A new theory about sleep's benefits for the brain gets a boost from fruit flies in Science. Researchers at Washington University School of Medicine in St. Louis found evidence that sleep, already recognized as a promoter of long-term memories, also helps clear room in the brain for new learning.

The critical question: How many synapses, or junctures where nerve cells communicate with each other, are modified by sleep? Neurologists believe creation of new synapses is one key way the brain encodes memories and learning, but this cannot continue unabated and may be where sleep comes in.

"There are a number of reasons why the brain can't indefinitely add synapses, including the finite spatial constraints of the skull," says senior author Paul Shaw, Ph.D., assistant professor of neurobiology at Washington University School of Medicine in St. Louis. "We were able to track the creation of new synapses in fruit flies during learning experiences, and to show that sleep pushed that number back down."

Scientists don't yet know how the synapses are eliminated. According to theory, only the less important connections are trimmed back, while connections encoding important memories are maintained.

Many aspects of fly sleep are similar to human sleep; for example, flies and humans deprived of sleep one day will try to make up for the loss by sleeping more the next day. Because the human brain is much more complex, Shaw uses the flies as models for answering questions about sleep and memory.

Sleep is a recognized promoter of learning, but three years ago Shaw turned that association around and revealed that learning increases the need for sleep in the fruit fly. In a 2006 paper in Science, he and his colleagues found that two separate scenarios, each of which gave the fruit fly's brain a workout, increased the need for sleep.

The first scenario was inspired by human research linking an enriched environment to improved memory and other brain functions. Scientists found that flies raised in an enhanced social environment - a test tube full of other flies - slept approximately 2-3 hours longer than flies raised in isolation.

Researchers also gave male fruit flies their first exposure to female fruit flies, but with a catch - the females were either already mated or were actually male flies altered to emit female pheromones. Either fly rebuffed the test fly's attempts to mate. The test flies were then kept in isolation for two days and exposed to receptive female flies. Test flies that remembered their prior failures didn't try to mate again; they also slept more. Researchers concluded that these flies had encoded memories of their prior experience, more directly proving the connection between sleep and new memories.

Scientists repeated these tests for the new study, but this time they used flies genetically altered to make it possible to track the development of new synapses, the junctures at which brain cells communicate.

"The biggest surprise was that out of 200,000 fly brain cells, only 16 were required for the formation of new memories, " says first author Jeffrey Donlea, a graduate student. "These sixteen are lateral ventral neurons, which are part of the circadian circuitry that let the fly brain perform certain behaviors at particular times of day."

When flies slept, the number of new synapses formed during social enrichment decreased. When researchers deprived them of their sleep, the decline did not occur.

Donlea identified three genes essential to the links between learning and increased need for sleep: rutabaga, period and blistered. Flies lacking any of those genes did not have increased need for sleep after social enrichment or the mating test.

Blistered is the fruit fly equivalent to a human gene known as serum response factor (SRF). Scientists have previously linked SRF to plasticity, a term for brain change that includes both learning and memory and the general ability of the brain to rewire itself to adapt to injury or changing needs.

The new study shows that SRF could offer an important advantage for scientists hoping to study plasticity: unlike other genes connected to plasticity, it's not also associated with cell survival.

"That's going to be very helpful to our efforts to study plasticity, because it removes a large confounding factor," says co-author Naren Ramanan, Ph.D., assistant professor of neurobiology. "We can alter SRF activity and not have to worry about whether the resulting changes in brain function come from changes in plasticity or from dying cells."

Shaw plans further investigations of the connections between memory and sleep, including the question of how increased synapses induce the need for sleep.

"Right now a lot of people are worried about their jobs and the economy, and some are no doubt losing sleep over these concerns," Shaw says. "But these data suggest the best thing you can do to make sure you stay sharp and increase your chances of keeping your job is to make getting enough sleep a top priority."

Risky behaviors such as not using condoms or having sex with multiple people put young adults at risk for contracting sexually transmitted diseases, but perhaps not as much as the characteristics of their sexual partners, University of Florida researchers say.

The findings, which UF and University of Pittsburgh researchers report in the April issue of Sexually Transmitted Diseases, could help health-care providers better screen patients for STD risks, said Stephanie A. S. Staras, Ph.D., a UF assistant professor of epidemiology and health policy research in the UF College of Medicine.

"If you are choosing high-risk partners, you are much more likely to have an STD, even when we account for your condom-use patterns," said Staras, the lead author of the study. "The theory is simple: You need to have sex with someone who has an STD to get an STD. Based on the prevalence of STDs in the United States, it seems like the public may not fully understand their risk."

The study examined the sexual activities, partner characteristics and STD diagnoses of 412 subjects between the ages of 15 and 24. Among the subjects whose partners were categorized as high-risk, half were diagnosed with an STD. By comparison, about 40 percent of the young adults whose own behaviors were labeled as high-risk were diagnosed with an STD.

According to the Centers for Disease Control and Prevention, about 19 million people in the United States contract STDs each year. About half of them are between the ages of 15 and 24.

Health-care providers often ask patients about their own sexual behaviors, but inquiring only about a person's own behaviors may cause some patients to slip through the cracks, Staras said. For example, some subjects in the study reported very low-risk behaviors but were having sex with very high-risk partners.

Adding a few simple questions about partner characteristics during STD screenings could help providers catch more patients who need to be tested and educated about condom use and other protective measures, Staras said.

"Partner selection is an area of STD prevention that could complement what we are already doing with promoting condom use, and could possibly really help people," Staras said. "If somehow we could convince individuals to incorporate this information in a meaningful way into their decision-making, then we could reduce STDs."

UF researchers measured five specific characteristics to gauge how risky certain partners were. These characteristics included whether the partner has a problem with marijuana or alcohol, was at least five years older or younger, had been in jail, had sex with other people in the past year or had an STD in the past year.

The researchers then created a composite, totaling up the number of negative partner characteristics for each subject and comparing them against the number of each person's own individual risky behaviors, which ranged from how often they used condoms to how many people they had sex with.

Overall, researchers found considering all of the partner characteristics together was the strongest predictor for STDs. Young adults whose partners had five or more risk characteristics were three times more likely to have an STD than those whose partners had no more than two characteristics.

Of these characteristics, the most telling were if a partner already had an STD and if a couple had an age difference of more than five years. Subjects whose partners were five years older or younger than them were more than twice as likely to be diagnosed with an STD than those whose partners were around the same age, the researchers found.

"It's all about the risk of the partner and sometimes we forget that," said Richard A. Crosby, Ph.D., the DDI endowed professor and chairman of the department of health behavior at the University of Kentucky and a co-director of the Rural Center for AIDS/STD Prevention.

But Crosby, who was not involved in the UF study, said it's also important for people to remember that the risks mentioned in the study are just generalizations, not set-in-stone giveaways for STDs.

"From a public health perspective, it's important to understand these findings," he said. "From a practical and prevention perspective, we still need to rely on people using valid methods of protection to avoid being infected or infecting."

As we look at the world around us, images flicker into our brains like so many disparate pixels on a computer screen that change every time our eyes move, which is several times a second. Yet we don't perceive the world as a constantly flashing computer display.

Why not?

Neuroscientists at The Johns Hopkins University think that part of the answer lies in a special region of the brain's visual cortex which is in charge of distinguishing between background and foreground images. Writing in a recent issue of the journal Neuron, the team demonstrates that nerve cells in this region (called V2) are able to "grab onto" figure-ground information from visual images for several seconds, even after the images themselves are removed from our sight.

"Recent studies have hotly debated whether the visual system uses a buffer to store image information and if so, the duration of that storage," said Rudiger von der Heydt, a professor in Johns Hopkins' Zanvyl Krieger Mind-Brain Institute, and co-author on the paper. "We found that the answer is 'yes,' the brain in fact stores the last image seen for up to two seconds."

The image that the brain grabs and holds onto momentarily is not detailed; it's more like a rough sketch of the layout of objects in the scene, von der Heydt explains. This may elucidate, at least in part, how the brain creates for us a stable visual world when the information coming in through our eyes changes at a rapid-fire pace: up to four times in a single second.

The study was based on recordings of activity in nerve cells in the V2 region of the brains of macaques, whose visual systems closely resemble that of humans. Located at the very back of the brain, V2 is roughly the size of a wristwatch strap.

The macaques were rewarded for watching a screen onto which various images were presented as the researchers recorded the animals' brain nerve cells' response. Previous experiments have shown that the nerve cells in V2 code for elementary features such as pieces of contour and patches of color. What is characteristic of V2, though, is that it codes these features with reference to objects. A vertical line, for instance, is coded either as the contour of an object on the left or as a contour of an object on the right. In this study, the researchers presented sequences of images consisting of a briefly-flashed square followed by a vertical line. They then compared the nerve cells' responses to the line when it was preceded by a square on the left and when it was preceded by a square on the right. The recordings revealed that the V2 cells remember the side on which the square had been presented, meaning that the flashing square set up a representation in the brain that persisted even after the image of the square was extinguished.

Von der Heydt said that discovering memory in this region was quite a surprise because the usual understanding is that neurons in the visual cortex simply respond to visual stimulation, but do not have a memory of their own.

Though this research is only a small piece of the "how people see and process images" puzzle, it's important, according to von der Heydt.

"We are trying to understand how the brain represents the changing visual scene and knows what is where at any given moment," von der Heydt said. "How does it delineate the contours of objects and how does it remember which contours belong to each object in a stream of multiple images? These are important and interesting questions whose answer may someday have very practical implications. For instance, how we function under conditions that strain our ability to process all relevant information - whether it be driving in city traffic, surveying a large crowd to find someone, or something else, may depend in large part on what kind of short-term memory our visual system has."

Understanding how this brain function works is more than just interesting. Because this study shows how the strength and duration of the memory trace can be directly measured, it may eventually be possible to understand its mechanism and to identify factors that can enhance or reduce this important function. This could assist researchers in unraveling the causes of - and perhaps even identifying treatment for - disorders such as attention deficit disorder and dyslexia.

A study conducted in India suggested taking a single capsule containing five drugs: a statin, aspirin and three blood pressure drugs, could significantly cut the risk of heart disease among healthy people without side effects.

The phase II clinical trial was the work of principal investigator Dr Salim Yusuf of McMaster University, Hamilton, Ontario, Canada, and colleagues, and the findings appear in the 30 March online issue of The Lancet. They were also presented at the Annual Scientific Session of the American College of Cardiology.

Yusuf, an epidemiologist and cardiologist, is a professor of medicine for the Michael G. DeGroote School of Medicine, vice-president of research and chief scientific officer at Hamilton Health Sciences and director of the Population Health Research Institute. He and colleagues did the trial in India because polypills are already available there.

The drug they tested is called Polycap, and is made by Cadila Pharmaceuticals of India. Polycap contains a beta-blocker, a diuretic, an ACE inhibitor, a statin, and aspirin. These ingredients are usually prescribed as individual drugs for treating people with cardiovascular disease or at risk of cardiovascular disease.

In the trial, known as The Indian Polycap Study (TIPS), Yusuf and colleagues tested the polypill against its component drugs and selected combinations of the components.

TIPS is the first double-blind, randomized trial to evaluate the tolerability of the Polycap as well as its impact on cardiovascular risk factors.

The findings suggested that the polypill could reduce heart disease by 62 per cent and stroke by 48 per cent but more studies are needed to decide the optimum combination of drugs that should go into the pill.

There has been a lot of debate about using polypills to protect against cardiovascular diseases.

The idea was first raised by Yusuf in an editorial in The Lancet in 2002. Two scientists, Nicholas Wald and Malcolm Law, took the idea further in an article that appeared 12 months later in the British Medical Journal. They suggested if everyone over the age of 55 and everyone with cardiovascular disease took such a pill, it would reduce the incidence of cardiovascular disease by over 80 per cent, and largely prevent heart attacks and stroke.

Doctors, nurses and others who provide health care to older adults are often so focused on acute medical problems that they may miss symptoms of cognitive impairment. A unique educational summit to be held in April and May in Indianapolis focuses on the problem and will enhance the skills of these health-care providers in recognizing and managing cognitive impairment. The goal is to enable older adults to remain in their homes.

According to Malaz Boustani, M.D., associate professor of medicine at the Indiana University School of Medicine and a Regenstrief Institute research scientist, more than half of Americans with cognitive impairment are not recognized as having the conditions when they go to a hospital and more than three-quarters are not recognized as having cognitive impairment by their primary care physicians. The result is that less than 10 percent receive medications appropriate to their level of cognitive impairment and approximately one-quarter receive medications which are inappropriate.

"Medical professionals who care for older adults are faced with the problems of the real world - providing the best care to patients with multiple acute and chronic diseases under time constraints and reimbursement pressures. We hope with this summit to provide these committed individuals with tools that will help them to identify the red flags of cognitive impairment - to recognize delirium as an urgent medical syndrome, to reduce exposure to inappropriate medications, and to enable them to employ non-pharmacological methods to manage the special needs of both the patient and his family caregiver," said Dr. Boustani.

Dr. Boustani, who is a center scientist with the IU Center for Aging Research, is also the research director for the Indianapolis Discovery Network for Dementia. IDND, fostered by the research of the Regenstrief Institute, is an expanding group of researchers, clinicians, caregivers and community advocates who are working to enhance dementia care in the nation's twelfth largest city. IDND is a national model for how members of the community, caregivers, clinicians and researchers can work together to improve the delivery of dementia care.

Nearly 360 health-care providers from throughout Indiana will participate in the multi-session summit, which is funded by a $75,000 grant from Pfizer Pharmaceuticals to the Medical Education Group of Community Home Health Services. CHHS, which provides home health-care services, has partnered with IDND to sponsor the summit. In late 2007, IDND launched RAPID-PC - Recognizing and Assessing the Progression of Cognitive Impairment and Dementia in Primary Care, a highly successful program.

"We hope that this summit will serve as both a local resource and a national model which will spawn similar educational opportunities to help doctors, nurses and others who take care of older adults in their homes to better deal with their often unrecognized mental health needs," said Jessie Westlund, R.N. of Community Home Health Services, part of Community Health Network.