Biological Psychology Links

by Jessica Griggs IT'S a big skull. No, wait, it's two people under an arch. Hold on, it's a skull again. Two very different images can be perceived in the trick picture Blossom and Decay (see right). Now we are one step closer to working out how the brain spontaneously flips between such views, with the discovery of what may be the relevant brain region. The precise neural mechanism that provokes the brain to switch its view of a scene is unknown, but it is thought to play a major role in perception by acting as a sort of reality check, says Ryota Kanai of University College London. "We need a trigger to prompt possible different interpretations so that we don't get stuck with a potentially incorrect interpretation of the world." To find out which part of the brain might be involved, Kanai and colleagues asked 52 volunteers to watch a video of a revolving sphere and press a button when the rotation of the sphere appeared to change direction. Crucially, the sphere was not changing direction; it could simply be perceived to be rotating in either direction. How long each rotation-direction was perceived for was recorded and an average "switch rate" assigned to each of the volunteers. The team then used structural magnetic resonance imaging to search for active brain regions during this task. This pointed to the superior parietal lobes (SPL), two areas towards the back of the head known to control attention and process three-dimensional images. People whose cortex was thicker and better connected in this region had faster switch rates. © Copyright Reed Business Information Ltd.

by David Robson Can you tell a snake from a pretzel? Some can't – and their experiences are revealing how the brain builds up a coherent picture of the world AFTER her minor stroke, BP started to feel as if her eyes were playing tricks on her. TV shows became confusing: in one film, she was surprised to see a character reel as if punched by an invisible man. Sometimes BP would miss seeing things that were right before her eyes, causing her to bump into furniture or people. BP's stroke had damaged a key part of her visual system, giving rise to a rare disorder called simultanagnosia. This meant that she often saw just one object at a time. When looking at her place setting on the dinner table, for example, BP might see just a spoon, with everything else a blur (Brain, vol 114, p 1523). BP's problems are just one example of a group of disorders known collectively as visual agnosias, usually caused by some kind of brain damage. Another form results in people having trouble recognising and naming objects, as experienced by the agnosic immortalised in the title of Oliver Sacks's 1985 best-seller The Man Who Mistook His Wife for a Hat. Agnosias have become particularly interesting to neuroscientists in the past decade or so, as advances in brain scanning techniques have allowed them to close in on what's going on in the brain. This gives researchers a unique opportunity to work out how the brain normally makes sense of the world. "Humans are naturally so good at this, it's difficult to see our inner workings," says Marlene Behrmann, a psychologist who studies vision at Carnegie Mellon University in Pittsburgh, Pennsylvania. Cases like BP's are even shedding light on how our unconscious informs our conscious mind. "Agnosias allow us to adopt a reverse-engineering approach and infer how [the brain] would normally work," says Behrmann. © Copyright Reed Business Information Ltd

By Katherine Harmon Binge-shoppers and serial daters might perpetually be living at the whim of their latest impulse, and now research is getting to the biological basis of their seemingly random behavior. "Individuals vary widely in their capacity to deliberate on the potential consequences of their choices before they act," note the authors of a new study on the impulsive tendency. "Highly impulsive people frequently make rash, destructive decisions." Impulsivity has long been linked to the neurotransmitter dopamine, which is involved in learning and reward. And a new model helps to illuminate the connection between the two. The work is described in a study published online July 29 in Science. A team of researchers led by Joshua Buckholtz, a PhD candidate in neuroscience at Vanderbilt University, proposed that people who were more impulsive might have less active dopamine receptors in their midbrain but their brains would be more likely to fire off large quantities of the neurotransmitter when stimulated. To verify their hypothesis, the researchers used PET scans to watch the brains of 32 healthy and psychiatrically normal test subjects ages 18 to 35 (who had no history of substance abuse) while they were taking a classic test to measure impulsivity. Before the first testing round, subjects had taken a placebo pill, but before the second, they were given an oral dose of amphetamine, which can stimulate the brain's reward pathways, mobilizing dopamine. © 2010 Scientific American

By TARA PARKER-POPE Does your husband or wife constantly forget chores and lose track of the calendar? Do you sometimes feel that instead of living with a spouse, you’re raising another child? Your marriage may be suffering from attention deficit hyperactivity disorder. An A.D.H.D. marriage? It may sound like a punch line, but the idea that attention problems can take a toll on adult relationships is getting more attention from mental health experts. In a marriage, the common symptoms of the disorder — distraction, disorganization, forgetfulness — can easily be misinterpreted as laziness, selfishness and a lack of love and concern. Experts suggest that at least 4 percent of adults suffer from the disorder; that as many as half of all children with A.D.H.D. do not fully outgrow it and continue to struggle with symptoms as adults; and that many adults with the disorder never got the diagnosis as children. Adults with attention disorders often learn coping skills to help them stay organized and focused at work, but experts say many of them struggle at home, where their tendency to become distracted is a constant source of conflict. Some research suggests that these adults are twice as likely to be divorced; another study found high levels of distress in 60 percent of marriages where one spouse has the disorder. “Typically people don’t realize the A.D.H.D. is impacting their marriage because there’s been no talk about this at all,” said Melissa Orlov, author of the new book “The A.D.H.D. Effect on Marriage,” to be published in September. Copyright 2010 The New York Times Company

By JOHN TIERNEY At long last, the doodling daydreamer is getting some respect. In the past, daydreaming was often considered a failure of mental discipline, or worse. Freud labeled it infantile and neurotic. Psychology textbooks warned it could lead to psychosis. Neuroscientists complained that the rogue bursts of activity on brain scans kept interfering with their studies of more important mental functions. But now that researchers have been analyzing those stray thoughts, they’ve found daydreaming to be remarkably common — and often quite useful. A wandering mind can protect you from immediate perils and keep you on course toward long-term goals. Sometimes daydreaming is counterproductive, but sometimes it fosters creativity and helps you solve problems. Consider, for instance, these three words: eye, gown, basket. Can you think of another word that relates to all three? If not, don’t worry for now. By the time we get back to discussing the scientific significance of this puzzle, the answer might occur to you through the “incubation effect” as your mind wanders from the text of this article — and, yes, your mind is probably going to wander, no matter how brilliant the rest of this column is. Mind wandering, as psychologists define it, is a subcategory of daydreaming, which is the broad term for all stray thoughts and fantasies, including those moments you deliberately set aside to imagine yourself winning the lottery or accepting the Nobel. But when you’re trying to accomplish one thing and lapse into “task-unrelated thoughts,” that’s mind wandering. Copyright 2010 The New York Times Company

Even if you haven't taken the invisible gorilla test, you've probably heard of it. It consists of a short video of two teams of students moving around while they pass basketballs. The idea is to count the number of passes made by one team while ignoring those made by the other. Roughly half of those who take the test fail to notice a person dressed as a gorilla who strolls into the middle of the players and beats its chest at the camera. The viewers are concentrating so hard on counting the passes that they're blind to the unexpected, even though it is staring them in the face. This book is by the psychologists who devised that experiment (see Gorilla psychologists: Weird stuff in plain sight). Their aim is to show how easy it is to miss things that are right in front of us when we're not looking out for them, and how illusions and distorted beliefs lead us astray every day. They cover what they consider to be six of the most common intuitive errors: Some of these biases have been widely written about, but it is worth reading them again here for the clarity with which Chris Chabris and Dan Simons explain them and their talent for making them relevant to everyday situations. They demonstrate, for example, how over-confidence in one's abilities can be hilarious in a talent show contestant or an incompetent criminal caught on camera, but worrying when it dissuades other members of a group from sharing their own - less confidently held but nonetheless important - opinions. And such over-confidence can be positively dangerous in a witness whose apparently credible evidence is given undue weight by jurors or police. © Copyright Reed Business Information Ltd.

Neuroscientists at NYU and Harvard identify cells in the hippocampus that signal new memory formation Neuroscientists at NYU and Harvard have identified how the brain’s hippocampus helps us learn and remember the sights, sounds and smells that make up our long-term memory for the facts and events, termed declarative memory. By studying the activity of neurons of the hippocampus, the scientists have illuminated how the brain signals the formation of new associative memories, a form of declarative memory. These results provide some of the strongest direct evidence to date for learning-related plasticity in the hippocampus. The research findings are reported in the June 6 issue of the publication Science in a paper entitled “Single Neurons in the Monkey Hippocampus and the Learning of New Associations.” Since the 1950s, scientists have been aware of the link between the hippocampus and memory, but knew little of how this association manifested itself in neural activity. The NYU research team, led by NYU post-doctoral fellow Sylvia Wirth, NYU professor Wendy Suzuki and graduate student Marianna Yanike, examined the neural correlates of associative memory formation by using electrodes to monitor the electrical activity of individual neurons in the brains of monkeys performing an associative learning task. The neural and behavioral data was analyzed using dynamic estimation algorithms developed by post-doctoral fellows Loren Frank, Anne Smith and professor Emery Brown at Harvard University.

Researchers have identified the neural activity that occurs when the brain “sets the stage” for retaining a memory – a finding that could have important implications for memory research and help determine ways in which people can strengthen memories they want to retain while weakening ones they would rather forget. The results of the study appear as an advance online publication in the journal Nature Neuroscience. In two separate experiments with adults, UCI neuroscientist Michael Rugg, in collaboration with colleagues from University College London, looked at neural activity that preceded the presentation of single words. They found that measures of the activity could predict whether the words would be remembered in a later memory test. In the experiments, Rugg and his colleagues presented a group of young adults with a different word every four or five seconds, requiring them to make a judgment about a specific characteristic of the word, such as whether it referred to a living or a non-living thing. A moment before each word was presented, participants were “cued” with a visual signal that alerted them of the upcoming word. Neural activity caused by the cue was monitored through electroencephalograpy, or EEG, a method by which electrodes attached to the scalp measure underlying brain activity. Later, participants were shown the words again, along with words they had not previously been shown, and were asked to identify which ones had been presented in the first part of the experiment. © Copyright 2002-2006 UC Regents

By NICHOLAS WADE New recordings of electrical activity in the brain may explain a major part of its function, including how it consolidates daily memories, why it needs to dream and how it constructs models of the world to guide behavior. The recordings capture dialogue between the hippocampus, where initial memories of the day’s events are formed, and the neocortex, the sheet of neurons on the outer surface of the brain that mediates conscious thought and contains long-term memories. Such a dialogue had been thought to exist, but no one had been able to eavesdrop on it successfully. The new insight has emerged from recordings of rat brains but is likely to occur in much the same way in the human brain, which has analogous structures and the same basic principles of operation. The finding, reported on the Web site of the journal Nature Neuroscience by Daoyun Ji and Matthew A. Wilson, researchers at the Massachusetts Institute of Technology, showed that during nondreaming sleep, the neurons of both the hippocampus and the neocortex replayed memories — in repeated simultaneous bursts of electrical activity — of a task the rat learned the previous day. Copyright 2006 The New York Times Company

A better understanding of how memory works is emerging from a newfound ability to link a learning experience in a mouse to consequent changes in the inner workings of its neurons. Researchers, supported in part by the National Institutes of Health's National Institute of Mental Health (NIMH), have developed a way to pinpoint the specific cellular components that sustain a specific memory in genetically-engineered mice. "Remarkably, this research demonstrates a way to untangle precisely which cells and connections are activated by a particular memory," said NIMH Director Thomas Insel, M.D. "We are actually learning the molecular basis of learning and memory." For a memory to last long-term, the neural connections holding it need to be strengthened by incorporating new proteins triggered by the learning. Yet, it's been a mystery how these new proteins — born deep inside a neuron — end up becoming part of the specific connections in far-off neuronal extensions that encode that memory. By tracing the destinations of such migrating proteins, the researchers located the neural connections, called synapses, holding a specific fear memory. In the process, they discovered these synapses are distinguished by telltale molecular tags that enable them to capture the memory-sustaining proteins. Mark Mayford, Ph.D., and Naoki Matsuo, Ph.D., of the Scripps Research Institute, report on their findings in the February 22, 2008 issue of the journal Science.

Researchers from The University of Texas at Austin studying electric fish have gained new insight into how memory is stored at the level of neurons. Their finding, published in the Feb. 16 issue of Neuron, could help researchers better understand memory formation and neural disorders like epilepsy in humans. Dr. Harold Zakon, Dr. Jörg Oestreich and colleagues show that when electric fish zap each other in dark waters, their neurons store a memory of the sizzling communiqu� by turning on special cell membrane channels. The channels give the fish neurons the ability to retain a memory long after its original stimulus is gone. "There is short-term stimulation that results in long-term changes in excitability," says Zakon, professor of neurobiology. "Essentially, it is memory." The electric fish studied by Zakon and Oestreich discharge electrical signals to survey their environment and communicate with each other. "Every time they discharge, it's kind of like they are opening their eyes and closing them," says Zakon. "Each pulse of electricity is a snapshot of the environment. These guys are swimming around and discharging at a very regular frequency. They're digitizing their environment."

By Nayanah Siva By beaming a laser into the brains of fruit flies, scientists have created new memories from scratch. It's an "amazing piece of work," says neuroscientist Simon Schultz of Imperial College London. The memories are very simple: just the association that a particular stimulus is bad and should be avoided. As a first step to creating this association, neuroscientist Gero Miesenböck of the University of Oxford in the United Kingdom and colleagues studied fruit flies that preferred the odor of either 3-octanol (OCT) or 4-methylcyclohexanol (MCH). Next, the team electrically shocked the flies when one or the other odor was present. Naturally, the flies began to avoid the odor associated with the shock, even if they had preferred that odor in the first place. Miesenböck and colleagues then wanted to see whether they could program the flies to dislike an odor without shocking them first. To do this, they injected an engineered version of ATP--a source of cellular energy--into various neural circuits in the flies' brains. This time, when the flies encountered either OCT or MCH, the researchers flashed laser light into their brains. This released the engineered ATP, which activated neurons that release dopamine, a neurotransmitter believed to create aversive memories in flies. Sure enough, flies exposed to the laser light in the presence of OCT or MCH began to avoid that odor, just as though they had been shocked. © 2009 American Association for the Advancement of Science

HOUSTON-- A random perfume wafting through a garden breeze can suddenly trigger the vivid memory of a summer’s day six months earlier. A musical phrase can recollect an evening of dinner and dancing in the company of good friends. These apparently random remembrances, triggered by a sensory cue representing only a portion of the original memory, appear to be dependent on a particular region of the brain—the CA3 region of the hippocampus, say researchers from Baylor College of Medicine in Houston, collaborating with others from the Massachusetts Institute of Technology in Cambridge, and Hokkaido University School of Medicine in Sapporo Japan. Their findings appear in an article in the Journal Science, available currently (May 30, 2002) at the Science Express web site (www.sciencexpress.org). “It appears that the CA3 region of the hippocampus is essential for the phenomenon called ‘pattern completion’,” said Dr. Dan Johnston, professor of neuroscience at Baylor College of Medicine. “That is the ability to recall memories from partial representations of the original.”

A lot of people have come a lot of miles to attend this year’s SfN in San Diego. So perhaps I had travel in mind when I started off with a couple of posters loosely related to going places – admittedly on rather different scales� Firstly: getting around London by taxi. Eleanor Maguire and her student Katherine Woollett of University College London have been following up on Maguire’s previous – and rather well-publicised - study (Nature’s story at the time is here) on the brains of London cabbies. Back in 2000, they found that the size of a region called the hippocampus, which is involved in navigation and memory, is larger in London’s black cab drivers (who have to pass a foreboding test of the capital’s 25,000 streets, suitably titled The Knowledge) than in other people. Unfortunately for them, however, this expertise comes at a price to new learning and memory. A different part of the hippocampus actually decreases in size as a result of the enlargement of the rest of it. “It’s a story of loss and gain if you’re a taxi driver,” Maguire says. She wouldn’t be surprised, she told me, if this ‘give-and-take’ mechanism was being employed elsewhere in the brain too. Second travel titbit: getting humans to Mars. For completely different reasons, this form of transit might also impair your memory, as Bernard Rabin’s work on the effect of cosmic rays on rat’s brains suggests.

By NATALIE ANGIER The theory of relativity showed us that time and space are intertwined. To which our smarty-pants body might well reply: Tell me something I didn’t already know, Einstein. Researchers at the University of Aberdeen found that when people were asked to engage in a bit of mental time travel, and to recall past events or imagine future ones, participants’ bodies subliminally acted out the metaphors embedded in how we commonly conceptualized the flow of time. As they thought about years gone by, participants leaned slightly backward, while in fantasizing about the future, they listed to the fore. The deviations were not exactly Tower of Pisa leanings, amounting to some two or three millimeters’ shift one way or the other. Nevertheless, the directionality was clear and consistent. “When we talk about time, we often use spatial metaphors like ‘I’m looking forward to seeing you’ or ‘I’m reflecting back on the past,’ ” said Lynden K. Miles, who conducted the study with his colleagues Louise K. Nind and C. Neil Macrae. “It was pleasing to us that we could take an abstract concept such as time and show that it was manifested in body movements.” The new study, published in January in the journal Psychological Science, is part of the immensely popular field called embodied cognition, the idea that the brain is not the only part of us with a mind of its own. “How we process information is related not just to our brains but to our entire body,” said Nils B. Jostmann of the University of Amsterdam. “We use every system available to us to come to a conclusion and make sense of what’s going on.” Copyright 2010 The New York Times Company

By MATT RICHTEL SAN FRANCISCO — When one of the most important e-mail messages of his life landed in his in-box a few years ago, Kord Campbell overlooked it. Not just for a day or two, but 12 days. He finally saw it while sifting through old messages: a big company wanted to buy his Internet start-up. “I stood up from my desk and said, ‘Oh my God, oh my God, oh my God,’ ” Mr. Campbell said. “It’s kind of hard to miss an e-mail like that, but I did.” The message had slipped by him amid an electronic flood: two computer screens alive with e-mail, instant messages, online chats, a Web browser and the computer code he was writing. While he managed to salvage the $1.3 million deal after apologizing to his suitor, Mr. Campbell continues to struggle with the effects of the deluge of data. Even after he unplugs, he craves the stimulation he gets from his electronic gadgets. He forgets things like dinner plans, and he has trouble focusing on his family. His wife, Brenda, complains, “It seems like he can no longer be fully in the moment.” This is your brain on computers. Scientists say juggling e-mail, phone calls and other incoming information can change how people think and behave. They say our ability to focus is being undermined by bursts of information. Copyright 2010 The New York Times Company

Mushrooms aid total recall HELEN PEARSON Learning to love putrid pongs must take some nerve. But flies can learn smells even when critical nerve connections in their brains are blocked, researchers have found - although recalling the scents needs cells that are fully switched on1. The findings offer clues on how the mind keeps track of its memories. Flies like dung because of a brain nodule called the mushroom body. This knot of nerves is involved in learning and remembering smells - but whether it makes the memories, stores them or recalls them was unknown. 1.Keefe, A. D. & Szostak, J. W. Functional proteins from a random-sequence library. Nature 410, 715–718 (2001). © Macmillan Magazines Ltd 2001 - NATURE NEWS SERVICE Nature © Macmillan Publishers Ltd 2001 Reg. No. 785998 England.

An investigation of the activity of individual human nerve cells during the act of memory indicates that the brain’s nerve cells are even more specialized than many people think – no pun intended. Although nerve cells that change activity during the use of memory are widely distributed in the brain, individual neurons generally respond to specific aspects of memory. "For the first time, we’ve been able to show differences within regions of the temporal lobe in the way individual neurons respond to memory. Everything we’ve done to this point was to show that there are individual neurons that change activity --but we hadn’t been able to sort them out in any meaningful way. Now we can," says Dr. George Ojemann, professor of neurological surgery at the University of Washington. The findings appear in the January 2002 issue of Nature Neuroscience.

WINSTON-SALEM, N.C. – Symptoms of depression, irritability, and apathy are common among people with mild memory loss, known to doctors as "mild cognitive impairment," and often can be successfully treated, according to researchers who analyzed data from the massive Cardiovascular Health Study. The researchers from five medical centers including Wake Forest University Baptist Medical Center reported in the current Journal of the American Medical Association that their study, based on participants followed for more than 10 years, was the first to show that the appearance of psychiatric symptoms correlate with the development of mild cognitive impairment. While psychiatric symptoms occur in the majority of persons with outright dementia, "these are the first population-based estimates for neuropsychiatric symptoms in mild cognitive impairment," the group reported. "These symptoms have serious adverse consequences and should be inquired about and treated as necessary."

PITTSBURGH,– For estrogen to enhance learning and memory, nerve cells in the brain called cholinergic neurons are essential to the process, suggest animal studies performed by researchers from the University of Pittsburgh School of Pharmacy and reported in the November issue of Hormones and Behavior, the official journal of the Society for Behavioral Neuroendocrinology. "Estrogen replacement in postmenopausal women has important effects on mood and cognition. This research was focused on trying to understand what estrogen does in the brain to reduce the effects on brain aging and cognitive decline," stated Robert Gibbs, Pharm.D., associate professor of pharmaceutical sciences at the University of Pittsburgh School of Pharmacy. In the study, rats had their ovaries removed and some of the animals had specific cholinergic neurons destroyed. A few weeks after surgery, most of the animals were put on estrogen replacement therapy (ERT), while some were not.

Chapter 18. Learning and Memory: Neural Mechanisms