Posts tagged neuroscience
Articles and news from the latest research reports.
A group of researchers has developed some exciting new techniques for imaging neuronal and synaptic networks using the hard synchrotron x-rays provided by the U.S. Department of Energy Office of Science’s Advanced Photon Source (APS).
These techniques provide images with unprecedented detail and resolution, and open the door to three-dimensional tomographic reconstructions, a vital tool for studying the complex tree-like branching nature of neuronal networks.
Understanding intricate neuronal and synaptic networks, particularly in more complex mammalian brains, requires high-resolution mapping of large volumes of tissue, preferably in three dimensions in order to capture all the subtle structural details.
"Mapping neuron networks has been providing a very significant understanding of how the brain works," said Yeukwang Hwu of Academia Sinica in Taipei, Taiwan, lead author of the paper on this new study, which was published in the Journal of Physics D: Applied Physics.
John Rogers of the University of Illinois at Urbana-Champaign and colleagues have designed a flexible circuit that can be worn over the fingertips. It contains layers of gold electrodes just a few hundred nanometres thick, sandwiched between layers of polyimide plastic to form a “nanomembrane”. This is mounted on a finger-shaped tube of silicone rubber, allowing one side of the circuit to be in direct contact with the fingertips. On the other side, sensors can be added to measure pressure, temperature or electrical properties such as resistance.
People wearing the device receive electrotactile stimulation – a tingling sensation caused by a small voltage applied to the skin. The size of the voltage is controlled by the sensor and varies depending on the properties of the object being touched.
Surgical gloves are one potential application. Rogers, who worked with colleagues at Northwestern University in Evanston, Illinois, and Dalian University of Technology in China, says gloves fitted with the nanomembrane could sense the thickness or composition of tissue via its electrical properties. A surgeon could also whittle away at the tissue using a high-frequency alternating current supplied by a battery attached at the wrist and delivered via the nanomembrane itself, says Rogers.
Woman’s missing digits grow back in phantom form
10 August 2012 by Helen Thomson
A woman born missing a finger and a thumb has grown them back – albeit as part of a phantom limb. This extraordinary occurrence shows that our brain contains a fully functional map of our body image, regardless of what our limbs actually look like.
The woman, RN, was born with just three fingers on her right hand. Aged 18, RN had the hand amputated after a car accident. She later began to feel that her missing limb was still present, and developed a “phantom” hand.
"But here’s the interesting thing," says Paul McGeoch at the University of California, San Diego. "Her phantom hand didn’t have three digits, it had five."
RN was aware of a full complement of fingers, but her phantom thumb and index finger were less than half the usual length.
With training using a mirror box trick – a tool that creates the visual illusion of two hands – McGeoch and V.S Ramachandran, also at San Diego, managed to extend her short phantom finger and thumb to normal length.
McGeoch says this study indicates that there is a hardwired representation in the brain of what the body should look like, regardless of how it actually appears in real life. It shows us more about the balance between the external and innate representations of a limb, he says.
"The presence of the deformed hand was suppressing the brain’s innate representation of her fingers which is why they appeared shorter, but after the hand was removed and the inhibition taken away, the innate representation kicks in again."
Matthew Longo at Birkbeck, University of London, says it is a fascinating case study. “It contributes to a growing literature suggesting that our conscious experience of our body is, at least in part, dependent on the intrinsic organisation of the brain, rather than a result of experience.”
Source: NewScientist
Research shows gene defect’s role in autism-like behavior
August 10, 2012
Scientists affiliated with the UC Davis MIND Institute have discovered how a defective gene causes brain changes that lead to the atypical social behavior characteristic of autism. The research offers a potential target for drugs to treat the condition.
Earlier research already has shown that the gene is defective in children with autism, but its effect on neurons in the brain was not known. The new studies in mice show that abnormal action of just this one gene disrupted energy use in neurons. The harmful changes were coupled with antisocial and prolonged repetitive behavior — traits found in autism.
The research is published online today in the scientific journal PLoS ONE.
"A number of genes and environmental factors have been shown to be involved in autism, but this study points to a mechanism — how one gene defect may trigger this type of neurological behavior," said study senior author Cecilia Giulivi, professor of molecular biosciences in the UC Davis School of Veterinary Medicine and a researcher affiliated with the UC Davis MIND Institute.
"Once you understand the mechanism, that opens the way for developing drugs to treat the condition," she said.
The defective gene appears to disrupt neurons’ use of energy, Giulivi said, the critical process that relies on the cell’s molecular energy factories called mitochondria.
In the research, a gene called pten was tweaked in the mice so that neurons lacked the normal amount of pten’s protein. The scientists detected malfunctioning mitochondria in the mice as early as 4 to 6 weeks after birth.
By 20 to 29 weeks, DNA damage in the mitochondria and disruption of their function had increased dramatically. At this time the mice began to avoid contact with their litter mates and engage in repetitive grooming behavior. Mice without the single gene change exhibited neither the mitochondria malfunctions nor the behavioral problems.
The antisocial behavior was most pronounced in the mice at an age comparable in humans to the early teenage years, when schizophrenia and other behavioral disorders become most apparent, Giulivi said.
The research showed that, when defective, pten’s protein interacts with the protein of a second gene known as p53 to dampen energy production in neurons. This severe stress leads to a spike in harmful mitochondrial DNA changes and abnormal levels of energy production in the cerebellum and hippocampus — brain regions critical for social behavior and cognition.
Pten mutations previously have been linked to Alzheimer’s disease as well as a spectrum of autism disorders. The new research shows that when pten protein was insufficient, its interaction with p53 triggered deficiencies and defects in other proteins that also have been found in patients with learning disabilities including autism.
Source: UCDavis
Singing mice (scotinomys teguina) are not your average lab rats. Their fur is tawny brown instead of the common white albino strain; they hail from the tropical cloud forests in the mountains of Costa Rica; and, as their name hints, they use song to communicate.
University of Texas at Austin researcher Steven Phelps is examining these unconventional rodents to gain insights into the genes that contribute to the unique singing behavior—information that could help scientists understand and identify genes that affect language in humans.
The song of the singing mouse is a rapid-fire string of high-pitched chirps called trills mostly used by males in dominance displays and to attract mates. Up to 20 chirps are squeaked out per second, sounding similar to birdsong to untrained ears. But unlike birds, the mice generally stick to a song made up of only a single note.
“They sound kind of soft to human ears, but if you slow them down by about three-fold they are pretty dramatic," said Phelps.
Migraines currently affect about 20 percent of the female population, and while these headaches are common, there are many unanswered questions surrounding this complex disease. Previous studies have linked this disorder to an increased risk of stroke and structural brain lesions, but it has remained unclear whether migraines had other negative consequences such as dementia or cognitive decline. According to new research from Brigham and Women’s Hospital (BWH), migraines are not associated with cognitive decline.
This study is published online by the British Medical Journal (BMJ) on August 8, 2012. “Previous studies on migraines and cognitive decline were small and unable to identify a link between the two. Our study was large enough to draw the conclusion that migraines, while painful, are not strongly linked to cognitive decline,” explained Pamela Rist ScD, a research fellow in the Division of Preventive Medicine at BWH, and lead author on this study.
Source: BWH
Schizophrenia and Psychosis – Brain Disease or Existential Crisis?
With the most recent schizophrenia/psychosis recovery research, we discover increasing evidence that psychosis is not caused by a disease of the brain, but is perhaps best described as being a last ditch strategy of a desperate psyche to transcend an intolerable situation or dilemma. To better understand how this conclusion which is so contrary to the widespread understanding of psychosis has come about, it will help if we break down this discussion into a short series of questions and answers.
Biologists try to engineer life that can survive on Mars and aid colonisation
With Nasa’s Curiosity Rover safely on Mars and ready to search for signs of life, back on Earth attempts are underway to engineer bacteria that could thrive on the Red Planet.
A team of undergraduates from Stanford and Brown Universities are busy applying synthetic biology to space exploration, outfitting microbes to survive extreme Martian conditions and produce resources needed to sustain a human colony.
Though Mars is potentially a place where life may have survived at some point, it is not an especially friendly environment, and thriving there will not be easy — for humans or microbes. The average surface temperature of Mars is minus 80 degrees Fahrenheit, and the almost-nonexistent atmosphere is 95 percent carbon dioxide. Although water exists in Mars’ ice caps and there’s some evidence that giant oceans once covered the planet, today it’s essentially a deep-frozen desert. Colonising Mars would be challenging and pricey.
'Selfish' DNA in animal mitochondria offers possible tool to study aging
Researchers at Oregon State University have discovered, for the first time in any animal species, a type of “selfish” mitochondrial DNA that is actually hurting the organism and lessening its chance to survive – and bears a strong similarity to some damage done to human cells as they age.
Such selfish mitochondrial DNA has been found before in plants, but not animals. In this case, the discovery was made almost by accident during some genetic research being done on a nematode, Caenorhabditis briggsae – a type of small roundworm.
“We weren’t even looking for this when we found it, at first we thought it must be a laboratory error,” said Dee Denver, an OSU associate professor of zoology. “Selfish DNA is not supposed to be found in animals. But it could turn out to be fairly important as a new genetic model to study the type of mitochondrial decay that is associated with human aging.”
Hormone in Fruit Flies Sheds Light On Diabetes Cure, Weight-Loss Drug for Humans
ScienceDaily (Aug. 9, 2012) — Manipulating a group of hormone-producing cells in the brain can control blood sugar levels in the body — a discovery that has dramatic potential for research into weight-loss drugs and diabetes treatment.
Erik Johnson uses the fruit fly, Drosophila, to look at an enzyme called AMP-activated kinase and its role in signaling the hormone that elevates the level of sugar in the blood. (Credit: Image courtesy of Wake Forest University)
In a paper published in the October issue of Genetics and available online now, neurobiologists at Wake Forest University examine how fruit flies (Drosophila) react when confronted with a decreased diet.
Reduced diet or starvation normally leads to hyperactivity in fruit flies — a hungry fly buzzes around feverishly, looking for more food. That happens because an enzyme called AMP-activated kinase stimulates the secretion of the adipokinetic hormone, which is the functional equivalent of glucagon. This hormone acts opposite of insulin, as it tells the body to release the sugar, or food, needed to fuel that hyperactivity. The body uses up its energy stores until it finds food.
But when Wake Forest’s Erik Johnson, an associate professor of biology, and his research team turned off AMP-activated kinase, the cells decreased sugar release and the hyperactive response stopped almost completely — even in the face of starvation.
"Since fruit flies and humans share 30 percent of the same genes and our brains are essentially wired the same way, it suggests that this discovery could inform metabolic research in general and diabetes research specifically," said Johnson, the study’s principal investigator. "The basic biophysical, biochemical makeup is the same. The difference in complexity is in the number of cells. Why flies are so simple is that they have approximately 100,000 neurons versus the approximately 11 billion in humans."
Medical advances as a result of this research might include:
• Diabetes research: Adipokinetic hormone is the insect equivalent to the hormone glucagon in the human pancreas. Glucagon raises blood sugar levels; insulin reduces them. However, it is difficult to study glucagon systems because the pancreatic cells are hard to pull apart. Studying how this similar system works in the fruit fly could pave the way to a drug that targets the cells that cause glucagon to tell the body to release sugar into the blood — thus reducing the need for insulin shots in diabetics.
• Weight-loss drugs: An “exercise drug” would turn on all AMP-activated kinase in the body and trick the body into thinking it was exercising. “Exercise stimulates AMP-activated kinase, so manipulation of this molecule may lead to getting the benefits of exercise without exercising,” Johnson said. In previous research published in the online journal PLoS ONE, Johnson and his colleagues found that, when you turn off AMP-activated kinase, you get fruit flies that “eat a lot more than normal flies, move around a lot less, and end up fatter.”
Source: Science Daily