Posts tagged science
Articles and news from the latest research reports.
Of noise and neurons: Sensory coding, representation and short-term memory
While much is known about the limiting effect of neural noise on the fidelity of sensory coding representation, knowledge about the impact of noise in short-term memory and integrator networks has remained more elusive. (Integrator networks are networks of nodes – in this case neurons in a biological network – often recurrently connected, whose time dynamics settle to stable stationary, cyclic, or chaotic patterns, that can integrate or store memories of external inputs.)
Recently, however, scientists at The Hebrew University of Jerusalem, Harvard University and University of Texas, Austin used statistical and dynamical approaches to investigate how neural noise interacts with neural and network parameters to limit memory. They derived a series of unanticipated results – including the implications that short-term memory may be co-localized with sensory representation – by establishing a fundamental limit on the network’s ability to maintain a persistent neural state.
Foggy perception slows us down
Fog is an atmospheric phenomenon that afflicts millions of drivers every day, impairing visibility and increasing the risk of an accident. The ways people respond to conditions of reduced visibility is a central topic in vision research. It has been shown that people tend to underestimate speeds when visibility is reduced equally at all distances, as for example, when driving with a uniformly fogged windshield. But what happens when the visibility decreases as you look further into the distance, as happens when driving in true fog? New research by Paolo Pretto at the Max Planck Institute for Biological Cybernetics in Tübingen published in eLife, reveals that people tend to overestimate their speed when driving in fog-like conditions and therefore naturally tend to drive at a slower pace.
New Study Shows Effects of Prehistoric Nocturnal Life on Mammalian Vision
Since the age of dinosaurs, most species of day-active mammals have retained the imprint of nocturnal life in their eye structures. Humans and other anthropoid primates, such as monkeys and apes, are the only groups that deviate from this pattern, according to a new study from The University of Texas at Austin and Midwestern University.
The findings, published in a forthcoming issue of Proceedings of the Royal Society B, are the first to provide a large-scale body of evidence for the “nocturnal bottleneck theory,” which suggests that mammalian sensory traits have been profoundly influenced by an extended period of adaptation to nocturnality during the Mesozoic Era. This period lasted from 250 million years ago to 65 million years ago.
To survive in the night, mammals had a host of visual capabilities, such as good color vision and high acuity, which were lost as they passed through the nocturnal “bottleneck.”
Single protein targeted as the root biological cause of several childhood psychiatric disorders
New research in The FASEB Journal suggests that dysfunction in the SRGAP3 protein may lead to schizophrenia, hydrocephalus, mental retardation and some forms of autism in childhood
A new research discovery has the potential to revolutionize the biological understanding of some childhood psychiatric disorders. Specifically, scientists have found that when a single protein involved in brain development, called “SRGAP3,” is malformed, it causes problems in the brain functioning of mice that cause symptoms that are similar to some mental health and neurological disorders in children. Because this protein has similar functions in humans, it may represent a “missing link” for several disorders that are part of an illness spectrum. In addition, it offers researchers a new target for the development of treatments that can correct the biological cause rather than treat the symptoms. This discovery was published in November 2012 print issue of The FASEB Journal.
"Developmental brain disorders such as schizophrenia, hydrocephalus, mental retardation and autism are among the most devastating diseases in children and young adults," said Dusan Bartsch, Ph.D., a researcher involved in the work from the Department of Molecular Biology at the Central Institute of Mental Health at the University of Heidelberg in Mannheim, Germany. "We hope that our findings will contribute to a better understanding, and in the end, to better treatments for these disorders."
Bartsch and colleagues made this discovery using mice with the SRGAP3 protein inactivated. Then they conducted several experiments comparing these mice to normal mice. The mice with inactive SRGAP3 showed clear changes in their brains’ anatomy, which resulted in altered behavior similar to certain symptoms in human neurological and psychiatric diseases. An involvement of SRGAP3 in different brain disorders could indicate that these disorders are possibly connected, as SRGAP3 is a key player in brain development. These different disorders could be connected via the SRGAP3 protein because they all emerge from disturbed development of the nervous system.
"Since Freud put biological psychiatry on the map, we’ve slowly increased our understanding of how mental health is dictated by chemistry," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "Eventually we’ll understand the complex biology underlying most psychiatric illnesses, from genes to proteins to cell signaling to overt behaviors. Along the way, as in this report, we’re likely to find single targets close to the roots of apparently different mental illnesses."
(Source: eurekalert.org)
Causation Warps Our Perception of Time
You push a button to call the elevator to your floor and you wait for what seems like forever, thinking it must be broken. When your friend pushes the button, the elevator appears within 10 seconds. “She must have the magic touch,” you say to yourself. This episode reflects what philosophers and psychological scientists call “temporal binding”: Events that occur close to one another in time and space are sometimes “bound” together and we perceive them as meaningful episodes.
New research published in Psychological Science, a journal of the Association for Psychological Science, suggests that binding may reveal important insights into how we experience time.
Research has shown that our perceptual system seems to pull causally-related events together – compared to two events that are thought to happen of their own accord, we perceive the first event as occurring later if we think it is the cause and we perceive the second event as occurring earlier if we think it is the outcome.
So how does this temporal binding occur?
Some researchers have hypothesized that our perceptual system binds events together if we perceive them to be the result of intentional action, and that temporal binding results from our ability to link our actions to their consequences. But psychological scientist Marc Buehner of Cardiff University, UK wondered whether temporal binding might be rooted in a more general capacity to understand causal relations.
“We already know that people are more likely to infer a causal relation if two things are close in time. It follows, via Bayesian calculus, that the reverse should also be true: If people know two things are causally related, they should expect them to be close in time,” Buehner says. “Time perception is inherently uncertain, so it makes sense for systematic biases in the form of temporal binding to kick in. If this is true, then it would suggest that temporal binding is a general phenomenon of which intentional action is just a special case.”
OHSU researchers discover how enzyme may prevent nervous system repair in multiple sclerosis
Discovery could be ‘life-changer’ for millions with MS, stroke and other conditions that cause brain damage
Researchers at Oregon Health & Science University have discovered that blocking a certain enzyme in the brain can help repair the brain damage associated with multiple sclerosis and a range of other neurological disorders.
The discovery could have major implications for multiple sclerosis, complications from premature birth and other disorders and diseases caused by demyelination – a process where the insulation-like sheath surrounding nerve cells in the brain becomes damaged or destroyed. Demyelination disrupts the ability of nerve cells to communicate with each other, and produces a range of motor, sensory and cognitive problems in MS and other disorders.
The study was published this week in the online edition of the Annals of Neurology. The study was conducted by a team of researchers led by Larry Sherman, Ph.D., who is a professor of cell and development biology at OHSU and a senior scientist in the Division of Neuroscience at the Oregon National Primate Research Center.
"What this means is that we have identified a whole new target for drugs that might promote repair of the damaged brain in any disorder in which demyelination occurs," Sherman said. "Any kind of therapy that can promote remyelination could be an absolute life-changer for the millions of people suffering from MS and other related disorders."
New MS drug proves effective where others have failed
A drug which ‘reboots’ a person’s immune system has been shown to be an effective treatment for multiple sclerosis (MS) patients who have already failed to respond to the first drug with which they were treated (a ‘first-line’ therapy), as well as affected individuals who were previously untreated. The results of these two phase III clinical trials were published today in the journal The Lancet.
The new studies, sponsored by Genzyme (a Sanofi company) and Bayer Schering Pharma, showed that alemtuzumab significantly reduces the number of attacks (or relapses) experienced by people with MS compared to interferon beta-1a (known commercially as Rebif). This was seen both in patients who had not previously received any treatment (drug-naïve) and those who have continued to show disease activity whilst taking an existing treatment for MS.
High blood pressure damages the brain in early middle age
Uncontrolled high blood pressure damages the brain’s structure and function as early as young middle-age, and even the brains of middle-aged people who clinically would not be considered to have hypertension have evidence of silent structural brain damage, a study led by researchers at UC Davis has found.
The investigation found accelerated brain aging among hypertensive and prehypertensive individuals in their 40s, including damage to the structural integrity of the brain’s white matter and the volume of its gray matter, suggesting that vascular brain injury “develops insidiously over the lifetime with discernible effects.”
The study is the first to demonstrate that there is structural damage to the brains of adults in young middle age as a result of high blood pressure, the authors said. Structural damage to the brain’s white matter caused by high blood pressure previously has been associated with cognitive decline in older individuals.
Published online today in the medical journal The Lancet Neurology, the study will appear in print in the December 2012 issue. It emphasizes the need for lifelong attention to vascular risk factors for brain aging, said study senior author Charles DeCarli, professor of neurology and director of the UC Davis Alzheimer’s Disease Center.
Global Genome Effort Seeks Genetic Roots of Disease
By decoding the genomes of more than 1,000 people whose homelands stretch from Africa and Asia to Europe and the Americas, scientists have compiled the largest and most detailed catalog yet of human genetic variation. The massive resource will help medical researchers find the genetic roots of rare and common diseases in populations worldwide.
The 1000 Genomes Project involved some 200 scientists at Washington University School of Medicine in St. Louis and other institutions. Results detailing the DNA variations of individuals from 14 ethnic groups are published Oct. 31 in the journal Nature. Eventually, the initiative will involve 2,500 individuals from 26 populations.
“With this resource, researchers have a roadmap to search for the genetic origins of diseases in populations around the globe,” says one of the study’s co-principal investigators, Elaine Mardis, PhD, co-director of The Genome Institute at Washington University. “We estimate that each person carries up to several hundred rare DNA variants that could potentially contribute to disease. Now, scientists can investigate how detrimental particular rare variants are in different ethnic groups.”
When people worry about math, the brain feels the pain
Mathematics anxiety can prompt a response in the brain similar to when a person experiences physical pain, according to new research at the University of Chicago.
Using brain scans, scholars determined that the brain areas active when highly math-anxious people prepare to do math overlap with the same brain areas that register the threat of bodily harm—and in some cases, physical pain.
“For someone who has math anxiety, the anticipation of doing math prompts a similar brain reaction as when they experience pain—say, burning one’s hand on a hot stove,” said Sian Beilock, professor of psychology at the University of Chicago and a leading expert on math anxiety.
Surprisingly, the researchers found it was the anticipation of having to do math, and not actually doing math itself, that looked like pain in the brain. “The brain activation does not happen during math performance, suggesting that it is not the math itself that hurts; rather the anticipation of math is painful,” added Ian Lyons, a 2012 PhD graduate in psychology from UChicago and a postdoctoral scholar at Western University in Ontario, Canada.
The two report their findings in a paper, “When Math Hurts: Math Anxiety Predicts Pain Network Activation in Anticipation of Doing Math,” in the current issue of PLOS One.