areas that are involved in memory and cognitive skills, than those with lower blood sugar levels. A fasting blood sugar level of 10.0 mmol/l (180 mg/dL) or higher was defined as diabetes and a level of 6.1 mmol/l (110 mg/dL) was considered impaired, or prediabetes.
After controlling for age, high blood pressure, smoking, alcohol use and other factors, the researchers found that blood sugar on the high end of normal accounted for six to 10 percent of the brain shrinkage.
"These findings suggest that even for people who do not have diabetes, blood sugar levels could have an impact on brain health," Cherbuin said. "More research is needed, but these findings may lead us to re-evaluate the concept of normal blood sugar levels and the definition of diabetes."
Source: medicalxpress.com
Obesity and Metabolic Syndrome Associated With Impaired Brain Function in Adolescents
ScienceDaily (Sep. 3, 2012) — A new study by researchers at NYU School of Medicine reveals for the first time that metabolic syndrome (MetS) is associated with cognitive and brain impairments in adolescents and calls for pediatricians to take this into account when considering the early treatment of childhood obesity.
The study, funded by the National Institutes of Health under award number DK083537, and in part by award number 1ULIRR029892, from the National Center for Research Resources, appears online September 3 in Pediatrics.
As childhood obesity has increased in the U.S., so has the prevalence of metabolic syndrome — a constellation of three or more of five defined health problems, including abdominal obesity, low HDL (good cholesterol), high triglycerides, high blood pressure and pre-diabetic insulin resistance. Lead investigator Antonio Convit, MD, professor of psychiatry and medicine at NYU School of Medicine and a member of the Nathan Kline Research Institute, and colleagues have shown previously that metabolic syndrome has been linked to neurocognitive impairments in adults, but this association was generally thought to be a long-term effect of poor metabolism. Now, the research team has revealed even worse brain impairments in adolescents with metabolic syndrome, a group absent of clinically-manifest vascular disease and likely shorter duration of poor metabolism.
"The prevalence of MetS parallels the rise in childhood obesity," Dr. Convit said. "There are huge numbers of people out there who have problems with their weight. If those problems persist long enough, they will lead to the development of MetS and diabetes. As yet, there has been very little information available about what happens to the brain in the setting of obesity and MetS and before diabetes onset in children."
Researchers at the Hebrew University of Jerusalem have discovered that a neuronal pathway — part of the autonomic nervous system — reaches the bones and participates in the control of bone development.
The newly discovered pathway has a key role in controlling bone density during adolescence, which in turn determines the skeletal resistance to fracture throughout one’s entire life, say the researchers. They emphasize that understanding the mechanisms connecting the brain and the bones could have implications for possible future therapies to better deal with osteoporosis and various neural disorders. The findings of the Hebrew University team are published this week in the American journal PNAS (Proceedings of the National Academy of Sciences).
Vaughan Bell: how simulating dementia can help map our minds
Electrodes inside the skull can temporarily mimic brain disease – and so allow us to find out more about the way we work
Second thoughts: electrodes are inserted into a patient’s brain. Photograph: University of Utah Department of Neurosurgery
The first person to electrically stimulate the brain of a living human during surgery was the 19th-century British neurosurgeon Sir Victor Horsley. The operation was to treat a deformation called an encephalocele, where the bones of the skull do not close properly in the womb, causing the brain to protrude from the head. Horsely applied a weak electrical current to the surgically exposed brain tissue, making the patient’s eyes swivel to the side, which told the surgeon that the out-of-place area was the top of the midbrain – normally a deeply embedded neural structure essential for directing vision.
The technique was later picked up to treat epilepsy as it became clear that removing the part of the brain that triggered seizures could be an effective treatment, even if identifying it could be tricky. Small, clearly identified points of damage or localised tumours could often trigger seizures but sometimes the errant waves of epileptic activity would start far away from the original point of visible injury. Horsley used the electrical stimulation technique while patients were awake to find the sensitive area and remove it. Not bad for 1886.
Although initially invented for medical reasons, this surgical technique began to throw up some curious scientific data. In the 1930s the Canadian neurosurgeon Wilder Penfield asked patients undergoing epilepsy surgery if he could perform brief experiments while they were being operated on. He found that stimulating parts of the brain could cause a range of reactions from tingling to weeping to a “desire to move” – providing crucial evidence that activity in specific brain areas could trigger surprisingly complex behaviours.
People with epilepsy have remained an important part of our quest to understand ourselves as they have regularly volunteered to take part in neuroscience experiments while undergoing open-brain operations. Even though these experiments are a relatively brief pause in the procedure, they still require people to offer some of their time while their skull has been opened and their brain exposed, and we know much more about the brain thanks to their generosity.
As surgical techniques have moved on, so has the science. The starting points of some seizures are not easily located in the relatively short period available during surgery. To compensate for this, neurosurgeons have taken to implanting electrodes in the brains of people with epilepsy before the skull is replaced and the skin sewn up, which allows the medical team to record brain activity as the patients go about their daily life. One form of this “in brain” recording, known as electrocorticography, involves surgically inserting a grid of electrodes over the surface of the brain.
This has allowed neuroscientists to measure the brain at work in the real world via cables that go from the brain into a small digital recorder. A study published last year in the Journal of Neurosurgery mapped the main language areas of the cortex, the brain’s outer layer, using an implanted electrode grid and a simple word task that took an average of just 47 seconds. More than 100 other studies have used this technique with similarly impressive results.
One innovation is particularly mind-boggling. After years of using implanted electrode grids to read from the brain, neuroscientists have begun to use the electrodes to write to it – in other words, to alter the function of the brain through the same electrodes that record its activity. “By having a grid of electrodes in place,” says Matthew Lambon Ralph, professor of cognitive neuroscience at Manchester University, “it is possible to probe many different regions rather than just one.”
The precision is such that the Lambon Ralph team and a team at Kyoto University Medical School, led by Riki Matsumoto, have used an implanted grid to temporarily simulate characteristics of a brain disease called semantic dementia. Like Alzheimer’s, semantic dementia is a degenerative disorder, but one in which brain cells that specifically support our understanding of meaning rapidly decline. Studies of patients with semantic dementia have taught us a great deal about how memory is organised in the brain but the disorder is swift and unpredictable, and a method that can mimic the effects while recording directly from the cortex is a powerful tool.
The technique is safe and reversible, as we know from a simple version that is often done pre-neurosurgery to ensure that no tissue that supports key mental functions is removed during the operation. Using it as a way of briefly simulating more complex cognitive difficulties is an exciting development. “Stimulation is injected in one part of a grid and the evoked response across other grids is measured. It’s a direct measure of functional connectivity,” explains Lambon Ralph, highlighting how these sorts of studies can allow the brain’s function, in terms of thinking skills, to be closely linked to its physical connections.
The research was presented at the British Neuropsychological Society spring conference by UK-based team member Taiji Ueno. The main findings are still being prepared for peer review but the use of implant grids in neuroscience research is sure to become more common as the surgical procedure becomes more widely used.
These procedures are only done for medical reasons, and researchers get no say about how and on whom they are performed. But, as ever, patients have been generous with their time. From 1886 until now, these exciting discoveries have been made possible by people on the operating table.
(Source: Guardian)
A pain map of the brain being developed by scientists could finally put an end to the debate about whether women suffer more pain than men.
Using brain scanning technology, neuroscientists have been able to see how the brain responds to pain and map the signals to different parts of the body. They have also been able to measure how much pain someone is in from the signals in the brain.
Scientists have restored the sense of smell in mice through gene therapy for the first time — a hopeful sign for people who can’t smell anything from birth or lose it due to disease.
The achievement in curing congenital anosmia — the medical term for lifelong inability to detect odors — may also aid research on other conditions that also stem from problems with the cilia. Those tiny hair-shaped structures on the surfaces of cells throughout the body are involved in many diseases, from the kidneys to the eyes.
The new findings, published online in Nature Medicine, come from a team at the University of Michigan Medical School and their colleagues at several other institutions.