Posts tagged science
Articles and news from the latest research reports.
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.
Doctors have long recognized a link between alcoholism and anxiety disorders such as post-traumatic stress disorder (PTSD). Those who drink heavily are at increased risk for traumatic events like car accidents and domestic violence, but that only partially explains the connection. New research using mice reveals heavy alcohol use actually rewires brain circuitry, making it harder for alcoholics to recover psychologically following a traumatic experience.
“There’s a whole spectrum to how people react to a traumatic event,” said study author Thomas Kash, PhD, assistant professor of pharmacology at the University of North Carolina School of Medicine. “It’s the recovery that we’re looking at — the ability to say ‘this is not dangerous anymore.’ Basically, our research shows that chronic exposure to alcohol can cause a deficit with regard to how our cognitive brain centers control our emotional brain centers.”
The study, which was published online on Sept. 2, 2012 by the journal Nature Neuroscience, was conducted by scientists at the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and UNC’s Bowles Center for Alcohol Studies.
Flying High: Researchers Decipher Manic Gene
ScienceDaily (Sep. 1, 2012) — Flying high, or down in the dumps — individuals suffering from bipolar disorder alternate between depressive and manic episodes. Researchers from the University of Bonn and the Central Institute of Mental Health in Mannheim have now discovered, based on patient data and animal models, how the NCAN gene results in the manic symptoms of bipolar disorder.
(Credit: © Bastos / Fotolia)
The results have been published in the current issue of The American Journal of Psychiatry.
Individuals with bipolar disorder are on an emotional roller coaster. During depressive phases, they suffer from depression, diminished drive and often, also from suicidal thoughts. The manic episodes, however, are characterized by restlessness, euphoria, and delusions of grandeur. The genesis of this disease probably has both hereditary components as well as psychosocial environmental factors.
The NCAN gene plays a major part in how manias manifest
"It has been known that the NCAN gene plays an essential part in bipolar disorder," reports Prof. Dr. Markus M. Nöthen, Director of the Institute of Human Genetics at the University of Bonn. "But until now, the functional connection has not been clear." In a large-scale study, researchers led by the University of Bonn and the Central Institute of Mental Health in Mannheim have now shown how the NCAN gene contributes to the genesis of mania. To do so, they evaluated the genetic data and the related descriptions of symptoms from 1218 patients with differing ratios between the manic and depressive components of bipolar disorder.
Comprehensive data from patients and animal models
Using the patients’ detailed clinical data, the researchers tested statistically which of the symptoms are especially closely related to the NCAN gene. “Here it became obvious that the NCAN gene is very closely and quite specifically correlated with the manic symptoms,” says Prof. Dr. Marcella Rietschel from the Central Institute of Mental Health in Mannheim. According to the data the gene is, however, not responsible for the depressive episodes in bipolar disorder.
Manic mice drank from sugar solution with abandon
A team working with Prof. Dr. Andreas Zimmer, Director of the Institute of Molecular Psychiatry at the University of Bonn, examined the molecular causes effected by the NCAN gene. The researchers studied mice in which the gene had been “knocked out.” “It was shown that these animals had no depressive component in their behaviors, only manic ones,” says Prof. Zimmer. These knockout mice were, e.g., considerably more active than the control group and showed a higher level of risk-taking behavior. In addition, they tended to exhibit increased reward-seeking behavior, which manifested itself by their unrestrained drinking from a sugar solution offered by the researchers.
Lithium therapy also effective against hyperactivity in mice
Finally, the researchers gave the manic knockout mice lithium — a standard therapy for humans. “The lithium dosage completely stopped the animals’ hyperactive behavior,” reports Prof. Zimmer. So the results also matched for lithium; the responses of humans and mice regarding the NCAN gene were practically identical. It has been known from prior studies that knocking out the NCAN gene results in a developmental disorder in the brain due to the fact that the production of the neurocan protein is stopped. “As a consequence of this molecular defect, the individuals affected apparently develop manic symptoms later,” says Prof. Zimmer.
Opportunity for new therapies
Now the scientists want to perform further studies of the molecular connections of this disorder — also with a view towards new therapies. “We were quite surprised to see how closely the findings for mice and the patients correlated,” says Prof. Nöthen. “This level of significance is very rare.” With a view towards mania, the agreement between the findings opens up the opportunity to do further molecular studies on the mouse model, whose results will very likely also be applicable to humans. “This is a great prerequisite for advancing the development of new drugs for mania therapy,” believes Prof. Rietschel.
Source: Science Daily
When she was 9 years old, Camilla would entertain her friends by jumping off her bed and landing directly on her knees. She said she liked to hear the crunching sound they made—just like popcorn.
Another time, Camilla spent an entire school recess period walking around on a broken leg, without so much as a whimper, says neuroscientist India Morrison of the University of Gothenburg in Sweden. The child’s teachers didn’t believe Camilla when she said something was wrong, because she wasn’t sobbing or wailing in pain. Her father thought perhaps her leg needed massaging, but quickly realized the situation was much worse.
A CT scanner uses radiation to produce a three-dimensional image of the insides of the human body. X-rays are fired through the body, and scanners pick up the path of the rays, leading to a detailed image of the body. It can be used to detect and diagnose epilepsy, Alzheimer’s disease, cancers, heart disease and medical issue.
(Source: Daily Mail)
University of Tennessee Researchers Develop Comprehensive, Accessible Vision Testing Device
Eighty-five percent of children’s learning is related to vision. Yet in the United States, eighty percent of children have never had an eye exam or any vision screening before kindergarten, statistics say. When they do, the vision screenings they typically receive can detect only one or two conditions. Ying-Ling Chen, research assistant professor in physics at the University of Tennessee Space Institute in Tullahoma is working to change that with an invention that makes eye exams inexpensive, comprehensive, and simple to administer.
Languages are extremely diverse, but they are not arbitrary. Behind the bewildering, contradictory ways in which different tongues conceptualise the world, we can sometimes discern order. Linguists have traditionally assumed that this reflects the hardwired linguistic aptitude of the human brain. Yet recent scientific studies propose that language “universals” aren’t simply prescribed by genes but that they arise from the interaction between the biology of human perception and the bustle, exchange and negotiation of human culture.
Language has a logical job to do—to convey information—and yet it is riddled with irrationality: irregular verbs, random genders, silent vowels, ambiguous homophones. You’d think languages would evolve towards an optimal state of concision, but instead they accumulate quirks that hinder learning, not only for foreigners but also for native speakers.
These peculiarities have been explained by linguists by reference to the history of the people who speak it. That’s often fascinating, but it does not yield general principles about how languages have developed—or how they will change in future. As they evolve, what guides their form?
Amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease or ALS, is a devastating, rapidly advancing disease of the nerve cells in the brain and spinal cord that control voluntary muscle movement. But researchers at NYU School of Medicine have identified a new target for slowing the deterioration of physical function for which the disease is so well known.
In their new study, published August 30, 2012 online ahead of print in Cell Reports, lead investigator Steven J. Burden, PhD, and colleagues show that, by increasing the signaling activity of a protein called muscle skeletal receptor tyrosine-protein kinase (MuSK), they were able to keep nerve cells attached to muscle longer into the progression of the disease in a mouse model of ALS.