In mammals, the production of new brain cells occurs primarily at the time the nervous system is developing, although certain brain areas generate neurons throughout adulthood. One such area is the hippocampus, a part of the brain involved in the critical function of memory and spatial perception. Hippocampal cells, specifically dentate granule cells, are continuously produced in adults as well as in young animals. How these "adult-born" cells build their connections with the rest of the brain, and the extent to which they resemble "pup-born" cells, is of great interest to those who would like to coax other parts of adult brains to make new cells as a strategy for reversing the loss of function from trauma or degenerative disorders. To find out whether adult-born hippocampal neurons have different properties than mature neurons that arose when the brain was developing, Diego Laplagne, Alejandro Schinder, and colleagues compared how each type of neuron incorporated functionally into brain circuits. The researchers' first task was to figure out a way to distinguish between pup-born and adult-born neurons in brain tissue that contained both. To accomplish that task, they used retroviruses to introduce one kind of fluorescent protein into the developing neurons and a second protein into the adult mouse brain. As a result of this treatment, the pup-born cells fluoresced green and the adult-born cells fluoresced red, making them readily distinguishable in brain slices. Once they could tell the two types of cells apart, the researchers gained insight into the connections formed. They looked at glutamatergic (excitatory) nerves connecting the hippocampus with the entorhinal cortex, another brain area associated with memory. When they stimulated the excitatory inputs carrying information from the neocortex to the hippocampus, the researchers evoked similar responses in both pup-born and adult-born neurons.

Keyword: Neurogenesis
Link ID: 9648 - Posted: 11.21.2006

WASHINGTON -- Males experience more traumatic events on average than do females, yet females are more likely to meet diagnostic criteria for Posttraumatic Stress Disorder (PTSD), according to a review of 25 years of research reported in the November issue of Psychological Bulletin, published by the American Psychological Association (APA). The authors reviewed 290 studies conducted between 1980 and 2005 to determine who is more at risk for potentially traumatic events (PTE) and posttraumatic stress disorder (PTSD) – males or females? The results of the meta-analysis found that while males have a higher risk for traumatic events, women suffer from higher PTSD rates. PTSD is defined as an anxiety disorder precipitated by a traumatic event and characterized by symptoms of re-experiencing the trauma, avoidance and numbing and hyperarousal. From the review, researchers David F. Tolin, PhD of the Institute of Living and Edna B. Foa, PhD, of the University of Pennsylvania School of Medicine found that female study participants were more likely than male study participants to have experienced sexual assault and child sexual abuse, but less likely to have experienced accidents, nonsexual assaults, witness death or injury, disaster or fire and combat or war. Sexual trauma, the authors conclude, may cause more emotional suffering and are more likely to contribute to a PTSD diagnosis than other types of trauma.

Keyword: Stress; Sexual Behavior
Link ID: 9647 - Posted: 06.24.2010

Researchers studying chimpanzee mating preferences have found that although male chimpanzees prefer some females over others, they prefer older, not younger, females as mates. The findings uncover a stark contrast between chimpanzee behavior and that of humans, their primate cousins. The basis for this difference may lie in the fact that whereas chimpanzees participate in a relatively promiscuous mating system, humans form unusually long-term mating bonds, thereby making young females more valuable as mates with greater reproductive potential. The findings, reported by Martin Muller of Boston University and colleagues at Harvard University, appear in the November 21st issue of Current Biology. Theoretical explanations for the preference of human males for young females as mates include the facts that humans tend to form long-term mating partnerships, and that female fertility is limited by menopause and, therefore, age. The converse of such an explanation suggests that species that appear to lack long-term pair bonding and menopause (such as chimpanzees) should not exhibit such strong preferences by males for young females. In the new work, researchers examined this idea by studying male mate preferences within the Kanyawara chimpanzee community in Kibale National Park in Uganda. The researchers found that, in contrast to humans, male chimpanzees prefer older females to younger ones. They found that, compared to younger females, older females were more likely to be approached for copulation, were more often in association with males during estrous periods, copulated more frequently with high-ranking males, and gave rise to higher rates of male-on-male aggression in mating contests.

Keyword: Sexual Behavior
Link ID: 9646 - Posted: 11.21.2006

Roxanne Khamsi In Star Wars, Obi-Wan Kenobi was on the right track in his advice to the young Luke Skywalker. People are fooled by magic tricks, even if their eyes see past the illusion, a new study reveals. The tricks work by distorting our perception, even though they do not fool our eyes, the research shows. The study demonstrates that the brain pathways for eye movement and perception operate independently, the researchers say. Gustav Kuhn at the University of Durham, UK, who is a neuroscientist and also a magician, showed 38 students a video clip of the “vanishing ball” illusion. Watch a brief clip of the trick (mov format). In the trick, the magician throws a ball into the air twice and catches it. On the third, fake throw, the ball seems to disappear into the air even though it never leaves his hand. Most of the students watching the trick were fooled by the magician looking up on the third throw – 68% perceived the ball as leaving his hand. To understand how volunteers were fooled, Kuhn and colleagues filmed their eyes as they watched the trick and used special software to calculate where they had looked. Most people glanced quickly at the magician’s face before tracking the ball, the researchers found. © Copyright Reed Business Information Ltd.

Keyword: Vision
Link ID: 9645 - Posted: 06.24.2010

(WebMD) A new study on marijuana and memory may show why using pot hampers memory. The study appears in Nature Neuroscience's advance online edition. Researchers included David Robbe, Ph.D., of the Center for Molecular and Behavioral Neuroscience at Rutgers, the State University of New Jersey. The study was in rats, not people. The researchers gave rats shots of a synthetic cannabinoid drug that resembles marijuana's active ingredient, THC (tetrahydrocannabinol). The drug doses were "comparable with recreational and palliative [pain relief] uses in humans," note Robbe and his colleagues. For comparison, other rats got saltwater shots without cannabinoids. Twenty minutes later, the scientists started monitoring the activity of certain nerve cells, or neurons, in the rats' brains. Those neurons normally send chemical signals to communicate with each other. The process occurs seamlessly, like musicians playing in sync with each other in an orchestra. ©MMVI, CBS Broadcasting Inc.

Keyword: Drug Abuse; Learning & Memory
Link ID: 9644 - Posted: 06.24.2010

The tiniest wires that link neurons to one another probably serve a critical role in the brain's computational function. New data about how these wires, or dendritic spines, modulate their electrical properties and receive incoming signals is giving scientists a more complete view of their knack for acting as efficient mathematical calculators. Moreover, the findings also hint that these dendritic spines could make the human brain a far more efficient learning machine than that of other animals. Howard Hughes Medical Institute investigator Rafael Yuste and his colleagues at Columbia University published their findings about dendritic spines in a trio of papers in the Proceedings of the National Academy of Sciences (PNAS). During development, as the brain is laying down its intricate neural circuits, individual neurons must also be able to adjust their sensitivity to incoming signals so that they can process information. The new research sheds significant light on a century-old mystery of how dendritic spines contribute to this process, the scientists said. Neurons are the wiring along which nerve signals are propagated throughout the brain and spinal cord. Chemical signals called neurotransmitters signal neighboring cells to initiate their own electrical impulses. These neurotransmitters are received along branching extensions of a nerve cell called dendrites. From each of the many dendrites on a nerve cell's surface sprouts a forest of mushroom-shaped spines. The head of each mushroom is covered with receptors that bind neurotransmitters that are launched in bursts across the synapse, the junction between nerve cells. Each spine has a filamentous neck that supports the head. These structures are ubiquitous: spines cover most neurons in the brain and are responsible for mediating close to 90 percent of all brain connections. © 2006 Howard Hughes Medical Institute.

Keyword: Development of the Brain; Learning & Memory
Link ID: 9643 - Posted: 06.24.2010

Wasps have more than just a sting in their tail according to new research published this week in the Proceedings of the Royal Society B, they also carry the insect version of pepper spray in their heads, which they can release when fighting other wasps. The research not only gives us a fascinating insight into insect behaviour but could also help us to use wasps to kill crop destroying pests. For the first time scientists, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), have recorded 'chemical exchanges' undetectable by the human nose which take place between females of a species of bethylid wasp - Goniozus legneri, when they fight over larvae on which they lay their eggs. Not only have they discovered that chemical exchanges take place, but also that it is always the losing wasp that releases the potent gas. While the research was primarily aimed at improving the understanding of animal behaviour, lead researcher Dr Ian Hardy, from the University of Nottingham, explains that there is great potential for applied spin-offs: "Bethylid wasps kill the larvae of many insects that are pests of crops, such as almonds, coffee and coconut, ruining harvests and costing industry thousands of pounds. These wasps could be used as a cheap and effective biological control to kill the larvae, avoiding the use of expensive and polluting pesticides. But for successful biological control, we need a good knowledge of wasp behaviour, including how wasps from the same and different species interact. Understanding these patterns can inform us of the best combinations of species to release against a given crop pest."

Keyword: Aggression
Link ID: 9642 - Posted: 11.21.2006

Boston, MA -- Fighting like a girl or fighting like a boy is hardwired into fruit fly neurons, according to a study in the Nov. 19 Nature Neuroscience advance online publication by a research team from Harvard Medical School and the Institute of Molecular Pathology in Vienna. The results confirm that a gene known as "fruitless" is a key factor underlying sexual differences in behavior. The findings mark a milestone in an unlikely new animal model for understanding the biology of aggression and how the nervous system gives rise to different behaviors. "Aggression is a very serious problem in society, and it's a problem with a biological and genetic component," said co-author Edward Kravitz, the George Packer Berry professor of neurobiology at HMS, who developed the fruit fly fighting model used. "We want to understand that. I can't think of a better system to study than fruit flies. And no one gets hurt." The fruitless gene is known for its role in male courtship. The large gene makes a set of male-specific proteins found exclusively in the nervous system of fruit flies, in about 2 percent of neurons. The proteins are necessary for normal courting. Males missing the proteins do not court females, and they sometimes court males, other research groups have shown. Females with a male version of the gene perform the male courting ritual with other females. The same gene directs another sex-specific behavior – fighting patterns, the new study shows. Female fighting, for example, largely involves head butts and some shoving. Males prefer lunges; they rear up on their back legs and snap their forelegs down hard – sometimes nailing an opponent that is slow to retreat.

Keyword: Aggression; Sexual Behavior
Link ID: 9641 - Posted: 06.24.2010

A new test may help researchers understand why a toxin builds up in the brains of Alzheimer's patients. Amyloid beta protein accumulates in the brain in Alzheimer's disease but whether the body produces too much or cannot break it down is unclear. But by labelling the protein with a carbon isotope, doctors can measure the rate of turnover, a report in Nature Medicine suggests. Experts said the test could help improve diagnosis and treatment. Doctors are already able to measure amounts of amyloid beta protein - or abeta - in the cerebrospinal fluid but that doesn't indicate why the build-up is occurring. By working out whether the body is producing too much or is unable to break it down, researchers develop drugs too accurately target the right process. Furthermore, the test may also prove useful in the diagnosis of Alzheimer's prior to the onset of clinical symptoms. The team at the Washington School of Medicine gave eight healthy volunteers an intravenous infusion which contained an amino acid - Leucine - that had carbon molecules with one extra neutron. They then took samples of cerebral spinal fluid - the fluid that surrounds the brain - over a period of 36 hours. The body uses amino acids to form proteins so the researchers were able to measure how the carbon isotope was taken up in the production of amyloid beta protein and then how long it took to break the labelled proteins down. They found the the production rate of the amyloid protein was 7.6% per hour and the clearance rate was 8.2% per hour - much faster than anyone had predicted. "Abeta has the second-fastest production rate of any protein whose production rate has been measured so far," said lead author Dr Randall Bateman, assistant professor of neurology at Washington University Medical School. "In a time span of about six or seven hours, you make half the amyloid beta found in your central nervous system." (C)BBC

Keyword: Alzheimers
Link ID: 9640 - Posted: 11.18.2006

By Steven Reinberg FRIDAY, (HealthDay News) -- Adding further weight to the theory that fish may be brain food, new research found that people with diets rich in fish have a significantly lower risk of dementia and Alzheimer's disease. The key appears to be docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid that appears to affect dementia risk and to be important for the proper functioning of the central nervous system. "If you have a high level of DHA, a fatty acid found in fish, it reduced your risk of dementia by about half," said study lead researcher Dr. Ernst J. Schaefer, senior scientist and director of the Lipid Metabolism Laboratory at the Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University in Boston. It's known that omega-3 fatty acids protect the heart and the circulatory system. "Just as fish is good for your heart, it's probably good for your brain as well," Schaefer said. Fatty fish like mackerel, lake trout, herring, sardines, albacore tuna and salmon are high in DHA. The study findings are published in the November issue of theArchives of Neurology. © 2006 Scout News LLC.

Keyword: Alzheimers
Link ID: 9639 - Posted: 06.24.2010

Call them laser-guided smart bombs for brain tumors. Researchers at the University of Michigan announced the testing of a drug delivery system that involves drug-toting nanoparticles and a guiding peptide to target cancerous cells in the brain. Their study finds that via this method more of the drug can be delivered to a tumor's general vicinity. They report their findings in the November 15 issue of Clinical Cancer Research. The researchers used a pharmaceutical called Photofrin, which is photodynamic, meaning it is activated by a laser after it has entered the bloodstream. As its primary side effect, the drug renders patients photosensitive, and they must remain out of bright sunlight and even unshaded lamps for up to 30 days after receiving treatment. Despite this major drawback, Photofrin is used in the treatment of esophageal, bladder and skin cancers. But their novel delivery system, which relies on the intravenous delivery of 40-nanometer-wide particles to carry the drug, may actually avoid much of the photosensitivity, because less Photofrin circulates in the bloodstream thanks to a peptide called F3. A sequence of 31 amino acids broken off of the protein HMGN2 (high mobility group protein 2), F3 has the ability to penetrate cell membranes. "This peptide acts as a "zip code" in that it enables the binding of the nanoparticles only to blood vessels within the tumor and not normal blood vessels," says Alnawaz Rehemtulla, a radiologist and environmental health scientist who co-authored the study. F3 can detect the expression of a protein called nucleolin, which is a marker on the surface of tumor cells. Another problem the researchers avoided was having to deliver their medicine in such a way that it could cross the blood-brain barrier, which keeps many substances from entering the brain from the bloodstream. © 1996-2006 Scientific American, Inc.

Keyword: Miscellaneous
Link ID: 9638 - Posted: 06.24.2010

By Andrew Lawler The Nobel Prize-winning director of a neuroscience center at the Massachusetts Institute of Technology (MIT) is stepping down in the wake of a controversy over the abortive hiring of a young female biologist in June. In a 16 November letter to MIT Provost Rafael Reif and Science Dean Robert Sibley, Susumu Tonegawa, who leads the Picower Institute for Learning and Memory, said he would resign as director on 31 December, "when my appointment expires, so I can devote all my energy and focus to research." Tonegawa's resignation comes 5 months after MIT's unsuccessful courtship of Alla Karpova, a postdoctoral fellow now at Cold Spring Harbor Laboratory in New York. Karpova ended up turning down a faculty position at MIT's McGovern Institute for Brain Research. On 2 November a panel examining the incident, in which Tonegawa sent "inappropriate" e-mails to Karpova to discourage her from taking the job, issued a report that criticized the conduct of Tonegawa and other faculty members. The report also said the behavior illuminated a lack of clear mission for the school's many-faceted neuroscience effort and turf battles between its various institutes (ScienceNOW, 3 November). © 2006 American Association for the Advancement of Science

Keyword: Sexual Behavior
Link ID: 9637 - Posted: 06.24.2010

Bruce Bower Welcome to the era of Neandertal genetics. Researchers announced this week that they have retrieved and analyzed a huge chunk of Neandertal DNA, covering more than 1 million of the roughly 3 million paired chemical constituents of an individual's genetic makeup. Until now, scientists had extracted small DNA segments from Neandertal bones, mainly from mitochondria outside cell nuclei (SN: 4/1/00, p. 213: http://www.sciencenews.org/articles/20000401/fob2.asp). Two new techniques have now recovered large amounts of genetic material from nuclei. One also permits tagging of ancient DNA sequences that correspond to modern human genes. A team led by Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, presents results from the first new technique in the Nov. 16 Nature. A group directed by Edward M. Rubin of the U.S. Department of Energy Joint Genome Institute in Walnut Creek, Calif., describes results from the second technique in the Nov. 17 Science. These new studies "foreshadow an exciting development—the recovery of the complete Neandertal genome," comment David M. Lambert of Massey University in Auckland, New Zealand, and Craig D. Millar of the University of Auckland, in an editorial published with the Nature report. Pääbo and his colleagues expect to complete the genome within 2 years. ©2006 Science Service.

Keyword: Evolution
Link ID: 9636 - Posted: 06.24.2010

Jennifer Viegas, Discovery News — It may not be language as we know it, but whales have no shortage of ways to make themselves understood. So broad is their vocal repertoire, in fact, that whales can call to their young, woo potential mates and even express emotions, according to researchers who have identified 622 social sounds in humpback whales. Their work will be presented at the upcoming joint meetings of the Acoustical Society of America (ASA) and the Acoustical Society of Japan in Hawaii. Social sounds are brief, unpatterned sounds that are distinct from lengthier, complex whale songs. The new research adds to a growing body of evidence that whales convey more meaning through vocalizations than previously thought. "I wouldn't say (whales possess) language, as that's a human term," Rebecca Dunlop told Discovery News. Dunlop, who worked on the study, is a researcher in the School of Veterinary Sciences at the University of Queensland, Australia. "Whales don't string these sounds together like words and form sentences. It's more like a simple vocabulary," she said. The scientists visually tracked 60 pods of whales migrating along the east coast of Australia. The researchers used a static hydrophone array — sensitive equipment that detects sound waves — linking the whale sounds to various activities and contexts. © 2006 Discovery Communications Inc.

Keyword: Animal Communication; Language
Link ID: 9635 - Posted: 06.24.2010

Scientists have worked out which parent to blame if you are unhappy with your weight or height. Fathers appear to determine the height of their child while mothers tend to influence how much body fat they will have, a study suggests. The work is ongoing, but researchers from the Royal Devon and Exeter Hospital say the initial results are clear - taller dads make longer babies. How fat the father is does not seem to influence a child's fatness, however. In contrast, whether the mother is fat or not has a major effect on the birth weight of the baby, the team found. This is likely to be down to the environment in the womb - with overweight mums tending to have higher levels of sugar in their blood. Research midwife Dr Beatrice Knight stressed both genetic and environmental factors influence in a child's growth. The early growth of the baby, both in the womb and in the first few years of life, may be crucial for the development of their health in later life, she said. By identifying the genes involved in this early growth, she hopes to develop a better understanding of how these things are linked. They have been studying about 1,000 families, measuring the weight and height of the mums, dads and their babies in their first two years of life. Dr Knight said: "Obviously one of the biggest influences on a baby's growth is the size of the mother. But we have confirmed that a father's height also has a direct impact on their baby's growth, with taller dads having longer and heavier babies." (C)BBC

Keyword: Genes & Behavior; Obesity
Link ID: 9634 - Posted: 11.17.2006

By Rob Stein A component of red wine recently shown to help lab mice live longer also protects animals from obesity and diabetes and boosts their physical endurance, researchers reported yesterday. The new research helps confirm and extend the possible benefits of the substance, resveratrol, and offers new insight into how it works -- apparently by revving up the metabolism to make muscles burn more energy and work more efficiently. Mice fed large doses could run twice as far as they would normally. In addition, the scientists for the first time produced evidence linking the biological pathway activated by the substance to human physiology, showing that the same genetic switch resveratrol mimics seems to naturally endow some people with faster metabolisms. "It's very exciting," said Johan Auwerx, a professor of medicine at the Institute of Genetics and Molecular and Cellular Biology in Strasbourg, France, who led the research being published online and in the Dec. 15 issue of the journal Cell. "This compound could have many applications -- treating obesity and diabetes, improving human endurance, helping the frail. There's a lot of potential." Auwerx and other researchers cautioned much more research is needed to study the compound and similar agents, especially to see if the approach is safe for people. Humans would have to take hundreds of resveratrol pills sold in health food stores or drink hundreds of glasses of wine a day to get equivalent levels of the substance tested on the mice, neither of which would be safe. But the new research adds to the growing enthusiasm about the approach, experts said. © 2006 The Washington Post Company

Keyword: Obesity
Link ID: 9633 - Posted: 06.24.2010

David F. Salisbury Much like the electrical wiring in your house, the nerves in your body need to be completely covered by a layer of insulation to work properly. Instead of red, white or black plastic, however, the wiring in the nervous system is protected by layers of an insulating protein called myelin. These layers increase the speed that nerve impulses travel throughout the brain and the body. The critical role they play is dramatically illustrated by the symptoms of multiple sclerosis, which is caused by lesions that destroy myelin. These include: blindness, muscle weakness and paralysis, loss of coordination, stuttering, pain and burning sensations, impotence, memory loss, depression and dementia. The formation of myelin sheaths during development requires a complex choreography generally considered to be one of nature’s most spectacular examples of the interaction between different kinds of cells. Now, a group of Vanderbilt researchers has successfully produced movies that provide the first direct view of the initial stage of this process: the period when the cells that ultimately produce the myelin sheathing spread throughout the developing nervous system. The results were published online in the journal Nature Neuroscience on Nov. 12 and should aid in the design of new therapies to promote the repair of this protective layer following disease or injury.

Keyword: Development of the Brain
Link ID: 9632 - Posted: 06.24.2010

Researchers at the University of Minnesota's Institute for Human Genetics have shown for the first time that the severity of an adult neurodegenerative disease is tied to how well the brain developed shortly after birth. The researchers used a mouse model for spinocerebellar ataxia type 1 (SCA 1), a fatal neurodegenerative disease that is associated with the loss of coordination that affects activities such as walking, speaking and swallowing. There is no treatment for this disease, and patients typically die 10-15 years after their first symptoms appear. "We always suspected that something was going on with the SCA 1 mice developmentally," said Harry Orr, Ph.D., professor of genetics, cell biology and development. "Now, we have the data to support it." The research will appear in the Nov. 17, 2006 issue of the journal Cell. Orr and his team manipulated the mouse model for the disease so that the gene that causes SCA 1 could be turned on and off. In one group of mice, they turned off the gene for approximately two weeks at the beginning of the mice's development; then it was turned back on. In the second group of mice, they left the gene on for the entire time. After 12 weeks, the researchers observed the mice. "The difference was dramatic," Orr said.

Keyword: Development of the Brain; Movement Disorders
Link ID: 9631 - Posted: 11.17.2006

Richard A. Friedman, M.D. On Sunday afternoon, September 3, 2006, Wayne Fenton, a prominent schizophrenia expert and an associate director at the National Institute of Mental Health (NIMH), was found dead in his office. He had just seen a 19-year-old patient with schizophrenia who later admitted to the police that he had beaten Fenton with his fists. This tragic incident was widely publicized and raises, once again, the controversial question about the potential danger posed by people with mental illness. The killing also left many in the mental health and medical communities concerned about their own safety in dealing with psychotic patients. After all, if an expert like Fenton, who understood the risks better than most, could not protect himself, who could? It is not an idle question. According to the National Crime Victimization Survey for 1993 to 1999, conducted by the Department of Justice, the annual rate of nonfatal, job-related, violent crime was 12.6 per 1000 workers in all occupations. Among physicians, the rate was 16.2 per 1000, and among nurses, 21.9 per 1000. But for psychiatrists and mental health professionals, the rate was 68.2 per 1000, and for mental health custodial workers, 69.0 per 1000. For Tim Exworthy, a forensic psychiatrist at Redford Lodge Hospital in London who was recently assaulted by a patient, the risk of job-related violence is no longer a dry statistic. © 2006 Massachusetts Medical Society.

Keyword: Schizophrenia; Aggression
Link ID: 9630 - Posted: 06.24.2010

ANN ARBOR, Mich. -- Many women experience declines in their memory during and after menopause, a change thought to be due, in part, to the rapid hormonal changes they weather during that time. Now, research from the University of Michigan Health System suggests that hormone therapy might help women retain certain memory functions. In a study in the new issue of The Journal of Clinical Endocrinology & Metabolism, they report that a group of postmenopausal women showed more brain activity during a visual memory test than did women who were not taking the hormone therapy. The 10 postmenopausal women in the study, ages 50-60, were given hormone therapy or a placebo for four weeks, followed by a month with no medications, and then four weeks of the other treatment. Their brain activation was measured as they were shown a complex grid of 81 squares, with 40 of them darkened to form a pattern. Participants were asked to find the matching image from a choice of two, with the new set of images presented after varying time periods (one to four seconds). During the time that the two images were shown, participants were asked to choose the one that matched the initial grid by pressing one of two buttons on an MRI (magnetic resonance imaging)-compatible response pad. Those who were taking combined estrogen-progestin hormone therapy showed significantly increased activity in the prefrontal cortex, a region of the brain that is critical in memory tasks, compared with those on placebo (a pill with no medicinal value).

Keyword: Hormones & Behavior; Learning & Memory
Link ID: 9629 - Posted: 11.17.2006