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."
Read more
(Image credit: zeably.com)
Filed under brain hemiagnosia hemispatial neglect stroke visual perception psychology neuroscience science
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.”
Filed under brain stroke carotid artery disease microemboli ultrasound science
Researchers at Yale University have found that neural receptors in a fly’s antenna are able to communicate with one another despite a lack of synaptic connections. They suggest in their paper published in the journal Nature that the communication between the neurons occurs via electrical signals transported by shared fluids.
Suspecting that the fluid filled hairs in the antennas of the fly, Drosophila melanogaster, called sensilla, might possess a property known as ephaptic coupling, where nerve cells communicate without a direct link, the researchers tested the abilities of several fly specimens in their lab. The first focused on two receptors located in the sensilla responsible for detecting fruity methyl hexanoate and banana-scented 2-heptanone, respectively. When exposed to methyl hexonate, they found that only the first receptor fired. If heptanone were suddenly introduced however, the first receptor ceased firing immediately as the second commenced indicating that some form of communication between the two was occurring. They found that the reverse worked as well. To rule out possible modes of communication, the researchers conducted the same experiment with flies that had their synapses disabled via drugs and with others that had had their antennas physically cut off. Both showed the same results indicating that the communication was not direct but was localized.
In another experiment the researchers blocked a neuron in a sensilla responsible for detecting vinegar which was situated next to a neuron responsible for detecting carbon dioxide (for avoidance). When placed in a maze with two arms that smelled of carbon dioxide and one of vinegar, the fly headed for the vinegar scented arm, showing that the vinegar disabled neuron was still able to communicate with its carbon dioxide detecting partner.
The researchers suggest such an ability in flies might help in figuring out which path to take when encountering an environment filled with many different options. They also suggest that neuron pairs in the sensilla might be communicating with one another via electrical signals. When one detects what it’s supposed to detect, it sends a small charge into the fluid in which it and other neurons reside. That charge may then cause other neurons in the vicinity to go silent.
(Source: medicalxpress.com)
Filed under nerve cells neuron synapses neural receptors drosophila neuroscience science
Why older people struggle to read fine print
Psychologists from the University of Leicester have carried out unique eye tests to examine reading styles in young and old people – and discovered for the first time that the way we read words changes as we grow older.
The team from the School of Psychology used an innovative method of digitally manipulating text combined with precise measures of readers’ eye movements. This provides novel insights into how young and older adults use different visual cues during reading.
Their results have been published in the journal Psychology and Aging.
The researchers conducted experiments that used very precise measures of readers’ eye movements to assess how well they read lines of text that had been digitally manipulated to enhance the salience of different visual information. For instance, sometimes the text was blurred and other times the features of the individual letters were sharply defined.
The results showed that whereas young adults (18-30 years) found it easiest to read lines of text when the fine visual detail was present, this was more difficult for older adults (65+years), who found it easier to read more blurred text. These findings support the view that older adults use a different reading strategy from younger adults and that they rely more than young adults on holistic cues to the identities of words, such as word shape.
The research makes an important contribution to understanding why older people have difficulty in reading. The findings will promote further work to more fully understand this difficulty and already points to ways in which it can be combatted.
Filed under elderly word recognition vision eye movements psychology neuroscience science
Smart specs may replace guide dogs
Smart specs for the blind that could take the place of white canes and guide dogs may be available in two years, researchers have said.
The hi-tech glasses are designed to prevent “legally blind” individuals with a small degree of residual vision from bumping into objects.
They use tiny stereo cameras in the frames to project simplified images onto the lenses which become brighter the closer an object is.
From January next year the glasses will be tested in a series of trials involving 160 people with severely impaired sight in Oxford and London. Developer Dr Stephen Hicks, from Oxford University, said he hoped a finished model will be commercially available in around two years.
The cost is expected to be around £600 - slightly more than a smart phone. In comparison, a guide dog costs up to £30,000 to train.
Dr Hicks said the spectacles were designed as a navigational aid, not to restore lost vision.
"The glasses work using a pair of cameras that determine the distance of objects and we simply translate that into a light display," he said. "This is not restoring sight, but we can improve spatial awareness."
Around 300,000 people in the UK are registered as legally blind. Of these, 90% possess some residual vision allowing them to detect blurry shapes and differences between light and dark.
"The aim is to increase the independence of the hundreds of thousands of people who are visually impaired in the UK," said Dr Hicks.
The research was funded through the National Institute for Health Research Invention for Innovation (i4i) programme.
Filed under vision blindness navigation spectacles technology science
Stony Brook Researchers Look Back on Scientific Advances Made as a Result of a 50-Year Old Puzzle
Fifty years after scientists first posed a question about protein folding, the search for answers has led to the creation of a full-fledged field of research that led to major advances in supercomputers, new materials and drug discovery, and shaped our understanding of the basic processes of life, including so-called “protein-folding diseases” such as Alzheimer’s, Parkinson’s and type II diabetes.
In a review article published in the Nov. 23, 2012 issue of the journal Science, Stony Brook University researchers reviewed the progress on a 50-year-old puzzle called the Protein Folding Problem. Ken Dill and Justin MacCallum of Stony Brook’s Louis and Beatrice Laufer Center for Physical and Quantitative Biology show how a community of scientific researchers rose to tackle a grand-challenge problem of very basic science that had no obvious payoff at the time.
“Protein folding is a quintessential basic science. There has been no specific commercial target, yet the collateral payoffs have been broad and deep,” the researchers said in their paper, The Protein Folding Problem, 50 Years On.
“We have learned that proteins fold rapidly because random thermal motions cause conformational changes leading energetically downhill toward the native structure, a principle that is captured in funnel-shaped energy landscapes. And thanks in part to the large Protein Data Bank of known structures, predicting protein structures is now far more successful than was thought possible in the early days. What began as three questions of basic science one half-century ago has now grown into the full-fledged research field of protein physical science.”
Filed under protein folding protein folding diseases neurodegenerative disorders science
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.
Filed under brain brain development pyramidal neurons synapses neuroscience science
Call that a ball? Dogs learn to associate words with objects differently than humans do
Previous studies have shown that humans between the ages of two to three typically learn to associate words with the shapes of objects, rather than their size or texture. For example, toddlers who learn what a ‘ball’ is and are then presented other objects with similar shapes, sizes or textures will identify a similarly-shaped object as ‘ball’, rather than one of the same size or texture.
Earlier research with dogs has shown that they can learn to associate words with categories of objects (such as ‘toy’), but whether their learning process was the same as that of humans was unknown.
In this new study, the scientists presented Gable, a five year old Border Collie, with similar choices to see if this ‘shape bias’ exists in dogs. They found that after a brief training period, Gable learned to associate the name of an object with its size, identifying other objects of similar size by the same name. After a longer period of exposure to both a name and an object, the dog learned to associate a word to other objects of similar textures, but not to objects of similar shape.
According to the authors, these results suggest that dogs (or at least Gable) process and associate words with objects in qualitatively different ways than humans do. They add that this may be due to differences in how evolutionary history has shaped human and dog senses of perceiving shape, texture or size.
Filed under animals word-object associations learning psychology neuroscience science
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.
Filed under brain sleep sleep deprivation studying students memory psychology neuroscience science
