By Michael S. Wolfe The human brain is a remarkably complex organic computer, taking in a wide variety of sensory experiences, processing and storing this information, and recalling and integrating selected bits at the right moments. The destruction caused by Alzheimer's disease has been likened to the erasure of a hard drive, beginning with the most recent files and working backward. An initial sign of the disease is often the failure to recall events of the past few days--a phone conversation with a friend, a repairman's visit to the house--while recollections from long ago remain intact. As the illness progresses, however, the old as well as the new memories gradually disappear until even loved ones are no longer recognized. The fear of Alzheimer's stems not so much from anticipated physical pain and suffering but rather from the inexorable loss of a lifetime of memories that make up a person's very identity. Unfortunately, the computer analogy breaks down: one cannot simply reboot the human brain and reload the files and programs. The problem is that Alzheimer's does not only erase information; it destroys the very hardware of the brain, which is composed of more than 100 billion nerve cells (neurons), with 100 trillion connections among them. Most current medications for Alzheimer's take advantage of the fact that many of the neurons lost to the disease release a type of chemical communicator (or neurotransmitter) called acetylcholine. Because these medicines block an enzyme responsible for the normal decomposition of acetylcholine, they increase the levels of this otherwise depleted neurotransmitter. The result is stimulation of neurons and clearer thinking, but these drugs typically become ineffective within six months to a year because they cannot stop the relentless devastation of neurons. Another medication, called memantine, appears to slow the cognitive decline in patients with moderate to severe Alzheimer's by blocking excessive activity of a different neurotransmitter (glutamate), but investigators have not yet determined whether the drug's effects last more than a year. © 1996-2006 Scientific American, Inc.

Keyword: Alzheimers
Link ID: 8894 - Posted: 06.24.2010

BETHESDA, MD. (May 9, 2006) – Put a mouse or a rat under stress and what does it do? It stops eating. Humans should be so lucky. When people suffer nontraumatic stress they often head for the refrigerator, producing unhealthy extra pounds. When Syrian hamsters, which are normally solitary, are placed in a group-living situation, they also gain weight. So scientists at the Center for Behavioral Neuroscience at Georgia State University are using hamsters as a model for human stress-induced obesity. They want to begin unraveling the complex factors that lead people to eat when under stress and hope that the information can eventually be used to block appetites under this common scenario. The study, "Social defeat increases food intake, body mass, and adiposity in Syrian hamsters," by Michelle T. Foster, Matia B. Solomon, Kim L. Huhman and Timothy J. Bartness, Georgia State University, Atlanta, appears in the May issue of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology published by The American Physiological Society. In the study, the researchers look at nontraumatic stress -- the stress we experience in everyday life, such as getting stuck in traffic or trying to complete a major project at work. It is distinct from traumatic stress, such as suffering the death of a loved one. Traumatic stress typically dulls the human appetite, said Bartness, the study's senior researcher and an authority on obesity.

Keyword: Stress; Obesity
Link ID: 8893 - Posted: 06.24.2010

Michael Hopkin We are not the only animals to give ourselves names, says research on bottlenose dolphins. The dolphins' distinctive whistles may function as individual calling cards, allowing them to recognize each other and even refer to others by name. The research reveals that bottlenose dolphins (Tursiops truncatus) each have their own personalized whistle, which is recognized by other dolphins even from a synthetic version played through a speaker. This suggests that the creatures recognize these as names in their own right, rather than identifying individuals based simply on the sound quality of their voice. The dolphins have also been heard using each others' names in their 'conversation' — meaning that they may be able to call their comrades during social interactions. The calls may be used to bind groups together in the wild where individuals cannot always see each other, or to coordinate their delicately complex hunting manoeuvres. The effect was revealed in bottlenose dolphins living at in Sarasota Bay, Florida. The individual whistles of these dolphins are well known, as they have been involved in capture and recording studies since 1975. Researchers created artificial versions of specific dolphins' signature calls and played them to other dolphins from the group. Dolphins were more likely to turn towards the speaker if it was playing the call of a close relative, rather than an unrelated dolphin, the team reports in Proceedings of the National Academy of Sciences1. ©2006 Nature Publishing Group

Keyword: Language
Link ID: 8892 - Posted: 06.24.2010

Helen Pearson Autistic patients may lack the ability to daydream normally, say researchers who have found that these people's brains act differently when they are taking a break. Neuroscientists know that a certain network of brain regions fires up when our minds wander, and that this is important for pondering and reminiscing about ourselves, others and our emotions. Other studies have hinted that autistic patients, who have learning and social problems, might have abnormalities in this region but the details have been unclear. To pin down whether autism is related to these brain changes, Daniel Kennedy of the University of California at San Diego, La Jolla, and his colleagues studied 15 adults with some form of autism and 14 healthy controls. The team used functional magnetic resonance imaging (fMRI) to scan the 'daydreaming' regions, which lie in the middle of the brain. In healthy people, these spots become active when the brain is resting — and dampen down when the brain is working hard at a mental puzzle, the researchers confirmed. They also showed that part of the network revs up when participants read emotional words, such as 'murder' or 'blood', compared with bland ones such as 'table'. But the brains of autistic patients revealed a different picture. Their daydreaming network seemed permanently dampened; it did not show increased activity during rest and was not roused by emotional words. ©2006 Nature Publishing Group

Keyword: Autism
Link ID: 8891 - Posted: 06.24.2010

Alison Abbott Researchers have concluded that a gene responsible for most cases of hereditary deafness may have an unexpected benefit: it may protect you from infection. Stella Man, a member of David Kelsell's team at Queen Mary, University of London, spoke at the European Society of Human Genetics meeting in Amsterdam today, 8 May. She announced that the Cx26 protein encoded by a deafness gene might help wounds to heal. Faster healing should help to prevent infection, for example by limiting bacteria's access to the blood after surgery, she says. "It's speculation, but maybe the Cx26 deafness mutations have been selected owing to their beneficial effects on wounds." Kelsell identified the link between the Cx26 gene and deafness almost a decade ago1. Mutations of the gene are surprisingly common in all populations, from Africa to Europe and Asia, he says, but cause deafness only in those who inherit a mutated gene from both parents. A high frequency of mutation in any gene implies that there may be an evolutionary benefit for carriers. "It is well known that various genetic mutations that cause sickness in particular geographical areas sometimes also protect against local diseases, so there is a trade-off," says Kelsell. ©2006 Nature Publishing Group

Keyword: Hearing; Genes & Behavior
Link ID: 8890 - Posted: 06.24.2010

Patrick Barry Lesbian and heterosexual women respond differently to specific human odours, a brain-scanning study has found. The homosexual women showed similar brain activity to heterosexual men when they inhaled certain chemicals, which may be pheromones, the researchers say. "But our study can't answer questions of cause and effect," cautions lead researcher Ivanka Savic at the Karolinska Institute in Stockholm, Sweden. "We can't say whether the differences are because of pre-existing differences in their brains, or if past sexual experiences have conditioned their brains to respond differently." Savic and her colleagues asked 12 lesbian women and 12 heterosexual women to breathe concentrated samples of two steroids: EST, which is derived from oestrogen and found in the urine of pregnant women; and AND, which is derived from progesterone and found in men’s armpit sweat. Positron emission tomography (PET) scans revealed which regions of the women's brains responded to each chemical. When the heterosexual women smelled AND their brains showed activity in the anterior hypothalamus, a region of the brain thought to process sexual cues. But EST only produced activity in the olfactory region of their brains, the area that processes smells. The lesbians, however, only showed activity in the olfactory region whichever odour they smelled. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior
Link ID: 8889 - Posted: 06.24.2010

A contraceptive pill also used to treat acne is being investigated over concern it may increase the risk of depression. The Medicines and Healthcare Products Regulatory Authority (MHRA) which licenses drugs has ordered the review into Dianette. The charity April (Adverse Psychiatric Reactions Information Link) submitted a dossier on the drug. April says it has details of more than 100 women who say they became seriously depressed after taking Dianette. Dianette is licensed as a hormone treatment for severe acne, but only in cases where other treatments, such as oral antibiotics, have not worked. It is also an effective contraceptive, but doctors have been warned that they should not prescribe it solely for that purpose because it has a higher risk of blood clots than other similar combination pills. Women who take it are supposed to stop within three or four months of their skin problems clearing up. However, April says that it knows of some women who have been taking the drug for years. The manufacturer's information leaflet does warn that one possible side effect of taking the drug is "mild depression". Millie Kieve, who runs April, said it was clear that this was an under-statement. She said: "The doctor should warn these girls that if they are depressed, it could be Dianette, instead of putting them on antidepressants." Ms Kieve said she had been told by the MHRA was particularly concerned by the charity's evidence that doctors were continuing to prescribe Dianette solely as a contraceptive. The MHRA said it was hoped the findings of its review would be submitted to its expert advisory group on medicines for women's health at the end of May. The authority granted a licence to an identical pill called Clairette in March - but said there was no reason at the time not to. (C)BBC

Keyword: Depression; Hormones & Behavior
Link ID: 8888 - Posted: 05.08.2006

Parkinson's disease may trigger symptoms by crippling the key energy-producing "boiler room" of brain cells, research suggests. Two studies by US and Korean scientists focused on a mutant protein implicated in inherited Parkinson's. In tests on fruit flies, they found it disabled energy-producing cell structures called mitochondria, damaging cells controlling movement. The research is published online by the journal Nature. Previous research has established that an inherited form of early-onset Parkinson's - autosomal recessive juvenile parkinsonism (AR-JP) - is caused by mutations in a gene called PINK1. The researchers, from the University of California in Los Angeles and the Korea Advanced Institute of Science and Technology, explored the effect on the equivalent gene in the fruit fly, Drosophila. Flies with a mutant form of the gene suffered defects in the mitochondria. This appeared to cause serious damage to muscle cells, which led to movement problems. It also appeared to lead to trigger degeneration of cells that transport a key chemical, dopamine, around the brain. Parkinson's has been linked to a shortage of dopamine, which is known to play a key role in the co-ordination of movement. Both muscle cells and dopamine-transporting brain cells consume large amounts of energy, and thus are more reliant than most on healthy mitochondria. The researchers also produced evidence suggesting that the PINK1 protein has a knock-on effect on another molecule - Parkin - which has also been implicated in Parkinson's. They suspect that the two proteins both play an important role in keeping the mitochondria healthy. (C)BBC

Keyword: Parkinsons
Link ID: 8887 - Posted: 05.08.2006

MADISON - In a painstaking set of experiments in overweight mice, scientists from the University of Wisconsin-Madison have discovered a gene that appears to play an important role in the onset of type 2 diabetes. The finding is important because it provides evidence that the same gene in humans could provide clinicians with a powerful tool to determine the likelihood that some individuals will acquire the condition. Moreover, the finding that the gene works through a pathway not generally studied in the context of diabetes, suggests new avenues to explore in the search for new drugs to treat or prevent the disease, says Alan Attie, a UW-Madison professor of biochemistry and the senior author of the study published this week (May 7) in the journal Nature Genetics. Type 2 diabetes is the most common form of the condition in the United States, with an estimated 16 million Americans afflicted with the disease. It is caused by an inability of the pancreas to produce enough insulin, or by the body's reduced ability to respond to insulin, or both. Insulin is necessary for the body to properly utilize sugar. Often, the development of type 2 diabetes is caused by obesity. Obese individuals tend to have insulin resistance; that is, it takes more insulin for the body to respond normally. Type 2 diabetes occurs when the pancreas is unable to manufacture enough insulin to compensate for the body's increased demand for the hormone, which it does by growing more insulin-producing beta cells or by ramping up insulin secretion.

Keyword: Obesity; Genes & Behavior
Link ID: 8886 - Posted: 05.08.2006

Bruce Bower Bones from a spinal column discovered at a nearly 1.8-million-year-old site in central Asia support the controversial possibility that ancient human ancestors spoke to one another. Excavations in 2005 at Dmanisi, Georgia, yielded five vertebrae from a Homo erectus individual, says anthropologist Marc R. Meyer of the University of Pennsylvania in Philadelphia. The finds occurred in previously dated sediment that has yielded several skulls now attributed to H. erectus (SN: 5/13/00, p. 308: Available to subscribers at http://www.sciencenews.org/articles/20000513/fob1.asp). The new discoveries represent the oldest known vertebrae for the genus Homo, Meyer announced last week at the annual meeting of the Paleoanthropology Society in San Juan, Puerto Rico. The fossils consist of one lumbar, two thoracic, and two cervical vertebrae. Meyer and his colleagues—David Lordkipanidze and Abesalom Vekua, both of the Georgian State Museum in Tbilisi—compared the size, shape, and volume of the Dmanisi vertebrae with more than 2,200 corresponding bones from people, chimpanzees, and gorillas. Copyright ©2006 Science Service.

Keyword: Evolution
Link ID: 8885 - Posted: 06.24.2010

By Robert F. Service Magnetic Resonance Imaging (MRI) machines' knack for peering at soft tissue deep within the body has made them one of the most popular imaging tools. But MRI isn't perfect. It works by beaming radiofrequency pulses into a patient and tracking how this radiation affects the magnetic behavior of tissues. But those pulses must be carefully controlled to prevent them from overheating tissue and injuring patients. Now, a new study could pave the way to a new form of radiofrequency-free MRI scans that would offer several advantages. MRI owes its success to the magnetic behavior of the protons in hydrogen atoms within the body. Those protons have a magnetic moment, which makes them behave essentially like compass needles. To create an image, MRI machines place patients in a strong magnetic field, which causes the protons in the body to align their magnetic compasses with that field. Technicians then send in precisely tuned pulses of radiofrequency energy that knocks some of those compasses out of alignment. By tracking how the needles return to equilibrium, researchers can infer their distribution and thus the makeup of the tissue. But Norbert Müller of Johannes Kepler University in Linz, Austria, and Alexej Jerschow of New York University in New York City wanted to see if they could do away with the need for radiofrequency pulses. © 2006 American Association for the Advancement of Science.

Keyword: Brain imaging
Link ID: 8884 - Posted: 06.24.2010

BOSTON--Scientists have long known that brains need neural activity to mature and that sensory input is most important during a specific window of time called the "critical period" when the brain is primed for aggressive learning. Vision, hearing and touch all develop during such critical periods, while other senses, such as the olfactory system, maintain lifelong plasticity. The visual system provides an exemplary model for studying developmental plasticity, however, because of the pioneering work of Nobel prize-winning HMS researchers David Hubel and Torsten Wiesel describing the visual system's structure, prerequisite knowledge for investigating its flexibility. Although visual plasticity has been studied for over 40 years, exactly how sensory experience interacts with the built-in machinery that permits the brain to change its circuits is only beginning to be understood. A new study focusing on the molecular roots of plasticity has found that visual stimulus turns up the expression of some genes and turns down the expression of others, somewhat like a conductor cueing the members of an orchestra. The study also found that during different stages of life in rodents, distinct sets of genes spring into action in response to visual input. These gene sets may work in concert to allow synapses and neural circuits to respond to visual activity and shape the brain, reports the May issue of Nature Neuroscience.

Keyword: Development of the Brain; Vision
Link ID: 8883 - Posted: 05.06.2006

BUFFALO, N.Y. -- When trying to lie your way through any situation, keep a tight rein on your zygo maticus major and your orbicularis oculi. They'll give you away faster than a snitch. So says social psychologist Mark Frank, whose revolutionary research on human facial expressions in situations of high stakes deception debunks myths that have permeated police and security training for decades. His work has come to be recognized by security officials in the U.S. and abroad as very useful tool in the identification and interrogation of terrorism suspects. By applying computer technology to the emotion-driven nature of nonverbal communication, Frank, a professor of communication in the School of Informatics at the University at Buffalo, has devised methods to recognize and accurately read the conscious and unconscious behavioral cues that suggest deceit. His research already is employed by investigative bodies around the world and, Frank says, "It can be applied to the training of security checkpoint personnel to help them identify and decode 'hot spots,' the subtle conversational cues and fleeting flashes of expression that betray buried emotions or suggest lines of additional inquiry." © 2006 University at Buffalo.

Keyword: Emotions; Stress
Link ID: 8882 - Posted: 06.24.2010

By Shankar Vedantam, Washington Post Staff Writer About 300,000 American children have been diagnosed as having autism, according to the first comprehensive national surveys of the developmental disorder. Boys were four times more likely than girls to have the disorder, which is characterized by verbal, social and emotional problems. White families with higher incomes were also more likely to report having children with the disorder, a fact that federal experts said probably reflected unequal access to medical services. The new data came in two surveys released yesterday by researchers at the Centers for Disease Control and Prevention, who said the numbers matched the range found by earlier studies that looked at smaller groups of people. Autism has been dogged by controversy for more than a decade after what appeared to be a sharp increase in diagnoses in the 1990s. Many experts believe the increase reflects changes in diagnostic criteria adopted in 1994, increased public awareness of the problem, and the difficulties in telling apart a number of overlapping conditions that fall under an umbrella known as autism spectrum disorders. Some advocates have blamed a mercury-based preservative in children's vaccines, even though repeated analyses have failed to confirm a link. The new surveys show that Hispanics have a much lower autism rate than whites, but experts said that this probably reflected differences in access to care. © 2006 The Washington Post Company

Keyword: Autism
Link ID: 8881 - Posted: 06.24.2010

Ian Hacking Autism is devastating – to the family. Children can be born with all manner of problems. Some begin life in great pain that can never be relieved, but at least there is a child there. An autistic child – and here I am talking about what’s known as core autism – is somehow not there. ‘Nobody Nowhere’, as the title of Donna Williams’s autobiography (1992) has it. Very often physically healthy (though there is a high incidence of other problems) he – and it is usually he – just does not respond. It is not merely that he does not learn to speak until years after his peers, and then inadequately. He has no affect; he never snuggles. He is obsessed with things and order, but does not play with toys in any recognisable way, and certainly does not play with other children. He mercilessly repeats a few things you say. With no comprehension. He has violent tantrums, not the usual sort of thing, but screaming, hitting, biting, smashing. This alternates with a placid gentleness, maybe even a smile – but not really for you. Serious Down’s syndrome is pretty bad too, but despite all the difficulties, physical and mental, there is a loving little child there. That is what is so dreadful about core autism: your child is an alien. Parents who guide their autistic infant through to adulthood, who create a human being who can be loving, who can to some extent compensate for his deficits, who can find some dignity and maybe a modest type of respected work – they are, in my opinion, heroes. Many parents will be angry with what I have just said. ‘It is not like that at all. Peter is the most lovable little boy. copyright © LRB Ltd, 1997-2006

Keyword: Autism
Link ID: 8880 - Posted: 06.24.2010

Helen Pearson The paralysing dread one feels before an injection or tooth extraction fires up some of the same brain regions involved in feeling pain itself, say researchers who subjected plucky volunteers to electric shocks. Their discovery supports the idea that distraction could ease a nasty wait. Many people prefer to get an awful event over with sooner rather than later. But neuroscientists didn't know what was going on in our brains during this period of suspense, or exactly why we make this decision. Gregory Berns of Emory University School of Medicine, Atlanta, Georgia, and his co-workers scanned the brains of 32 people while they waited for an electric shock to the foot, much like a spark from static electricity. During the experiment, people were offered a series of choices of the intensity of shock they would receive and when they would receive it. When offered the choice of 'sooner' or 'later' for shocks of equal voltage, almost all the participants wanted to get the shock over with straight away. The team called these people 'mild dreaders'. But nine people dreaded the shock so much that they chose a stronger blast sooner over a milder one later on. This group earned the label 'extreme dreaders'. Berns says that most people could probably if they were an extreme dreader from their everyday experience. ©2006 Nature Publishing Group

Keyword: Emotions; Brain imaging
Link ID: 8879 - Posted: 06.24.2010

Scientists have created "autistic" mice by deleting a single gene in key parts of the brain. US researchers found the mice had traits such as poor social interaction and high sensitivity. They say the findings, published in the Neuron, could point the way to better understanding of the causes of autism. One UK expert said the findings were interesting, but needed much more work before they could be applied to humans. An autistic spectrum disorder is a developmental disability that affects the way a person communicates and interacts with those around them. Such disorders tend to emerge in childhood, and affect about 90 in 10,000 people. Boys tend to be affected more often than girls. The University of Texas team looked at mice where the Pten gene - which has already been linked to other brain disorders - was deleted in the mature nerve cells in the cerebral cortex and hippocampus areas of the brain. These regions are associated with higher brain function such as learning and memory. The mice behaved in a number of socially abnormal ways, compared to another group of mice from the same litter. The genetically altered mice were socially less skilled, being far less likely to be curious about new animals coming into the cage. They also showed the same level of interest in an empty cage and in one containing another mouse - mirroring the behaviour of children with autistic spectrum disorders. (C)BBC

Keyword: Autism
Link ID: 8878 - Posted: 05.04.2006

Male tropical túngara frogs have evolved masses on their vocal cords that help them woo females with complex calls, show scientists working at the Smithsonian Tropical Research Institute (STRI) in Panama. Dr. Mike Ryan, Clark Hubbs Regents Professor of integrative biology at The University of Texas at Austin, Dr. Marcos Gridi-Papp, a post-doctoral scholar in physiological sciences at UCLA, and the late Dr. Stan Rand, of STRI, published their findings in the May 4 issue of Nature. Males of the túngara frog, Physalaemus pustulosus, attract females by singing out "whine chuck chuck" calls in wetlands and puddles during the rainy season. The males may only produce whines, but females are more attracted to males that also produce chucks. The scientists surgically removed the fibrous masses in the males' larynx and found that they could no longer produce the "chuck". The frogs produced a normal whine and attempted to add chucks to it, but the sounds that they added lacked the distinctive pattern of the chuck. "By removing the structure within the larynx, we eliminated the ability of a frog to produce a complex call," says Ryan. "Now we know that there is a structure associated with a single syllable of the call."

Keyword: Language; Evolution
Link ID: 8877 - Posted: 05.04.2006

By Kelli Whitlock Burton Give a mouse more room and a few toys, and good things happen. New neurons sprout in the hippocampus, while spatial memory improves and anxiety eases. As tempting as it might be to tie the new neurons to the behavioral changes, a new study finds no link between them. The results contradict a popular assumption among scientists that new neurons in the hippocampus contribute to the cognitive boost that comes with a more stimulating environment. The notion that two parts of the brain--the hippocampus and olfactory bulb--continue to produce new neurons into adulthood has been widely accepted since the late 1990s. But just what role those new cells play in cognitive function remains a mystery. Recent studies have found that animals housed in larger cages with opportunities for exercise and social interaction generate more new neurons in the hippocampus than do animals in more cramped quarters with no playmates. Scientists in the lab of Columbia University neurobiologist René Hen hoped to find the link between hippocampal neurogenesis and certain behaviors such as learning and memory that involve the hippocampus. Hen's team zapped mice with a focused dose of radiation to halt neurogenesis in a portion of the animals' hippocampuses. They then placed half the animals in regular cages and half in enhanced environments for 6 weeks before testing their anxiety and spatial memory. To the researchers' surprise, the animals with better accommodations had improved spatial memory skills and were less anxious than mice in smaller confines, despite not having any new neurons in their hippocampuses. © 2006 American Association for the Advancement of Science.

Keyword: Learning & Memory; Neurogenesis
Link ID: 8876 - Posted: 06.24.2010

The prospect of a paycheck, good grade, or promotion wonderfully concentrates the mind, and researchers have now identified the brain circuitry responsible for such reward-motivated learning. In an article in the May 4, 2006, Neuron, Alison Adcock and colleagues report brain-scanning studies in humans that reveal how specific reward-related brain regions "alert" the brain's learning and memory regions to promote memory formation. In their studies, the researchers asked volunteers to participate in two types of reward-related tasks as they scanned the subjects' brains using functional magnetic resonance imaging. In this technique, harmless magnetic fields and radio waves are used to detect regions of higher blood flow in the brain, which reflects higher activity. In the first task, the researchers aimed at identifying the region involved in anticipating rewards. This task involved presenting the subjects with such symbols as circles or squares that indicated an amount of money the subjects could gain or lose--from no money to $5--by rapidly responding to a subsequently presented target by pressing a button. The subjects were notified immediately whether they had received the reward. The researchers found that reward anticipation activated specific brain structures in the "mesolimbic" region involved in the processing of emotions.

Keyword: Learning & Memory
Link ID: 8875 - Posted: 05.04.2006