Posts tagged neuroscience
Articles and news from the latest research reports.
New depression treatment may avoid side-effects
In an Australian first, researchers are studying Magnetic Seizure Therapy (MST) as an alternative treatment for the 30 per cent of patients suffering from depression who don’t respond to traditional treatment.
The treating team; Anne Maree Clinton, Dr Kate Hoy and Professor Paul Fitzgerald with the MST machine
The study, led by researchers from the Monash Alfred Psychiatry Research Centre (MAPrc) and funded by beyondblue and the National Health and Medical Research Council (NHMRC), has been published in two leading journals: Psychiatry Research: Neuroimaging and Depression and Anxiety. Both papers are a result of the same study.
MAPrc Deputy Director Professor Paul Fitzgerald, who led the study, said depression was a common and disabling disorder, affecting up to one in five Australians during their lifetime.
“Electroconvulsive Therapy (ECT) is one of the only established interventions for treatment resistant depression,” Professor Fitzgerald said.
“But use of ECT is limited due to the presence of memory-related side effects and associated stigma.”
For this reason, the MAPrc researchers began exploring new treatment options. MST is a brain-stimulation technique that may have similar clinical effects to ECT without the unwanted side effects.
“In MST, a seizure is induced through the use of magnetic stimulation rather than a direct electrical current like ECT. Magnetic fields are able to pass freely into the brain, making it possible to more precisely focus stimulation,” Professor Fitzgerald said.
“By avoiding the use of direct electrical currents and inducing a more focal stimulation, it is thought that MST will result in an improvement of depressive symptoms without the memory difficulties seen with ECT.”
Research is still at an early stage and MST is only available in a handful of locations worldwide. The MAPrc is the only centre in Australia conducting trials with this therapy.
The study found that MST resulted in an overall significant reduction in depression symptoms; 40 per cent showed overall improvement and 30 per cent showed some improvement. None of the trial participants complained of cognitive side effects.
“MST shows antidepressant efficacy without apparent cognitive side effects. However, substantial research is required to understand the optimal conditions for stimulation and to compare MST to established treatments, including ECT,” Professor Fitzgerald said.
“In order to accurately assess the comparable efficacy of MST to ECT, large-scale randomised controlled trials are required. There remains considerable work to be done before statements of the relative efficacy of these treatments can be made.”
Professor Fitzgerald and his team have received more funding from beyondblue and the NHMRC to carry out a large-scale trial on MST as an alternative treatment for depression.
(Source: monash.edu.au)
New epilepsy gene discovered
In a national research partnership, Dr Sarah Heron from the University of South Australia’s Sansom Research Institute, epilepsy research group, has been working to map the genes responsible for a rare form of epilepsy - autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE).
Dr Heron and her team’s latest research to identify a new gene for this form of epilepsy has been published in Nature Genetics this month.
She says while ADNFLE affects a relatively rare group of people, the symptoms and impact of the condition can be devastating.
“ADNFLE usually develops in childhood and characterised by clusters of seizures during sleep,” Dr Heron says.
“It can have an association with cognitive deficits and or psychiatric comorbidity.
“Our research has identified that mutations in the sodium-gated potassium channel gene KCNT1 cause severe autosomal dominant nocturnal frontal lobe epilepsy and associated intellectual and or psychiatric disability.”
Dr Heron says the identification of the gene has important implications for genetic counselling and also for understanding more about the full spectrum of epilepsy disorders.
Are Schizophrenia and Autism Close Relations?
TAU researcher discovers that family history of schizophrenia is a risk factor for autism
Autism Spectrum Disorders (ASD), a category that includes autism, Asperger Syndrome, and Pervasive Developmental Disorder, are characterized by difficulty with social interaction and communication, or repetitive behaviors. The U.S. Centers for Disease Control and Management says that one in 88 children in the US is somewhere on the Autism spectrum — an alarming ten-fold increase in the last four decades.
New research by Dr. Mark Weiser of Tel Aviv University’s Sackler Faculty of Medicine and the Sheba Medical Center has revealed that ASD appears share a root cause with other mental illnesses, including schizophrenia and bipolar disorder. At first glance, schizophrenia and autism may look like completely different illnesses, he says. But closer inspection reveals many common traits, including social and cognitive dysfunction and a decreased ability to lead normal lives and function in the real world.
Studying extensive databases in Israel and Sweden, the researchers discovered that the two illnesses had a genetic link, representing a heightened risk within families. They found that people who have a schizophrenic sibling are 12 times more likely to have autism than those with no schizophrenia in the family. The presence of bipolar disorder in a sibling showed a similar pattern of association, but to a lesser degree.
A scientific leap forward, this study sheds new light on the genetics of these disorders. The results will help scientists better understand the genetics of mental illness, says Dr. Weiser, and may prove to be a fruitful direction for future research. The findings have been published in the Archives of General Psychiatry.
All in the family
Researchers used three data sets, one in Israel and two in Sweden, to determine the familial connection between schizophrenia and autism. The Israeli database alone, used under the auspices of the ethics committees of both the Sheba Medical Center and the Israeli Defense Forces, included anonymous information about more than a million soldiers, including patients with schizophrenia and ASD.
"We found the same results in all three data sets," he says, noting that the ability to replicate the findings across these extensive databases is what makes this study so significant.Understanding this genetic connection could be a missing link, Dr. Weiser says, and provides a fresh direction for study. The researchers are now taking this research in a clinical direction. For now, though, the findings shouldn’t influence the way that doctors treat patients with either illness, he adds.
(Source: aftau.org)
Perfect Pitch: Knowing the Note May Be in Your Genes
People with perfect pitch seem to possess their own inner pitch pipe, allowing them to sing a specific note without first hearing a reference tone. This skill has long been associated with early and extensive musical training, but new research suggests that perfect pitch may have as much to do with genetics as it does with learning an instrument or studying voice.
Previous research does draw a connection between early musical training and the likelihood of a person developing perfect pitch, which is also referred to as absolute pitch. This is especially true among speakers of tonal languages, such as Mandarin. Speakers of English and other non-tonal languages are far less likely to develop perfect pitch, even if they were exposed to early and extensive musical training.
“We have wondered if perfect pitch is as much about nature or nurture,” said Diana Deutsch, a professor of psychology at the University of California, San Diego. “What is clear is that musically trained individuals who speak a non-tone language can acquire absolute pitch, but it is still a remarkably rare talent. What has been less clear is why most others with equivalent musical training do not.” Deutsch and her colleague Kevin Dooley present their findings at the 164th meeting of the Acoustical Society of America (ASA), held Oct. 22 – 26 in Kansas City, Missouri.
To shine light on this question, the researchers studied 27 English speaking adults, 7 of whom possessed perfect pitch. All began extensive musical training at or before the age of 6. The researchers tested the subjects’ memory ability using a test known as the digit span, which measures how many digits a person can hold in memory and immediately recall in correct order. They presented the digits either visually or auditorily; for the auditory test, the subject listened to the numbers through headphones, and for the visual test the digits were presented successively at the center of a computer screen.
The people with perfect pitch substantially outperformed the others in the audio portion of the test. In contrast, for the visual test, the two groups exhibited very similar performance, and their scores were not significantly different from each other. This is significant because other researchers have shown previously that auditory digit span has a genetic component.
“Our finding therefore shows that perfect pitch is associated with an unusually large memory span for speech sounds,” said Deutsch, “which in turn could facilitate the development of associations between pitches and their spoken languages early in life.”
(Source: newswise.com)
Scientists Build ‘Mechanically Active’ DNA Material That Responds With Movement When Stimulated
Artificial muscles and self-propelled goo may be the stuff of Hollywood fiction, but for UC Santa Barbara scientists Omar Saleh and Deborah Fygenson, the reality of it is not that far away. By blending their areas of expertise, the pair have created a dynamic gel made of DNA that mechanically responds to stimuli in much the same way that cells do.
The results of their research were published online in the Proceedings of the National Academy of Sciences.
"This is a whole new kind of responsive gel, or what some might call a ‘smart’ material," said Saleh, associate professor of materials, affiliated with UCSB’s Biomolecular Science and Engineering program. "The gel has active mechanical capabilities in that it generates forces independently, leading to changes in elasticity or shape, when fed ATP molecules for energy — much like a living cell."
Their DNA gel, at only 10 microns in width, is roughly the size of a eukaryotic cell, the type of cell of which humans are made. The miniscule gel contains within it stiff DNA nanotubes linked together by longer, flexible DNA strands that serve as the substrate for molecular motors.
"DNA gives you a lot more design control," said Fygenson, associate professor of physics and also affiliated with UCSB’s BMSE program. "This system is exciting because we can build nano-scale filaments to specifications." Using DNA design, she said, they can control the stiffness of the nanotubes and the manner and extent of their cross-linking, which will determine how the gel responds to stimuli.
Evolution of new genes captured
Like job-seekers searching for a new position, living things sometimes have to pick up a new skill if they are going to succeed. Researchers from the University of California, Davis, and Uppsala University, Sweden, have shown for the first time how living organisms do this.
The observation, published Oct. 19 in the journal Science, closes an important gap in the theory of natural selection.
Scientists have long wondered how living things evolve new functions from a limited set of genes. One popular explanation is that genes duplicate by accident; the duplicate undergoes mutations and picks up a new function; and, if that new function is useful, the gene spreads.
"It’s an old idea and it’s clear that this happens," said John Roth, a distinguished professor of microbiology at UC Davis and co-author of the paper.
The problem, Roth said, is that it has been hard to imagine how it occurs. Natural selection is relentlessly efficient in removing mutated genes: Genes that are not positively selected are quickly lost.
How then does a newly duplicated gene stick around long enough to pick up a useful new function that would be a target for positive selection?
Experiments in Roth’s laboratory and elsewhere led to a model for the origin of a novel gene by a process of “innovation, amplification and divergence.” This model has now been tested by Joakim Nasvall, Lei Sun and Dan Andersson at Uppsala.
BeerSci: What Beer’s Key Ingredient Reveals About Our Own Genomes
The yeast S. cerevisiae is instrumental in brewing ale. But did you know that it’s also instrumental in helping scientists better understand cells?
Humans have been exploiting S. cerevisiae's fermentation prowess for thousands of years. Without it we wouldn't have beer, bread or wine. In addition to its uses in food production, S. cerevisiae is also an amazing tool for molecular and cell biology, one that is helping scientists suss out the rules of how our cells work and gain clues to what happens at the molecular level when things go wrong.
That’s because S. cerevisiae is one of the simplest eukaryotic cells—cells like those that make up your dog, your houseplants or your local bartender. In fact, in 1996 S. cerevisiae became the first eukaryote to have its genome sequenced. According to the Saccharomyces Genome Database, S. cerevisiae's genome has some 12,100,000 base pairs and some 6,600 open reading frames (that is, places in the genome that could possibly contain a gene).
Most of you, I am sure, remember that there are two general kinds of cells: prokaryotic and eukaryotic. That is, “no nucleus” and “has a nucleus.” That’s all true, but the differences between the two kinds of cells are much more profound than that. Bacteria — prokaryotes — organize their genetic material in a completely different (and much simpler) way than do eukaryotes. Prokaryotes usually only have a chunk of DNA for a genome — usually circular — and a few extra chunks, called plasmids, kicking around in the cytosol. Those plasmids are really useful in doing things like sharing genes between bacteria, and its how one antibiotic-resistant strain of bacteria can pass along antibiotic resistance to a bunch of nigh-unrelated strains of bacteria in, say, your intestines. The genes in bacteria are generally read exactly as they are found in the DNA, kind of like how you’re reading this sentence. No intervening clumps of letters to clutter things up.
Eukaryotes, on the other hand, bundle up all that DNA (and they have a lot of it) into a protein-DNA complex called chromatin, then wind that chromatin into individual chromosomes. Further, the genes are constructed in such a way that they must be heavily processed before they can ever “code” for a functional protein. Much of what we understand about eukaryotic cellular processes and eukaryotic gene expression, we learned by studying the molecular mechanics of S. cerevisiae.
Neuroscientists propose a revolutionary DNA-based approach to map wiring of the whole brain
A team of neuroscientists have proposed a new and potentially revolutionary way of obtaining a neuronal connectivity map (the “connectome”) of the whole brain of the mouse. The details are set forth in an essay published October 23 in the open-access journal PLOS Biology.
The team, led by Professor Anthony Zador, Ph.D., of Cold Spring Harbor Laboratory, aims to provide a comprehensive account of neural connectivity. At present the only method for obtaining this information with high precision relies on examining individual cell-to-cell contacts (synapses) in electron microscopes. But such methods are slow, expensive and labor-intensive.
Zador and colleagues instead propose to exploit high-throughput DNA sequencing to probe the connectivity of neural circuits at the resolution of single neurons.
“Our method renders the connectivity problem in a format in which the data are readable by currently available high-throughput genome sequencing machines,” says Zador. “We propose to do this via a process we’re now developing, called BOINC: the barcoding of individual neuronal connections.”
The proposal comes at a time when a number of scientific teams in the U.S. are progressing in their efforts to map connections in the mammalian brain. These efforts use injections of tracer dyes or viruses to map neuronal connectivity at a “mesoscopic” scale—a mid-range resolution that makes it possible to follow neural fibers between brain regions. Other groups are scaling up approaches based on electron microscopy.
The Fabric for Weaving Memory
The details of memory formation are still largely unknown. It has, however, been established that the two kinds of memory – long term and short term – use different mechanisms. When short-term memory is formed, certain proteins in the nerve cells (neurons) of the brain are transiently modified. To establish long-term memory, the cells have to synthesize new protein molecules. This has been shown in experiments with animals. When drugs were used to block protein synthesis, the treated animals were not able to form long-term memory.
The precise mechanism by which the newly synthesized proteins regulate memory formation is still poorly understood. They are thought to strengthen existing connections between neurons, as well as establish new connections. Both processes are required for long-term memory formation.
A nerve cell in the brain makes connections with tens of thousands of other nerve cells through so-called synapses. When memory is formed, only specific synapses, which are activated by a specific experience are modified. The mechanism of how the synthesis of new proteins can be restricted to these activated synapses has been unclear. Neurobiologists have postulated the existence of “synaptic tags”. One of the candidates is a family of proteins known to regulate local protein synthesis, the CPEB family of proteins. These proteins have been known for some time to perform important tasks during embryonic development, and recently have been identified in neuronal synapses.
In 2007, Krystyna Keleman, a neuroscientist at the Research Institute of Molecular Pathology (IMP) in Vienna, was able to show that fruit flies require CPEB proteins for long-term memory formation.
To study memory formation, the researchers at the IMP looked at the sexual behavior of flies. After copulation, female flies loose interest in the courtship advances of males. Male flies must learn – by trial and error – that only virgin females are receptive. The key to telling them apart is their smell.
Why Some People See Sound
Some people may actually see sounds, say researchers who found this odd ability is possible when the parts of the brain devoted to vision are small.
These findings points to a clever strategy the brain might use when vision is unreliable, investigators added.
Scientists took a closer look at the sound-induced flash illusion. When a single flash is followed by two bleeps, people sometimes also see two illusory consecutive flashes.
Past experiments revealed there are strong differences between individuals when it comes to how prone they are to this illusion. “Some would experience it almost every time a flash was accompanied by two bleeps, others would almost never see the second flash,” said researcher Benjamin de Haas, a neuroscientist at University College London.
These differences suggested to de Haas and his colleagues that maybe variations in brain anatomy were behind who saw the illusion and who did not. To find out, the researchers analyzed the brains of 29 volunteers with magnetic resonance imaging (MRI) and tested them with flashes and bleeps.
On average, the volunteers saw the illusion 62 percent of the time, although some saw it only 2 percent of the time while others saw it 100 percent of the time. They found the smaller a person’s visual cortex was — the part of the brain linked with vision —the more likely he or she experienced the illusion."If we both look at the same thing, we would expect our perception to be identical," de Haas told LiveScience. "Our results demonstrate that this not quite true in every situation — sometimes what you perceive depends on your individual brain anatomy."
The researchers suggest this illusion could reveal a way the brain compensates for imperfect visual circuitry.