Posts tagged brain
Articles and news from the latest research reports.
Scientists have discovered the first direct evidence that a biological mechanism long suspected in epilepsy is capable of triggering the brain seizures – opening the door for studies to seek improved treatments or even preventative therapies.
Researchers at Cincinnati Children’s Hospital Medical Center report Sept. 19 in Neuron that molecular disruptions in small neurons called granule cells – located in the dentate gyrus region of the brain – caused brain seizures in mice similar to those seen in human temporal lobe epilepsy. The dentate gyrus is in the hippocampus of the temporal lobe, and temporal lobe epilepsy is one of the most common forms of the disorder.
“Epilepsy is one of those rare disorders where we have no real preventative therapies, and current treatments after diagnosis can have significant side effects,” said Steven Danzer, PhD, principal investigator on the study and a neuroscientist in the Department of Anesthesia at Cincinnati Children’s. “Establishing which cells and mechanisms are responsible for the seizures allows us to begin working on ways to control or eliminate the problem therapeutically, and in a more precise manner.”
When women are aroused, they overlook certain “disgust elicitors” associated with sex, enabling them to go ahead with the deed, according to a paper published by Dutch clinical psychologists.
According to the study, published in the journal PLoS, humans have somehow managed to strike a successful balance between two important evolutionary functions — sex and disgust. The latter is considered by some psychologists to be a natural defence mechanism against disease — other people’s mouths, for instance, pose a higher risk of contamination and are therefore considered an external threat perceived as highly disgusting. When it comes to the nitty gritty of sex, there are plenty of “disgust elicitors” that we relate to contamination says the paper, namely saliva, sweat and semen.
In making this link, the paper’s authors’ decided to tackle a rather interesting question: how do people have pleasurable sex at all?
The eyes may be windows into the soul, but following their movement also could allow doctors to make quick, accurate diagnoses for disorders like autism, schizophrenia, or attention deficit hyperactivity disorder, various research projects suggest.
Eye tracking, which records where subjects focus when watching visual displays, could diagnose brain disorders more accurately than subjective questionnaires or medical examinations do, researchers say. Exams are expensive and time-consuming, and subjective tests have been known to wrongly identify healthy people or misdiagnose disorders.
To make sense of all that people see, the brain filters huge amounts of visual information, fills in gaps and focuses on certain objects. That complex task uses many mental circuits, so differences in what people choose to look at ― differences so subtle that only a computer can spot them ― could provide unprecedented insight into common neurological problems.
I’ve been up since 6 am. I’ve had a breath test for alcohol, a urine test for drugs and a psychological test for mental health. Then I’m handed a red pill and a glass of water. I swallow it… and I’m told to relax. Which is easier said than done when you don’t know if you’ve just taken vitamin C or 83 milligrams of pure MDMA.
I’m taking part in a groundbreaking study on MDMA, the drug commonly known as ecstasy. The research is run by David Nutt of Imperial College London, a former government adviser and one of the few UK researchers licensed to study class-A drugs.
His main aim is to discover what MDMA does to the human brain, something that, remarkably, has never been done before. A second goal is to study MDMA as a therapy for post-traumatic stress disorder. The experiment is also being filmed for a Channel 4 documentary called Drugs Live: The Ecstasy Trial, which will be broadcast in the UK next week.
Delirium has a dramatic impact on older people but is frequently undiagnosed
Delirium is widespread among older people but often goes ignored and untreated, according to new research by US and UK researchers including the University of East Anglia.
Published in the September issue of the Journal of Hospital Medicine, the findings show that delirium - or acute confusion – is common among older adults in hospitals and nursing homes. It has a negative impact on cognition and independence, significantly increases the risk of developing dementia, and triples the likelihood of death. Yet this common, acute condition is frequently either undiagnosed or accepted as inevitable.
Led by the Regenstrief Institute and Indiana University, the research team reviewed 45 years of research encompassing 585 studies. They found that one in three cases of delirium were preventable and are calling for delirium to be identified and treated early to prevent poor long-term prognosis.
“As a geriatric psychiatrist I have seen that around 50 per cent or people with dementia in hospital develop delirium,” said co-author Dr Chris Fox, of Norwich Medical School at the University of East Anglia.
“This is because in addition to having dementia, they have multiple risk factors that can predispose and precipitate delirium – including serious illnesses and pre-existing cognitive impairment. In addition, hospital staff commonly label the signs as dementia related and do not pick up the delirium.”
“We need to develop better mechanisms for diagnosing delirium so that prompt treatment regimes can be initiated.”
In general patient groups, more than 60 per cent of delirium cases are not recognised or treated, and significant numbers of elderly patients leave hospital with ongoing delirium which has been missed.
The authors, led by Dr Babar Khan of the Regenstrief Institute and Indiana University School of Medicine, said that delirium could be prevented by eliminating restraints, treating depression, ensuring that patients have access to glasses and hearing aids, and prescribing classes of antipsychotics that do not negatively affect the aging brain. They also noted the need for a more sensitive screening tool for delirium, especially when administered by a non-expert.
“Delirium is extremely common among older adults in intensive care units and is not uncommon in other hospital units and in nursing homes, but too often it is ignored or accepted as inevitable,” said Dr Khan. “Delirium significantly increases risk of developing dementia and triples likelihood of death. It cannot be ignored.”
Co-author Dr Malaz Boustani, of the Regenstrief Institute, Indiana University School of Medicine and Wishard Healthy Aging Brain Center, said: “Having delirium prolongs the length of a hospital stay, increases the risk of post-hospitalization transfer to a nursing home, increases the risk of death and may lead to permanent brain damage.”
(Source: uea.ac.uk)
The absence of a specific type of neuron in the brain can lead to obesity and diabetes in mice report researchers in The EMBO Journal. The outcome, however, depends on the type of diet that the animals are fed.
A lack of AgRP-neurons, brain cells known to be involved in the control of food intake, leads to obesity if mice are fed a regular carbohydrate diet. However, animals that are deficient in AgRP-neurons but which are raised on a high-fat diet are leaner and healthier. The differences are due to the influence of the AgRP-neurons on the way other tissues in the body break down and store nutrients. Mice lacking AgRP-neurons adapt poorly to a carbohydrate diet and their metabolism seems better suited for feeding on fat.
The scientists wanted to show if a primary setting in the brain might directly affect the relative balance that exists in peripheral tissue between storage, conversion and utilization of carbohydrate and lipids. “The idea that we wanted to test in our experiments was whether the action of a specific type of brain cell known as the AgRP-neuron extended beyond its known influence on food intake. We found a new function for these cells, one that affects the communication with and activities of other tissues in the body including the liver, muscle and the pancreas,” added Luquet.
The researchers showed that mice that lacked AgRP-neurons from birth and which were fed on a regular carbohydrate diet had excessive body fat, increased amounts of the sugar-regulating hormone insulin, and normal levels of glucose in the blood. When the same animals were fed a high fat diet they showed a reduced gain in body weight and improved glucose clearance in the blood.
Theory: Music underlies language acquisition
Contrary to the prevailing theories that music and language are cognitively separate or that music is a byproduct of language, theorists at Rice University’s Shepherd School of Music and the University of Maryland, College Park (UMCP) advocate that music underlies the ability to acquire language.
“Spoken language is a special type of music,” said Anthony Brandt, co-author of a theory paper published online this month in the journal Frontiers in Cognitive Auditory Neuroscience. “Language is typically viewed as fundamental to human intelligence, and music is often treated as being dependent on or derived from language. But from a developmental perspective, we argue that music comes first and language arises from music.”
Brandt, associate professor of composition and theory at the Shepherd School, co-authored the paper with Shepherd School graduate student Molly Gebrian and L. Robert Slevc, UMCP assistant professor of psychology and director of the Language and Music Cognition Lab.
“Infants listen first to sounds of language and only later to its meaning,” Brandt said. He noted that newborns’ extensive abilities in different aspects of speech perception depend on the discrimination of the sounds of language – “the most musical aspects of speech.”
The paper cites various studies that show what the newborn brain is capable of, such as the ability to distinguish the phonemes, or basic distinctive units of speech sound, and such attributes as pitch, rhythm and timbre.
The authors define music as “creative play with sound.” They said the term “music” implies an attention to the acoustic features of sound irrespective of any referential function. As adults, people focus primarily on the meaning of speech. But babies begin by hearing language as “an intentional and often repetitive vocal performance,” Brandt said. “They listen to it not only for its emotional content but also for its rhythmic and phonemic patterns and consistencies. The meaning of words comes later.”
Brandt and his co-authors challenge the prevailing view that music cognition matures more slowly than language cognition and is more difficult. “We show that music and language develop along similar time lines,” he said.
Infants initially don’t distinguish well between their native language and all the languages of the world, Brandt said. Throughout the first year of life, they gradually hone in on their native language. Similarly, infants initially don’t distinguish well between their native musical traditions and those of other cultures; they start to hone in on their own musical culture at the same time that they hone in on their native language, he said.
The paper explores many connections between listening to speech and music. For example, recognizing the sound of different consonants requires rapid processing in the temporal lobe of the brain. Similarly, recognizing the timbre of different instruments requires temporal processing at the same speed — a feature of musical hearing that has often been overlooked, Brandt said.
“You can’t distinguish between a piano and a trumpet if you can’t process what you’re hearing at the same speed that you listen for the difference between ‘ba’ and ‘da,’” he said. “In this and many other ways, listening to music and speech overlap.” The authors argue that from a musical perspective, speech is a concert of phonemes and syllables.
“While music and language may be cognitively and neurally distinct in adults, we suggest that language is simply a subset of music from a child’s view,” Brandt said. “We conclude that music merits a central place in our understanding of human development.”
Brandt said more research on this topic might lead to a better understanding of why music therapy is helpful for people with reading and speech disorders. People with dyslexia often have problems with the performance of musical rhythm. “A lot of people with language deficits also have musical deficits,” Brandt said.
More research could also shed light on rehabilitation for people who have suffered a stroke. “Music helps them reacquire language, because that may be how they acquired language in the first place,” Brandt said.
(Source: news.rice.edu)
Although images in textbooks generally represent phylogenetic trees with trunks angling up and to the right, research shows that students have better comprehension when the trunks angle down to the right.
New Findings on Protein Misfolding
Misfolded proteins can cause various neurodegenerative diseases such as spinocerebellar ataxias (SCAs) or Huntington’s disease, which are characterized by a progressive loss of neurons in the brain. Researchers of the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch, Germany, together with their colleagues of the Université Paris Diderot, Paris, France, have now identified 21 proteins that specifically bind to a protein called ataxin-1. Twelve of these proteins enhance the misfolding of ataxin-1 and thus promote the formation of harmful protein aggregate structures, whereas nine of them prevent the misfolding (PLoS Genetics).
Proteins only function properly when the chains of amino acids, from which they are built, fold correctly. Misfolded proteins can be toxic for the cells and assemble into insoluble aggregates together with other proteins. Ataxin-1, the protein that the researchers have now investigated, is very prone to misfolding due to inherited gene defects that cause neurodegenerative diseases. The reason for this is that the amino acid glutamine is repeated in the amino acid chain of ataxin-1 very often - the more glutamine, the more toxic the protein. Approximately 40 repeats of glutamine are considered to be toxic for the cells.
Now, Dr. Spyros Petrakis, Dr. Miguel Andrade, Professor Erich Wanker and colleagues have identified 21 proteins that mainly interact with ataxin-1 and influence its folding or misfolding. Twelve of these proteins enhance the toxicity of ataxin-1 for the nerve cells, whereas nine of the identified proteins reduce its toxicity.
Furthermore, the researchers detected a common feature in the structure of those proteins that enhances toxicity and aggregation. It is a special structure scientists call “coiled-coil-domain” because it resembles a double twisted spiral or helix. Apparently this structure promotes aggregation, because proteins that interact with ataxin-1 and have this domain enhance the toxic effect of mutated ataxin-1. As the researchers said, this structure could be a potential target for therapy: “A careful analysis of the molecular details could help to discover drugs that suppress toxic processes.”
(Source: mdc-berlin.de)
Confirming earlier scientific doubts, a new study concludes that chronic fatigue syndrome is not caused by two viruses known as XMRV and pMLV.
Researchers from the U.S. National Institutes of Health, the U.S. Centers for Disease Control and Prevention, Columbia University and other institutions, including some scientists who did the original research, examined 147 patients with chronic fatigue syndrome from sites across the country and compared them to 146 healthy patients.
Bottom line? “This analysis reveals no evidence of either XMRV or pMLV infection,” the authors wrote. The study is published in the September/October issue of the journal mBio.