all cognitive neuroscience stories

Scientists isolate a toxic key to Alzheimer's disease in human brains

404132862 — Mon, 23 Jun 2008 20:23:16 -0400

Scientists have long questioned whether the abundant amounts of amyloid plaques found in the brains of patients with Alzheimer's actually caused the neurological disease or were a by-product of its progress. Now, using new research techniques, scientists have shown that a two-molecule aggregate (or dimer) of beta-amyloid protein fragments may play a role in initiating the disease.

Neuroimaging fails to demonstrate ESP is real

404132862 — Thu, 03 Jan 2008 16:00:49 -0500

Psychologists at Harvard University have developed a new method to study extrasensory perception that, they argue, can resolve the century-old debate over its existence. According to the authors, their study not only illustrates a new method for studying such phenomena, but also provides the strongest evidence yet
obtained against the existence of extrasensory perception, or ESP.

Transitivity, the orbitofrontal cortex, and neuroeconomics

404132862 — Mon, 10 Dec 2007 10:58:28 -0500

You study the menu at a restaurant and decide to order the steak rather than the salmon. But when the waiter tells you about the lobster special, you decide lobster trumps steak. Without reconsidering the salmon, you place your order — all because of a trait called "transitivity."

Steven Pinker’s ‘Ideas on the Fringe’

jake — Mon, 29 Oct 2007 11:29:15 -0400

Not long ago, Steven Pinker appeared on “The Colbert Report.” He managed to explain the functioning of the human brain to Stephen Colbert in only five words: “Brain cells fire in patterns.”

Study shows importance of sleep for optimal memory functioning

Wed, 11 Jul 2007 11:46:32 -0400

Harvard researchers have tracked fatigue's footsteps on the human brain, showing that sleeplessness impairs the ability to learn new information and that abnormal brain function, not reduced alertness, is the cause.

The study, released in the journal Nature Neuroscience, adds a new wrinkle to the unfolding story of the importance of sleep for memory function and builds on earlier studies that show that sleep deprivation after an event also impairs memory formation.

The study found that student volunteers who had been awake for 35 hours before viewing images performed an average of 19 percent worse remembering those images two days later, after catching up on their sleep.

Bad times make for more accurate memories

70652986 — Mon, 26 Mar 2007 06:27:22 -0400

Pleasurable experiences are more fun to relive than negative ones, but a new study by psychologists at Harvard University reveals that memories of good times can be less accurate than those of bad times.

Not only that, a person with a positive memory is more likely to be more confident of her or his distorted memory than someone who has a negative memory of the same event.

Take the beating that the Boston Red Sox gave the New York Yankees when the Sox won the American League playoff series in October 2004. That's the event the Harvard researchers used to probe the effects of emotion on memory.

Elizabeth Kensinger, a postdoctoral fellow, worked with Daniel Schacter, William R. Kenan Jr. Professor of Psychology, to recruit 76 men and women, ages 18-35, who had watched the contest. Some were avid Red Sox fans, some were rabid Yankees fans, and some professed no strong feelings about the outcome. All of them filled out questionnaires within six days of the game, then again after a 23- to 27-week delay. Answers were scored on quantity and consistency of information, confidence in the memory, and its vividness.

Some participants reported a piece of information entirely differently on the two surveys. In those cases, they got a constancy score of zero. Emotion and vividness were rated on a scale of 1 to 7. For emotions, lower numbers indicated negative feelings, higher numbers denoted positive feelings. For example, Red Sox fans gave their memories ratings of 5.5 or higher; Yankees rooters, 2.5 or lower. None of the participants reported a history of psychiatric or nervous disorders.

Studies like this, which compare the emotions and memories associated with well-known happenings, are rare. "To our knowledge, only one prior study examined the effect of positive versus negative emotions on the vividness and accuracy of memory for a public event," notes Kensinger. The investigators asked men and women about the trial that cleared O.J. Simpson of the murder of his wife. "Those who were happy about the verdict could not discriminate true from false details of the event any better than those unhappy about it," adds Schacter. "Despite this, the happy group believed they remembered the event more vividly. These results are consistent with laboratory tests showing that positive mood can lead to an increased probability of memory errors."

Monkey see, monkey infer

70652986 — Mon, 26 Mar 2007 06:26:58 -0400

Monkeys keep turning out to be smarter than people think they are. Researchers have shown that they can count to four and are aware of differences between languages like Dutch and Japanese, even though they don't known what is being said. Now, Harvard psychologists find that monkeys can draw correct conclusions about novel situations. For example, shown a white towel that turns blue, a blue knife, and a glass of blue paint, they can figure out that the paint, not the knife, is responsible for the change in color.

"Our studies reveal a striking continuity between humans and monkeys in their capacity to draw causal inferences without the help of familiarity with the events or situation," says Marc Hauser, a Harvard professor of psychology. "This ability highlights the richness of the monkey mind in terms of its understanding of the material world."

Hauser has been working with a colony of free-ranging rhesus monkeys on an island off Puerto Rico for many years. He and Bailey Spaulding, formerly a student of his, tested individual adult males and females of the colony on their ability to figure out cause and effect in unfamiliar situations.

In their experiments, they used a glass of water and a knife along with a whole apple and an apple cut in half. The knife can halve the apple, but the water can't. Do the monkeys grasp this?

In one set of tests the monkeys saw a glass of water and two whole apples. Then they viewed a knife being lowered and the apple cut in half. These are two perfectly plausible situations. Next, they saw the glass of water and two halves of an apple. Following this, a knife was lowered, and two apple halves seemingly became a whole apple.

To a human, even an infant who had never seen such things before, the last two apparent happenings would never really happen. Can monkeys infer the same outcomes? Evidently, the answer is "yes." They looked longer when a glass of water appeared to cut the apple than when a knife seemed to do the same. The longer look signaled disbelief.

Attention shoppers: Researchers find neurons that encode the value of different goods

70652986 — Mon, 26 Mar 2007 06:26:35 -0400

Researchers at Harvard Medical School report in the April 23, 2006 issue of Nature that they have identified neurons that encode the values that subjects assign to different items. The activity of these neurons might facilitate the process of decision-making that occurs when someone chooses between different goods.

"We have long known that different neurons in various parts of the brain respond to separate attributes, such as quantity, color, and taste. But when we make a choice, for example, between different foods, we combine all these attributes -- we assign a value to each available item," says Camillo Padoa-Schioppa, PhD, HMS research fellow in neurobiology and lead author of the paper. "The neurons we have identified encode the value individuals assign to the available items when they make choices based on subjective preferences, a behavior called 'economic choice.'"

Everyday examples of economic choice include choosing between working and earning more or enjoying more leisure time, or choosing to invest in bonds or in stocks. Such choices have long been studied by economists and psychologists. In particular, research in behavioral economics shows that in numerous circumstances, peoples' choices violate the criteria of economic rationality. This motivates a currently growing interest for the neural bases of economic choice -- an emerging field called "neuroeconomics." In general, it is believed that economic choice involves assigning values to available options. However, the underlying brain mechanisms are not well understood.

In the study, Padoa-Schioppa and John Assad, PhD, HMS associate professor of neurobiology, found a population of neurons located in the orbitofrontal cortex (OFC) that assigns values to different goods on a common value scale. Assigning values on a common scale allows comparing goods, like apples and oranges, that otherwise lack a natural basis for comparison.

Ancient molecules guide new synapse growth

70652986 — Mon, 26 Mar 2007 06:25:20 -0400

Recent research has shifted the understanding of a group of specialized molecules in the extracellular matrix, recasting them from scaffolding only to key cue-providers that help guide the formation of the nervous system.

The findings are reported in the Feb. 16, 2006 Neuron by Misao Higashi, April Duckworth, Aurnab Ghose, Thomas Schwarz, Alan Tenney, David Van Vactor, John Flanagan and other colleagues. The team focused on two of these heparan sulfate proteoglycans and found that through a certain receptor, they compete to accomplish different tasks in synapse formation. The study suggests a preliminary model for a molecular synapse-forming mechanism.

Long-term memory controlled by molecular pathway at synapses

70652986 — Mon, 26 Mar 2007 06:23:41 -0400

Even for a fruit fly, learning and memory are important adaptive tools that facilitate survival in the environment. A fly can learn to avoid what may do it harm, such as a flyswatter, or in the laboratory, an electric shock that happens when it smells a certain odor.

Now Harvard University biologists have identified a molecular pathway active in neurons that interacts with RNA to regulate the formation of long-term memory in fruit flies. The same pathway is also found at mammalian synapses, and could eventually present a target for new therapeutics to treat human memory loss.

"It has been known for some time that learning and long-term memory require synthesis of new proteins, but exactly how protein synthesis activity relates to memory creation and storage has not been clear," says Sam Kunes, professor of molecular and cellular biology in Harvard's Faculty of Arts and Sciences. "We have been able to monitor, for the first time, the synthesis of protein at the synapses between neurons as an animal learns, and we found a biochemical pathway that determines if and where this protein synthesis happens. This pathway, called RISC, interacts with RNA at synapses to facilitate the protein synthesis associated with forming a stable memory. In fruit flies, at least, this process makes the difference between remembering something for an hour and remembering it for a day or more."

Together with lead author Shovon Ashraf, a postdoctoral researcher in Harvard's Department of Molecular and Cellular Biology, and Anna McLoon '04 and Sarah Sclarsic '06, Kunes found that messenger RNA (mRNA) - a genetic photocopy that conveys information from DNA to a cell's translation machinery - is transported to synapses as a memory begins to form. This mRNA transport, and the protein synthesis that follows, are facilitated by components of the RISC pathway, which use very short RNA molecules called microRNAs to guide their activity. One of these RISC proteins, called Armitage, appears to be a critical regulatory molecule in long-lasting memory formation, and has to be destroyed at particular synapses in order for protein synthesis to occur there.

The findings were presented on the Web site of the journal Cell.

Waking up to how we sleep and dream

70652986 — Mon, 26 Mar 2007 05:42:25 -0400

The Oct. 27, 2005 issue of the prestigious science journal Nature devotes almost 40 pages to bringing readers up-to-date on what happens during sleep. Three of the articles are by Harvard Medical School scientists who discuss such things as an on-off sleep switch, and learning while we sleep.

Clifford Saper, James Jackson Putnam Professor of Neurology and Neuroscience, and his colleagues at Beth Israel Deaconess Medical Center study key nerve circuits that switch us from waking to sleeping and back. Two small clusters of nerve cells in the hypothalamus, a cherry-size area behind the eyes, shut down our arousal circuits when we sleep. The switch is turned back on by the time of day and the length of time spent awake before going to bed.

Study: No psychological or cognitive deficits from peyote

70652986 — Mon, 26 Mar 2007 06:22:45 -0400

Researchers at Harvard-affiliated McLean Hospital report that Native Americans who use the hallucinogen peyote regularly in connection with religious ceremonies show no evidence of brain damage or psychological problems.

In fact, members of the Navajo tribe who regularly use peyote actually scored significantly better on several measures of overall mental health than did subjects from the same tribe who were not members of the religious group and did not use the hallucinogen, according to a paper published in the Nov. 4, 2005 issue of Biological Psychiatry.

"We found no evidence that these Native Americans had residual neurocognitive problems. Despite lifelong participation in the peyote church, they performed just as well on mental tests as those who had never used peyote,'' said the study's first author John Halpern, MD, of McLean Hospital's Biological Psychiatry Laboratory. The study was funded, in part, by the National Institute on Drug Abuse.

Beyond that, the peyote users scored better on several measures of the Rand Mental Health Inventory (RMHI), a test used to diagnose psychological problems and determine overall mental health, he said. Among the RMHI scales are measures of anxiety, depression, loss of behavioral or emotional control, and psychological distress. Halpern emphasized that the better scores among peyote users were not necessarily attributable to the use of peyote itself, but more likely due to the social and psychological benefits of being members of the Native American Church community.

Alien abduction claims explained

70652986 — Mon, 26 Mar 2007 06:21:57 -0400

Abduction stories are strikingly similar. Victims wake up and find themselves paralyzed, unable to move or cry out for help. They see flashing lights and hear buzzing sounds. Electric sensations zing through their bodies, which may rise up in levitation. Aliens with wrap-around eyes, gray or green skin, lacking hair or noses, approach. The abductee's heart pounds violently. There's lots of probing in the alien ship. Instruments are inserted in their noses, navels, or other orifices. It's painful. Sometimes sexual intercourse occurs.

Then it's over, after seconds or minutes.

Brain chemical serotonin involved in early embryo patterning

70652986 — Mon, 26 Mar 2007 06:18:11 -0400

A study published in the May 10, 2005, Current Biology has ramifications for neuroscience, developmental genetics, evolutionary biology and, possibly, human teratology (a branch of pathology and embryology concerned with abnormal development and congenital malformations). Among other results, the study, which was carried on frog and chick embryos: • Provides the first molecular support for the idea that serotonin is utilized as a large-scale left-right patterning mechanism, thus offering new insight into the basis of position of the heart and other asymmetric, visceral organs. • Identifies a possible novel serotonin signaling pathway, providing evidence that serotonin can signal inside the cell. If also found in mammals, such signaling, which may be important in brain functioning, would suggest numerous new roles and possible targets for serotonin-related drugs like the selective serotonin reuptake inhibitors (SSRI antidepressants such as Prozac and Zoloft) or the monoamine oxidase inhibitors (MAOIs). • Could lead to a greater understanding of potential health risks from drug families that target the serotonin pathway in human patients. • Sheds light on the evolutionary origin of a crucial neurological control system, suggesting that neuronal synapses using serotonin as a neurotransmitter may have arisen through the adaptation of ancient, fundamental cell-cell signals to a new purpose as nervous systems evolved. The team was led by principal investigator Michael Levin, assistant professor at Harvard Medical School. The study was funded by the National Science Foundation and the American Heart Association.

One alcoholic drink per day improves cognitive function among older women

70652986 — Mon, 26 Mar 2007 06:19:51 -0400

According to the study's senior author, BWH's Francine Grodstein, Sc.D., "Much evidence has demonstrated the heart benefits of light alcohol drinking, but less research has focused on cognitive functioning. While we all continue to recommend exercising caution when consuming any type of alcohol, our study suggests that moderate consumption might provide older women some cognitive benefits."

Researchers reviewed data from 12,480 women, 70 to 81 years old, who participated in the Nurses' Health Study. They first collected alcohol consumption data as part of food-frequency questionnaires issued every few years between 1980 and 1998. Alcohol intake was measured in grams of beer, wine and liquor, with moderate consumption - one glass per day - defined as less than 15 grams per day. Then, from 1995-2002, women participated in telephone-based cognitive surveys in which general cognition and verbal memory and fluency were evaluated. Women who consumed less than 15 grams of alcohol per day - moderate drinkers - had better mean cognitive scores than nondrinkers. Researchers also found no significant difference in cognitive functioning among the nondrinkers and those who consumed more than one drink per day. Also, there did not seem to be any substantial difference in the effects of different forms of alcoholic beverages.

"Given our large study population, this body of research is now powerful enough to suggest continued research to ultimately better understand the impact moderate alcohol has on cognitive function," said HSPH's Meir Stampfer, M.D.