Posts tagged neuroscience
Articles and news from the latest research reports.
360 degree brain
This interactive feature gives visitors a chance to get a close-up of the brain’s structure. This brain was removed from a man’s skull shortly after his death and came from the Parkinson’s UK Brain Bank at Imperial College.
How Driving a Taxi Changes London Cabbies’ Brains
Every black-cab driver in central London has to have “The Knowledge” — a memorized map of the capital, including some 25,000 streets and thousands of landmarks, right down to the order of theaters on Shaftesbury Avenue.
It’s a brutal learning process that can take three to four years to complete, with a final test — the Knowledge of London Examination System — that often takes 12 attempts to pass. Even then, ultimately only half of the trainee cabbies ace the exam.
According to a report published in the journal Current Biology, successfully learning this mental atlas of London’s spaghetti streets causes structural changes in the brain, affects memory and creates a greater volume of nerve cells in the brain’s hippocampus.
Music to Your Brain by Dwayne Godwin and Jorge Cham
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.
Teenager Suffering From “Sleeping Beauty” Syndrome
Kleine-Levin syndrome is a rare sleep disorder characterised by recurrent episodes of excessive sleep and altered behaviour. People affected by this syndrome may sleep for up to 20 hours per day (hypersomnia), waking only to eat or go to the bathroom. The start of each episode is characterised by progressive drowsiness and episodes may last for days, weeks, or even months.
During episodes, other symptoms experienced include:
- Compulsive overeating
- Irritability
- Disorientation
- Lack of energy
- Lack of emotion
- Hypersensitivity to noise and light
- Impulsive behaviour
- Hallucinations
- Abnormally uninhibited sex drive.
Episodes are debilitating and during an episode normal daily activities, such as work or school, stop. On recovery, total or partial loss of memory (amnesia) of what has happened is usual. There may be a short period of depression, or sometimes euphoria and sleeplessness. Episodes may not occur for weeks, months or even years, but then reappear without warning.
Between episodes, physical and mental health is usually normal. There appears to be no relationship between Kleine-Levin syndrome and other neurological disorders, such as epilepsy. This syndrome occurs mostly in young males between the ages of 15 and 25 years. It is uncommon after the age of 40 years. The cause of Kleine-Levin syndrome is unknown.
Diagnosis and Treatment
As disturbance of sleep and altered behaviour may accompany a number of physical and psychiatric conditions, diagnosis of Kleine-Levin syndrome is often difficult and delayed. In order to make an accurate diagnosis a careful medical history needs to be taken and tests to rule out other conditions should be performed. These tests may include blood tests and sleep studies.
The person may be referred to various specialists, including a psychiatrist and neurologist. The neurologist will undertake an evaluation of the nervous system to exclude structural abnormalities of the brain. The psychiatrist will look at any underlying behavioural problems.
Currently there is no formal treatment for Kleine-Levin syndrome due to the lack of knowledge regarding its underlying cause. Stimulant medications, such as amphetamines, may be prescribed to treat sleepiness. Medications to treat mood disturbances and depression may also be recommended.
(Source: Southern Cross)
… 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)
Researchers find fly receptor neurons able to communicate without synapse connections
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)
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.