Posts tagged brain
Articles and news from the latest research reports.
New Treatment for ‘Sleeping Beauty’ Syndrome?
Most of us have experienced it: that dull, dragging semi-conscious state of deadened awareness and desperate urge to nap that comes from sleep deprivation. For people with primary hypersomnia, however, this is the way they go through life, constantly feeling only half-awake but never able to get enough good sleep to arise truly refreshed. Also known as “Sleeping Beauty Syndrome,” the condition leaves those with the worst cases languishing in bed in what seems like the opposite of a fairy tale, without a prince’s kiss to cure them.
But a new study, published in Science Translational Medicine, suggests both a possible cause and a potential treatment for the condition, which may ultimately lead to treatments for other sleep disorders. The origin of primary hypersomnia, which has some genetic components is still unknown, as is the number of people who are affected by it.
One particularly striking form of the disease, Kleine-Levin syndrome, produces such tiredness and sleep-drunkenness that people are unable to attend school or work. In males, it can include hypersexual behavior, compulsive masturbation, a desire for promiscuous sex or making inappropriate sexual advances, all while in a sleepy, semi-conscious state.
In the latest study, researchers led by David Rye of Emory University in Atlanta studied 10 men and 22 women seeking treatment for primary hypersomnia. In the patients’ spinal fluid, the scientists discovered a previously uncharacterized chemical that stimulates the GABA-A receptor. This receptor is best known as the site where sleep-inducing drugs like Valium and Xanax have their effects, since activating GABA-A receptors can result in drowsiness.
The finding suggested a possible treatment. A drug, known as flumanezil can treat Valium and Xanax overdoses or to reverse the effects of related compounds used in anesthesia. Could it block or reverse the effects of the unknown agent that was activating GABA-A receptors in primary hypersomnia?
The authors conducted a brief placebo controlled trial with seven patients—including one with Kleine-Levin symptoms — to find out. Indeed, injections of flumanezil improved the participants’ ability to pay attention and remain alert. One participant has now taken the drug daily for four years. “Although her nightly sleep duration remained at 9 to 10 hours, she nearly always awakened refreshed without an alarm and daytime sleepiness was markedly reduced,” the researchers write.
… and does Google and Wikipedia make it better or worse? Studies show that other people and tools influence our brain power as much as our own minds.
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Research shows that people don’t tend to rely on their memories for things they can easily access. Things like the world in front of our eyes, for example, can be changed quite radically without people noticing. Experiments have shown that buildings can somehow disappear from pictures we’re looking at, or the people we’re talking to can be switched with someone else, and often we won’t notice – a phenomenon called “change blindness”. This isn’t as an example of human stupidity – far from it, in fact – this is an example of mental efficiency. The mind relies on the world as a better record than memory, and usually that’s a good assumption.
As a result, philosophers have suggested that the mind is designed to spread itself out over the environment. So much so that, they suggest, the thinking is really happening in the environment as much as it is happening in our brains. The philosopher Andy Clark called humans “natural born cyborgs”, beings with minds that naturally incorporate new tools, ideas and abilities. From Clark’s perspective, the route to a solution is not the issue – having the right tools really does mean you know the answers, just as much as already knowing the answer.
Relating the function of neuronal cell types to information processing and behavior is a central goal of neuroscience. In the hippocampus, pyramidal cells in CA1 and the subiculum process sensory and motor cues to form a cognitive map encoding spatial, contextual, and emotional information, which they transmit throughout the brain. Do these cells constitute a single class or are there multiple cell types with specialized functions? Using unbiased cluster analysis, we show that there are two morphologically and electrophysiologically distinct principal cell types that carry hippocampal output. We show further that these two cell types are inversely modulated by the synergistic action of glutamate and acetylcholine acting on metabotropic receptors that are central to hippocampal function. Combined with prior connectivity studies, our results support a model of hippocampal processing in which the two pyramidal cell types are predominantly segregated into two parallel pathways that process distinct modalities of information.
The man whose brain ignores one half of his world
Alan Burgess doesn’t need a rhyme to remember the 5th of November. He’ll never forget the day he had his stroke. It left him with a syndrome known as hemispatial neglect and a strange new perspective.
I asked him how he explains this to other people. “I say it’s two different worlds,” says Burgess. “My old world finished on 5 November 2007 and the new world started the same day.”
His stroke damaged the parietal lobe on the right side of his brain, the part that deals with the higher processing of attention. The damage causes him to ignore people, sounds, and objects on his left.
"Hemispatial neglect typically occurs after a stroke," says Dr Paresh Malhotra, senior lecturer in neurology at Imperial College London. "It is not blindness in one eye, and it’s not damage to the primary sensory cortex, it’s a process of ignoring, for want of a better word, one side of space."
(Image credit: zeably.com)
Scientists report a potential new treatment to prevent strokes
Scientists may have discovered a new way to prevent strokes in high risk patients, according to research from the University of Warwick and University Hospitals Coventry and Warwickshire (UHCW).
Work by a new research group, led by Professor Donald Singer, Professor of Therapeutics at Warwick Medical School and Professor Chris Imray from UHCW, has now been published in US journal Stroke.
The group is using ultrasound scanning to look at patients with carotid artery disease, one of the major causes of stroke. Clots can form on diseased carotid arteries in the neck. Small parts of these clots can released to form microemboli, which can travel to block key brain arteries and lead to weakness, disturbed speech, loss of vision and other serious stroke syndromes. Standard anti-platelet drugs such as aspirin may not prevent the formation of harmful microemboli.
The scanning process can be used to find patients at very high risk of stroke because microemboli have formed despite prior anti-platelet drugs. Using scanning, the team has found that tirofiban, another anti-platelet drug designed to inhibit the formation of blood clots, can suppress microemboli where previous treatment such as aspirin has been ineffective. In their study, tirofiban was more effective than other ‘rescue’ treatment.
Professor Singer said: “These findings show that the choice of rescue medicine is very important when carotid patients develop microemboli despite previous treatment with powerful anti-platelet drugs such as aspirin. We now need to go on to further studies of anti-microemboli rescue treatments, to aim for the right balance between protection and risk for our patients.”
Professor Imray said: “These findings show the importance of ultrasound testing for micro-emboli in carotid disease patients. These biomarkers of high stroke risk cannot be predicted just from assessing the severity of risk factors such as smoking history, cholesterol and blood pressure.”
Scientists solve birth and migration mysteries of cortex’s powerful inhibitors, ‘chandelier’ cells
The cerebral cortex of the human brain has been called “the crowning achievement of evolution.” Ironically, it is so complex that even our greatest minds and most sophisticated science are only now beginning to understand how it organizes itself in early development, and how its many cell types function together as circuits.
A major step toward this great goal in neuroscience has been taken by a team led by Professor Z. Josh Huang, Ph.D., at Cold Spring Harbor Laboratory (CSHL). Today they publish research for the first time revealing the birth timing and embryonic origin of a critical class of inhibitory brain cells called chandelier cells, and tracing the specific paths they take during early development into the cerebral cortex of the mouse brain.
These temporal and spatial sequences are regarded by Huang as genetically programmed aspects of brain development, accounting for aspects of the brain that are likely identical in every member of a given species, including humans. Exceptions to these stereotypical patterns include irregularities caused by gene mutations or protein malfunctions, both of which are now being identified in people with developmental disorders and neuropsychiatric illnesses.
Chandelier cells were first noticed only 40 years ago, and in the intervening years frustratingly little has been learned about them, beyond the fact that they “hang” individually among great crowds of excitatory cells in the cortex called pyramidal neurons, and that their relatively short branches make contact with these excitatory cells. Indeed, a single chandelier cell connects, or “synapses,” with as many as 500 pyramidal neurons. Noting this, the great biologist Francis Crick decades ago speculated that chandelier cells exerted some kind of “veto” power over the messages being exchanged by the much more numerous excitatory cells in their vicinity.
Forget All-Night Studying, a Good Night’s Sleep Is Key to Doing Well on Exams
As fall semesters wind down at the country’s colleges and universities, students will be pulling all-night study sessions to prepare for final exams. Ironically, the loss of sleep during these all-nighters could actually work against them performing well, says a Harris Health System sleep specialist.
Dr. Philip Alapat, medical director, Harris Health Sleep Disorders Center, and assistant professor, Baylor College of Medicine, recommends students instead study throughout the semester, set up study sessions in the evening (the optimal time of alertness and concentration) and get at least 8 hours of sleep the night before exams.
“Memory recall and ability to maintain concentration are much improved when an individual is rested,” he says. “By preparing early and being able to better recall what you have studied, your ability to perform well on exams is increased.”
Alapat’s recommendations:
• Get 8-9 hours of sleep nightly (especially before final exams)• Try to study during periods of optimal brain function (usually around 6-8 p.m.)
• Avoid studying in early afternoons, usually the time of least alertness
• Don’t overuse caffeinated drinks (caffeine remains in one’s system for 6-8 hours)
• Recognize that chronic sleep deprivation may contribute to development of long-term diseases like diabetes, high blood pressure and heart disease
If suffering from bouts of chronic sleep deprivation or nightly insomnia that lasts for more than a few weeks, Alapat suggests consulting a sleep specialist.
A step forward in regenerating and repairing damaged nerve cells
A team of IRCM researchers, led by Dr. Frédéric Charron, recently uncovered a nerve cell’s internal clock, used during embryonic development. The discovery was made in collaboration with Dr. Alyson Fournier’s laboratory at the Montreal Neurological Institute. Published in the prestigious scientific journal Neuron, this breakthrough could lead to the development of new tools to repair and regenerate nerve cells following injuries to the central nervous system.
Researchers in Dr. Charron’s laboratory study neurons, which are the nerve cells that make up the central nervous system (brain and spinal cord). They want to better understand how neurons navigate through the developing embryo to arrive at their correct destination.
“To properly form neural circuits, developing axons (long extensions of neurons that form nerves) follow external signals to reach the right targets,” says Dr. Frédéric Charron, Director of the Molecular Biology of Neural Development research unit at the IRCM. “We discovered that nerve cells also have an internal clock, which changes their response to external signals as they develop over time.”
For this research project, IRCM scientists focused on the Sonic Hedgehog (Shh) protein, which gives cells important information for the embryo to develop properly and plays a critical role in the development of the central nervous system.
“It is known that axons follow the Shh signal during their development,” explains Dr. Patricia Yam, research associate in Dr. Charron’s laboratory and first author of the study. “However, axons change their behaviour once they reach this protein, and this has been a mystery for the scientific community. We found that a nerve cell’s internal clock switches its response to external signals when it reaches the Shh protein, at which time it becomes repelled by the Shh signal rather than following it.”
“Our findings therefore showed that more than one system is involved in directing axon pathfinding during development,” adds Dr. Yam. “Not only do nerve cells respond to external signals, but they also have an internal control system. This discovery is important because it offers new possibilities for developing techniques to regenerate and repair damaged nerve cells. Along with trying to modify external factors, we can now also consider modifying elements inside a cell in order to change its behaviour.”
The Future of Memory: Remembering, Imagining, and the Brain
During the past few years, there has been a dramatic increase in research examining the role of memory in imagination and future thinking. This work has revealed striking similarities between remembering the past and imagining or simulating the future, including the finding that a common brain network underlies both memory and imagination. Here, we discuss a number of key points that have emerged during recent years, focusing in particular on the importance of distinguishing between temporal and nontemporal factors in analyses of memory and imagination, the nature of differences between remembering the past and imagining the future, the identification of component processes that comprise the default network supporting memory-based simulations, and the finding that this network can couple flexibly with other networks to support complex goal-directed simulations. This growing area of research has broadened our conception of memory by highlighting the many ways in which memory supports adaptive functioning.
Glowing Vulcan ears reveal brain’s lost neurons
These glowing shapes aren’t the ears of a rave-happy Vulcan - they’re slices from a mouse’s brain.
The slice on the right is from a mouse that lacks a gene called Arl13b - the same gene whose mutation causes Joubert syndrome in humans. This is a rare neurological condition that is linked with autism-spectrum disorders and brain structure malformations.
Without Arl13b, the nerve cells known as interneurons can’t find the right destination in the cerebral cortex during the brain’s development. Since the interneurons don’t end up in the right places, they can’t be wired up properly later on. This causes the disrupted brain development, typical of Joubert syndrome, visible in the image on the right.
The researchers hope that their findings will lead to better treatments for people who have the syndrome.
"Ultimately, if you’re going to come up with therapeutic solutions, it’s important to understand the biology of the disease," says Eva Anton of the University of North Carolina in Chapel Hill, who worked on the research, which was published in Developmental Cell last week.