Posts tagged science
Articles and news from the latest research reports.
Carbon nanotubes could one day enhance your brain
Swiss Federal Institute of Technology scientists found that carbon nanotubes offer the potential to establish functional links between neurons that could fight disease and enhance our brains.
The human brain contains about 10 billion neurons, each connecting to other nerve cells through 10,000 or more synapses. Neurons process signals from these connections, then produce output commands that stimulate biological functions, everything from breathing to thinking to kissing.
Many scientists consider our brain similar to a massive parallel processing system, a supercomputer. However, when that computer breaks down we can lose memory or worse, develop sicknesses such as Parkinson’s, Alzheimer’s or other forms of dementia.
Unfortunately, we can’t take our brain down to Wall Mart or Fry’s for an upgrade; however, what if we could put something in our brain that would enhance the signal processing capabilities of individual neurons. Swiss scientists say they’ve done just that with carbon nanotubes.
The forward-thinking research team; led by Michel Giugliano, now a professor at the University of Antwerp, created carbon nanotube scaffolds, which serve as electrical bypass circuitry, to not only repair faulty neural networks, but also enhance performance of healthy cells.
Although there are still some engineering hurdles to overcome, the scientists see huge potential for strengthening neural networks with carbon nanotubes. This procedure could allow brain-machine interfaces for neuroprosthetics that process sight, sound, smell and motion.
Such circuits might be used, for instance, to veto epileptic attacks before they occur, perform spinal bypasses around injuries, and repair or enhance normal cognitive functions. In the not-too-distant future, non-biological nano-neurons could enable our brains to process information much faster than today’s biological brains can.
Ontario man’s sight restored with help of stem cells
When Taylor Binns slowly began going blind because of complications with his contact lenses, he started to prepare for living the rest of his life without vision. But an innovative treatment using stem cells has changed all that, and returned to him the gift of sight.
Four years ago, while on a humanitarian work mission to Haiti, Binns developed intense eye pain and increasingly blurry vision. Doctors at home couldn’t figure out what was wrong and, over the next two years, Binns slowly went legally blind, no longer able to drive or read from his textbooks at Queens University, where he was studying commerce.
“Everything you could do before was being taken away, day by day, and it got worse and worse,” he recalls.
Doctors finally diagnosed him with a rare eye disease called corneal limbal stem cell deficiency, which was causing the normal cells on Binns’ corneas to be replaced with scar tissue, leading to painful eye ulcers that clouded over his corneas.
A variety of things can cause the condition, including chemical and thermal burns to the corneas, which are the glass “domes” over the coloured part of our eyes. But it’s also thought that microbial infections and wearing daily wear contact lenses for too long without properly disinfecting them can lead to the disease, too.
Since a corneal transplant was not an option for Binns, his doctors at Toronto Western Hospital proposed something new: a limbal stem cell transplant.
The limbus is the border area between the cornea and the whites of the eye where the eye normally creates new epithelial cells. Since Binns’ limbus was damaged, doctors hoped that giving him healthy limbal cells from a donor would cause healthy new cells to grow over the surface.
While the treatment is available in certain centres around the U.S., Binns became the first patient to try the treatment at a new program at Toronto Western Hospital.
“Within a month he could see 20/40,” says ophthalmologist Dr. Allan Slomovic. “His last visit he was 20/20 and 20/40.” Slomovic says “it’s extremely exciting” that the procedure was a success, “especially when you realize there is really nothing else that would have worked for him.”
Binns is now living pain-free, returning to doing everything he used to before his three-year sight loss. “Being able to see my computer, being able to go for a walk or a drive — I am so happy for that,” he says.
The Toronto team hopes to do many more of these procedures in the future, says Dr. Sherif El Defrawy from the Canadian Ophthalmological Society and University of Toronto’s ophthalmology department.
“We are already seeing this in a number of centres across the country and you will see it more and more as we understand how to improve the success rate,” he says.
For Binns, the experience has been life-changing in one more important way: He has now decided to switch his studies from commerce to medicine, and hopes to go to school to become an ophthalmologist.
MRI Could Solve Cellphone Radiation Problems
Years of studies to determine whether cellphones can cause brain tumors have yielded one popular consensus: More studies are needed. One important piece that has been missing from researchers’ arsenals is a way to see what happens to cellphone radiation that is absorbed by the human brain. Two scientists have now developed a magnetic resonance imaging (MRI) technique that they say could solve that problem. This could be an important tool for researchers who are trying to discover whether extensive cellphone use can cause brain tumors or other health problems.
The technique creates high-resolution 3-D images of the heat created by cellphone radiation absorbed in the brain. In research reported this week in Proceedings of the National Academy of Sciences, the scientists demonstrate the method on cow brain matter and a gel that emulates brain tissue. But the procedure could easily be adapted for tests on human brains, says David Gultekin, a medical physicist at Memorial Sloan-Kettering Cancer Center, in New York, who led the development of the technique.
MIT’s Sebastian Seung has turned mapping the neurons of the retina into a social game, all in the name of neuroscience.
The retina is one of the most easily dissectible parts of the neurological system, and easy to isolate, but “looks like garbage,” Seung says, speaking at Wired 2012. “You need to look at under the microscope. It’s such a complicated structure that it’s safe to say that it’s more than just a camera; it’s a computer that performs some of the tasks of visual perception”. To figure that how it performs those tasks requires mapping the “tangles of spaghetti” that are the neuron pathways between the cells of the retina, a small part of the overall quest to understand the machine that is the brain.
Many people, Seung says, are uncomfortable with the idea of the brain being a machine that can be understood as just a collection of parts. “Most people I talk with hear you’re a neuroscientist [and] they ask lots of questions. But in the end the conversation comes around to you not being able to explain how the mind works without invoking the soul,” he says. The brain is so complicated, though, that it’s no surprise that people would think that there must be more to it than just key parts.
To know that, though, requires building “a parts list” like the kind you might get with some popular Swedish furniture, says Seung — “but the parts list of the retina has frustrated neuroscientists for decades”. It currently runs to a hundred types of cell and counting.
The type of cell that Seung is particularly interested in is the J cell, which plays a role in detecting motion — but neuroscientists aren’t sure how. That’s why Seung and his colleagues launched Eyewire, a site where any amateur neuroscientist can log on and scroll through 3D scans of retinal neurons. Users mark out the paths the neurons trace from cell to cell, correcting the guesses the computer might have got incorrect. There’s even an international leaderboard for people to compete with each other for points.
Seung says: “Professional scientists can’t do it alone — we need amateur neuroscientists. It’s important because there are questions that we all care about, like, why don’t our brains work properly? Sometimes there are neurological disorders like Parkinson’s where the brain decays and dies, but in other disorders we don’t know what’s going on. Some have speculated that it’s wired differently, but how can you know if it’s wired differently without mapping the wires?”
(Source: wired.co.uk)
Simple Innovation to Electrodes Makes a Big Difference
The electroencephalogram (EEG) for human uses has been around since 1924. Small metal discs placed along the scalp measure electrical activity in the human brain, important in diagnosing or evaluating epilepsy, sleep disorders and other conditions.
But these electrodes have changed little since their introduction, and are far from perfect. Among other things, they pick up extraneous noise and movement in addition to brain wave activity, often making the readings difficult to interpret.
Walt Besio thinks he has a better way.
The National Science Foundation-funded scientist, who is associate professor of biomedical engineering at the University of Rhode Island, has invented a new and improved electrode, one that produces a performance difference that he says is akin to “taking the rabbit ears you used to have for your television set, and converting to high definition.”
His innovation is relatively simple, but apparently makes a big difference. Besio added two new metal rings around the basic disc, a change that eliminates outside noises and improves spatial resolution.
"EEG has two main problems: It’s very noisy and contaminated with artifacts, and it’s spatial resolution is bad," he explains. "We have improved the signal-to-noise ratio. It’s four times better than it was before. Because it is now a very local signal, it means we can put electrodes closer together, which improves spatial resolution, meaning you can better determine where the signal is coming from."
The additional rings work almost like an inner tube tossed on top of a rippling body of water. “The water is flat in the center of the inner tube and choppy on the outside,” he says. “The outer rings on the electrodes behave like that inner tube.”
For researchers and clinicians, having improved electrodes could open up potential new uses, as well as improve current ones-more accurate epilepsy diagnosis, for example, as well as the promise of “reading” someone’s thoughts in the future, with the goal, for example, of activating an otherwise inert body part, such as an arm or leg, and ultimately helping people with spinal cord injuries.
The aim is to have the highly sensitive electrodes first translate a person’s thoughts into electrical impulses that can be read by a computer, then, eventually move to robots, and later, limbs. Other scientists are conducting similar research, but Besio wants to show “that it works better with these types of electrodes.”
Research on multisensory speech perception in recent years has helped revolutionize our understanding of how the brain organizes the information it receives from our many different senses, UC Riverside psychology professor Lawrence D. Rosenblum writes in the January 2013 issue of Scientific American.
“Neuroscientists and psychologists have largely abandoned early ideas of the brain as a Swiss Army knife, in which many distinct regions are dedicated to different senses,” he says. “Instead scientists now think that the brain has evolved to encourage as much cross talk as possible between the senses — that the brain’s sensory regions are physically intertwined.”
The article, “A Confederacy of Senses,” explains how research in the past 15 years has demonstrated that no sense works alone. An abstract of the article can be read here.
“The multisensory revolution is also suggesting new ways to improve devices for the blind and deaf, such as cochlear implants,” Rosenblum writes. This research also has improved speech-recognition software, he says.
Researchers have discovered that the brain “does not channel visual information from the eyes into one neural container and auditory information from the ears into another, discrete, container as though it were sorting coins,” Rosenblum writes. “Rather our brains derive meaning from the world in as many ways as possible by blending the diverse forms of sensory perception.”
Rosenblum is the author of “See What I’m Saying: The Extraordinary Powers of Our Five Senses” (Norton, 2010), and has spent two decades studying multisensory perception, lipreading and hearing. His research has been supported by the National Science Foundation and the National Institutes of Health. He is known internationally for his research on risks the inaudibility of hybrid cars pose for blind and other pedestrians.
Help for when noses no longer smell properly
A psychological test, available for the first time, is intended to make the counselling and treatment of patients with olfactory dysfunction significantly easier. The new method has been developed by the University Department of Neurology at the MedUni Vienna.
The new investigation method provides the first easy-to-use testing process that measures subjective impairments caused by problems with the sense of smell. The test also examines how the impairment impacts on the patient’s quality of life. The aim of the test is to make targeted treatment and counselling to sufferers significantly easier in the future.
According to Gisela Pusswald, the developer of the test who works in the University Department of Neurology, patients often complain that their food no longer tastes like it used to and that they are unable to perceive perfumes or body odour at all, or only to a limited extent. The associated uncertainty of everyday living is often an even greater challenge. Says Pusswald: “Many patients are afraid that they will be unable to smell a gas leak if one occurs. The same goes for smoke, since they are unable to detect its smell.”
Worldwide, one in five people are affected by olfactory disturbances. The head of the test’s development, Johann Lehrner from the University Department of Neurology, explains why these conditions are extremely serious: “The debilitation of people with olfactory disturbances can be quite significant and can even cause persistent depressive states.” According to Lehrner, it is a worldwide phenomenon: “International studies estimate that one in five people worldwide aged between 20 and 90 have a disturbed sense of smell.”
English version of the test currently in development
The test, which has had its première in Vienna, was developed for the entire German-speaking region. Clinicians therefore now, for the first time, have a method that they can use and evaluate easily and one that delivers fast results. It gives experts the ability to very quickly obtain a good estimate of the extent of the problem. The German version of the test is currently being adapted for the English-speaking world.
Mild brain cooling after head injury prevents epileptic seizures in lab study
Mild cooling of the brain after a head injury prevents the later development of epileptic seizures, according to an animal study reported this month in the Annals of Neurology.
Epilepsy can result from genetics or brain damage. Traumatic head injury is the leading cause of acquired epilepsy in young adults. It is often difficult to manage with antiepileptic drugs. The mechanisms behind the onset of epileptic seizures after brain injury are not known . There is currently no treatment to cure it, prevent it, or even limit its severity.
The multi-institutional research team used a rodent model of acquired epilepsy in which animals develop chronic spontaneous recurrent seizures -the hallmark of epilepsy- after a contusive head injury similar to that causing epilepsy in humans. The rats were randomized to either mock-cooling or cooling of the contused brain by no more than 2 Celsius degrees. This degree of cooling, the authors explained, is known to be safe and to decrease mortality of patients with head injury. The rats were then monitored for four months after injury and epilepsy was evaluated by intracranial EEG. The contused brain was cooled continuously with special headsets engineered to passively dissipate heat. No Peltier cells or other power sources for refrigeration were needed.
The investigators report that cooling by just 2 degrees celsius for 5 weeks beginning 3 days after injury virtually abolished the later development of epileptic seizure activity. This effect persisted through the end of the study. The treatment induced no additional pathology or inflammation, and restored neuronal activity depressed by the injury.
“These findings demonstrate for the first time that prevention of epileptic seizures after traumatic brain brain injury is possible, and that epilepsy prophylaxis in patients could be achieved more easily than previously thought, said the lead author of the study, Raimondo D’Ambrosio, UW associate professor of neurological surgery. He added that a clinical trial is required to verify the findings in head injury patients.
Many causes for learning lags in tumor disorder
The causes of learning problems associated with an inherited brain tumor disorder are much more complex than scientists had anticipated, researchers at Washington University School of Medicine in St. Louis report.
The disorder, neurofibromatosis 1 (NF1), is among the most common inherited pediatric brain cancer syndromes. Children born with NF1 can develop low-grade brain tumors, but their most common problems are learning and attention difficulties.
“While one of our top priorities is halting tumor growth, it’s also important to ensure that these children don’t have the added challenges of living with learning and behavioral problems,” says senior author David H. Gutmann, MD, PhD, the Donald O. Schnuck Family Professor of Neurology. “Our results suggest that learning problems in these patients can be caused by more than one factor. Successful treatment depends on identifying the biological reasons underlying the problems seen in individual patients with NF1.”
The study appears online in Annals of Neurology.
According to Gutmann, who is director of the Washington University Neurofibromatosis Center, scientists are divided when considering the basis for NF1-associated learning abnormalities and attention deficits.
Mutations in the Nf1 gene can disrupt normal regulation of an important protein called RAS in the hippocampus, a brain region critical for learning. Initial work from other investigators had shown that increased RAS activity due to defective Nf1 gene function impairs memory and attention in some Nf1 mouse models.
However, earlier studies by Gutmann and collaborator David F. Wozniak, PhD, research professor in psychiatry, showed that a mutation in the Nf1 gene lowers levels of dopamine, a neurotransmitter involved in attention. In this Nf1 mouse model, Gutmann and his colleagues found that the branches of dopamine-producing nerve cells were unusually short, limiting their ability to make and distribute dopamine and leading to reduced attention in those mice.
The new research suggests that both sides may be right.
In the latest study, postdoctoral fellow Kelly Diggs-Andrews, PhD, found that the branches of dopamine-producing nerve cells that normally extend into the hippocampus are shorter in Nf1 mice. As a result, dopamine levels are lower in that part of the brain.
Charles F. Zorumski, MD, the Samuel B. Guze Professor and head of the Department of Psychiatry, showed that the low dopamine levels disrupts the ability of nerve cells in the hippocampus to modulate the way they communicate with each other. These communication adjustments are a primary way the brain creates memories.
Researchers then found that giving Nf1 mice L-DOPA, which increases dopamine levels, restored their nerve cell branch lengths to normal and corrected the hippocampal communication defect. L-DOPA also eliminated the memory and learning deficits in these mice.
“These results and the earlier findings suggest that there are a variety of ways that NF1 may cause cognitive dysfunction in people,” Gutmann says. “Some may have problems caused only by increased RAS function, others may be having problems attributable to reduced dopamine, and a third group may be having difficulties caused by both RAS and dopamine abnormalities.”
To customize patient therapy, Gutmann and his colleagues are now working to develop ways to quantify the contributions of dopamine and RAS to NF1-related learning disorders.
(Source: news.wustl.edu)
Re-tuning responses in the visual cortex
New research led by Shigeru Tanaka of the University of Electro-Communications and visiting scientist at the RIKEN Brain Science Institute has shown that the responses of cells in the visual cortex can be ‘re-tuned’ by experience.
Experiments on kittens in the 1960s showed that the primary visual cortex contains neurons that fire selectively to straight lines of specific orientations. These cells are organized into alternating columns that receive inputs from the left or right eye. The kitten experiments also showed that proper brain development is highly dependent on sensory information. Closing one eye altered the organization of the columns, so that those that should have received inputs from the closed eye were reduced in width, whereas those that received inputs from the open eye were much wider than normal.
The normal columnar organization can be restored if the closed eye is re-opened within a critical period of brain development. The effect of sensory experience on the orientation selectivity of neurons in the primary visual cortex is, however, unknown.
To investigate, Tanaka and his colleagues reared mice and fitted them with specially designed goggles through which they can only perceive vertically oriented visual stimuli, for a one-week period, between 3 and 15 weeks of age. Immediately after removing the goggles, they created a ‘window’ in the skull bone lying over the visual cortex to examine the cell response under the microscope.
Rearing the mice in this way had a significant effect on the properties of neurons in the primary visual cortex. The researchers found that the number of cells responding to vertical orientation increased, while the number responding to other orientation decreased. They also found that the extent of these changes depended on the age at which they fitted the animals with the goggles. Mice fitted with the goggles between 4 and 7 weeks of age had more cells that were sensitive to the experienced (vertical) orientation than those fitted later.
These findings show that there is a critical period of plasticity between 4 and 7 weeks, during which cells in the primary visual cortex are particularly sensitive to sensory experience and that plasticity persists in older animals, albeit to a lesser extent. They also suggest that plasticity in younger and older animals involves different mechanisms.
“When we put similar goggles on kittens, the age at which we started goggle rearing determined the reversibility of orientation selectivity,” says Tanaka. “We would now like to clarify the differences and commonalities of the mechanisms in cats and mice.”