Manipulating memory with light: Scientists erase specific memories in mice

Manipulating memory with light: Scientists erase specific memories in mice

  8:13:00 PM    Science Lover

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Just look into the light: not quite, but researchers at the UC Davis Center for Neuroscience and Department of Psychology have used light to erase specific memories in mice, and proved a basic theory of how different parts of the brain work together to retrieve episodic memories.

During memory retrieval, cells in the hippocampus
connect to cells in the brain cortex.

Credit: Photo illustration by Kazumasa Tanaka and 
Brian Wiltgen/UC Davis

Optogenetics, pioneered by Karl Diesseroth at Stanford University, is a new technique for manipulating and studying nerve cells using light. The techniques of optogenetics are rapidly becoming the standard method for investigating brain function.

Kazumasa Tanaka, Brian Wiltgen and colleagues at UC Davis applied the technique to test a long-standing idea about memory retrieval. For about 40 years, Wiltgen said, neuroscientists have theorized that retrieving episodic memories -- memories about specific places and events -- involves coordinated activity between the cerebral cortex and the hippocampus, a small structure deep in the brain.

"The theory is that learning involves processing in the cortex, and the hippocampus reproduces this pattern of activity during retrieval, allowing you to re-experience the event," Wiltgen said. If the hippocampus is damaged, patients can lose decades of memories.

But this model has been difficult to test directly, until the arrival of optogenetics.

Wiltgen and Tanaka used mice genetically modified so that when nerve cells are activated, they both fluoresce green and express a protein that allows the cells to be switched off by light. They were therefore able both to follow exactly which nerve cells in the cortex and hippocampus were activated in learning and memory retrieval, and switch them off with light directed through a fiber-optic cable.

They trained the mice by placing them in a cage where they got a mild electric shock. Normally, mice placed in a new environment will nose around and explore. But when placed in a cage where they have previously received a shock, they freeze in place in a "fear response."

Tanaka and Wiltgen first showed that they could label the cells involved in learning and demonstrate that they were reactivated during memory recall. Then they were able to switch off the specific nerve cells in the hippocampus, and show that the mice lost their memories of the unpleasant event. They were also able to show that turning off other cells in the hippocampus did not affect retrieval of that memory, and to follow fibers from the hippocampus to specific cells in the cortex.

"The cortex can't do it alone, it needs input from the hippocampus," Wiltgen said. "This has been a fundamental assumption in our field for a long time and Kazu’s data provides the first direct evidence that it is true."

They could also see how the specific cells in the cortex were connected to the amygdala, a structure in the brain that is involved in emotion and in generating the freezing response.

Co-authors are Aleksandr Pevzner, Anahita B. Hamidi, Yuki Nakazawa and Jalina Graham, all at the Center for Neuroscience. The work was funded by grants from the Whitehall Foundation, McKnight Foundation, Nakajima Foundation and the National Science Foundation.

Story Source:
The above story is based on materials provided by University of California - Davis. Note: Materials may be edited for content and length.

Journal Reference:
Kazumasa Z. Tanaka, Aleksandr Pevzner, Anahita B. Hamidi, Yuki Nakazawa, Jalina Graham, Brian J. Wiltgen. Cortical Representations Are Reinstated by the Hippocampus during Memory Retrieval. Neuron, 2014 DOI: 10.1016/j.neuron.2014.09.037

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Imagination Can Change What We Hear and See

Imagination Can Change What We Hear and See

  1:24:00 PM    Science Lover

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A study from Karolinska Institut in Sweden shows, that our imagination may affect how we experience the world more than we perhaps think. What we imagine hearing or seeing "in our head" can change our actual perception. The study, which is published in the scientific journal Current Biology, sheds new light on a classic question in psychology and neuroscience -- about how our brains combine information from the different senses.

Illusion of colliding objects. (Credit: Image courtesy of Karolinska Institutet)

"We often think about the things we imagine and the things we perceive as being clearly dissociable," says Christopher Berger, doctoral student at the Department of Neuroscience and lead author of the study. "However, what this study shows is that our imagination of a sound or a shape changes how we perceive the world around us in the same way actually hearing that sound or seeing that shape does. Specifically, we found that what we imagine hearing can change what we actually see, and what we imagine seeing can change what we actually hear."

The study consists of a series of experiments that make use of illusions in which sensory information from one sense changes or distorts one's perception of another sense. Ninety-six healthy volunteers participated in total.

In the first experiment, participants experienced the illusion that two passing objects collided rather than passed by one-another when they imagined a sound at the moment the two objects met. In a second experiment, the participants' spatial perception of a sound was biased towards a location where they imagined seeing the brief appearance of a white circle. In the third experiment, the participants' perception of what a person was saying was changed by their imagination of a particular sound.

According to the scientists, the results of the current study may be useful in understanding the mechanisms by which the brain fails to distinguish between thought and reality in certain psychiatric disorders such as schizophrenia. Another area of use could be research on brain computer interfaces, where paralyzed individuals' imagination is used to control virtual and artificial devices.

"This is the first set of experiments to definitively establish that the sensory signals generated by one's imagination are strong enough to change one's real-world perception of a different sensory modality" says Professor Henrik Ehrsson, the principle investigator behind the study.

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Gene Variants Linked to Educational Attainment

Gene Variants Linked to Educational Attainment

  7:49:00 AM    Science Lover

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A multi-national team of researchers has identified genetic markers that predict educational attainment by pooling data from more than 125,000 individuals in the United States, Australia, and 13 western European countries.

A multi-national team of researchers has identified genetic markers that predict educational attainment by pooling data from more than 125,000 individuals in the United States, Australia, and 13 western European countries. (Credit: © Tom Wang / Fotolia)

The study, which appears in the journal Science, was conducted by the Social Science Genetic Association Consortium (SSGAC), which includes researchers at NYU, Erasmus University, Cornell University, Harvard University, the University of Bristol, and the University of Queensland, among other institutions.

The SSGAC conducted what is called a genome-wide association study (GWAS) to explore the link between genetic variation and educational attainment -- the number of years of schooling completed by an individual and whether he or she graduated college. In a GWAS, researchers test hundreds of thousands of genetic markers for association with some characteristics such as a disease, trait or life outcome.

Because the sample included people from different countries -- where markers for schooling vary significantly -- the research team adopted the International Standard Classification of Education (ISCED) scale, which is a commonly used method for establishing a uniform measure of educational attainment across cohorts.

Anticipating that very large samples would be required to credibly detect genetic associations, the SSGAC researchers assembled a total sample size more than 10 times larger than any previous genetic study of any social-scientific outcome. The team examined associations between educational attainment and genetic variants called single-nucleotide polymorphisms, or SNPs, which are tiny changes at a single location in a person's genetic code.

The study found that the genetic markers with the strongest effects on educational attainment could each only explain two one-hundredths of a percentage point (0.02 percent). To put that figure into perspective, it is known from earlier research that the SNP with the largest effect on human height accounts for about 0.40 percent of the variation.

Combining the two million examined SNPs, the SSGAC researchers were able to explain about 2 percent of the variation in educational attainment across individuals, and anticipate that this figure will rise as larger samples become available.

"We hope that our findings will eventually be useful for understanding biological processes underlying learning, memory, reading disabilities and cognitive decline in the elderly," said co-author Daniel Benjamin, a behavioral economist at Cornell who is a co-director of the SSGAC.

"Another contribution of our study is that it will strengthen the methodological foundations of social-science genetics," said David Cesarini, an NYU assistant professor at the Center for Experimental Social Science and the Center for Neuroeconomics, who also co-directs the SSGAC. "We used 125,000 individuals to conduct this study. Previous studies used far smaller samples, sometimes as small as 100 individuals and rarely more than 10,000. These small samples make sense under the assumption that individual genes have large effects. However, if genes have small effects, as our study shows, then sample sizes need to be very large to produce robust findings that will reliably replicate in other samples."

The researchers were careful to note that they have not discovered "the gene for education" or that these findings somehow imply that a person's educational attainment is determined at birth.

"For most outcomes that we study as social scientists, genetic influences are likely to operate through environmental channels that are modifiable," explained NYU sociologist Dalton Conley, one of the study's co-authors who also serves on the Advisory Board of the SSGAC. "We have now taken a small but important first step toward identifying the specific genetic variants that predict educational attainment. Armed with this knowledge, we can now begin to examine how other factors -- including public policy, parental roles, and economic status -- dampen or amplify genetic effects and ultimately devise better remedies to bolster educational outcomes." 

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IQ Predicted by Ability to Filter Visual Motion

IQ Predicted by Ability to Filter Visual Motion

  8:36:00 PM    Science Lover

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A brief visual task can predict IQ, according to a new study. This surprisingly simple exercise measures the brain's unconscious ability to filter out visual movement. The study shows that individuals whose brains are better at automatically suppressing background motion perform better on standard measures of intelligence. The test is the first purely sensory assessment to be strongly correlated with IQ and may provide a non-verbal and culturally unbiased tool for scientists seeking to understand neural processes associated with general intelligence.

Intelligence is closely linked to a person's ability to filter out background movement, according to a new cognitive science study from the University of Rochester. (Credit: J. Adam Fenster, University of Rochester)

"Because intelligence is such a broad construct, you can't really track it back to one part of the brain," says Duje Tadin, a senior author on the study and an assistant professor of brain and cognitive sciences at the University of Rochester. "But since this task is so simple and so closely linked to IQ, it may give us clues about what makes a brain more efficient, and, consequently, more intelligent."

The unexpected link between IQ and motion filtering was reported online in the Cell Press journal Current Biology on May 23 by a research team lead by Tadin and Michael Melnick, a doctoral candidate in brain and cognitive sciences at the University of Rochester.

In the study, individuals watched brief video clips of black and white bars moving across a computer screen. Their sole task was to identify which direction the bars drifted: to the right or to the left. The bars were presented in three sizes, with the smallest version restricted to the central circle where human motion perception is known to be optimal, an area roughly the width of the thumb when the hand is extended. Participants also took a standardized intelligence test.

As expected, people with higher IQ scores were faster at catching the movement of the bars when observing the smallest image. The results support prior research showing that individuals with higher IQs make simple perceptual judgments swifter and have faster reflexes. "Being 'quick witted' and 'quick on the draw' generally go hand in hand," says Melnick.

But the tables turned when presented with the larger images. The higher a person's IQ, the slower they were at detecting movement. "From previous research, we expected that all participants would be worse at detecting the movement of large images, but high IQ individuals were much, much worse," says Melnick. That counter-intuitive inability to perceive large moving images is a perceptual marker for the brain's ability to suppress background motion, the authors explain. In most scenarios, background movement is less important than small moving objects in the foreground. Think about driving in a car, walking down a hall, or even just moving your eyes across the room. The background is constantly in motion.

The key discovery in this study is how closely this natural filtering ability is linked to IQ. The first experiment found a 64 percent correlation between motion suppression and IQ scores, a much stronger relationship than other sensory measures to date. For example, research on the relationship between intelligence and color discrimination, sensitivity to pitch, and reaction times have found only a 20 to 40 percent correlation. "In our first experiment, the effect for motion was so strong," recalls Tadin, "that I really thought this was a fluke."

So the group tried to disprove the findings from the initial 12-participant study conducted while Tadin was at Vanderbilt University working with co-author Sohee Park, a professor of psychology. They reran the experiment at the University of Rochester on a new cohort of 53 subjects, administering the full IQ test instead of an abbreviated version and the results were even stronger; correlation rose to 71 percent. The authors also tested for other possible explanations for their findings.

For example, did the surprising link to IQ simply reflect a person's willful decision to focus on small moving images? To rule out the effect of attention, the second round of experiments randomly ordered the different image sizes and tested other types of large images that have been shown not to elicit suppression. High IQ individuals continued to be quicker on all tasks, except the ones that isolated motion suppression. The authors concluded that high IQ is associated with automatic filtering of background motion.

"We know from prior research which parts of the brain are involved in visual suppression of background motion. This new link to intelligence provides a good target for looking at what is different about the neural processing, what's different about the neurochemistry, what's different about the neurotransmitters of people with different IQs," says Tadin.

The relationship between IQ and motion suppression points to the fundamental cognitive processes that underlie intelligence, the authors write. The brain is bombarded by an overwhelming amount of sensory information, and its efficiency is built not only on how quickly our neural networks process these signals, but also on how good they are at suppressing less meaningful information. "Rapid processing is of little utility unless it is restricted to the most relevant information," the authors conclude.

The researchers point out that this vision test could remove some of the limitations associated with standard IQ tests, which have been criticized for cultural bias. "Because the test is simple and non-verbal, it will also help researchers better understand neural processing in individuals with intellectual and developmental disabilities," says co-author Loisa Bennetto, an associate professor of psychology at the University of Rochester.

Bryan Harrison, a doctoral candidate in clinical and social psychology at the University of Rochester is also an author on the paper. The research was supported by grants from the National Institutes of Health.

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Bad Decisions Arise from Faulty Information, Not Faulty Brain Circuits

Bad Decisions Arise from Faulty Information, Not Faulty Brain Circuits

  2:00:00 PM    Science Lover

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Making decisions involves a gradual accumulation of facts that support one choice or another. A person choosing a college might weigh factors such as course selection, institutional reputation and the quality of future job prospects.

Researchers have found that it might be the information rather than the brain's decision-making process that is to blame. The researchers report that erroneous decisions tend to arise from errors, or "noise," in the information coming into the brain rather than errors in how the brain accumulates information.

But if the wrong choice is made, Princeton University researchers have found that it might be the information rather than the brain's decision-making process that is to blame. The researchers report in the journal Science that erroneous decisions tend to arise from errors, or "noise," in the information coming into the brain rather than errors in how the brain accumulates information.

These findings address a fundamental question among neuroscientists about whether bad decisions result from noise in the external information -- or sensory input -- or because the brain made mistakes when tallying that information. In the example of choosing a college, the question might be whether a person made a poor choice because of misleading or confusing course descriptions, or because the brain failed to remember which college had the best ratings.

Previous measurements of brain neurons have indicated that brain functions are inherently noisy. The Princeton research, however, separated sensory inputs from the internal mental process to show that the former can be noisy while the latter is remarkably reliable, said senior investigator Carlos Brody, a Princeton associate professor of molecular biology and the Princeton Neuroscience Institute (PNI), and a Howard Hughes Medical Institute Investigator.

"To our great surprise, the internal mental process was perfectly noiseless. All of the imperfections came from noise in the sensory processes," Brody said. Brody worked with first author Bingni Brunton, now a postdoctoral research associate in the departments of biology and applied mathematics at the University of Washington; and Matthew Botvinick, a Princeton associate professor of psychology and PNI.

The research subjects -- four college-age volunteers and 19 laboratory rats -- listened to streams of randomly timed clicks coming into both the left ear and the right ear. After listening to a stream, the subjects had to choose the side from which more clicks originated. The rats had been trained to turn their noses in the direction from which more clicks originated.

The test subjects mostly chose the correct side but occasionally made errors. By comparing various patterns of clicks with the volunteers' responses, researchers found that all of the errors arose when two clicks overlapped, and not from any observable noise in the brain system that tallied the clicks. This was true in experiment after experiment utilizing different click patterns, in humans and rats.

The researchers used the timing of the clicks and the decision-making behavior of the test subjects to create computer models that can be used to indicate what happens in the brain during decision-making. The models provide a clear window into the brain during the "mulling over" period of decision-making, the time when a person is accumulating information but has yet to choose, Brody said.

"Before we conducted this study, we did not have a way of looking at this process without inserting electrodes into the brain," Brody said. "Now thanks to our model, we have an estimation of what is going on at each moment in time during the formation of the decision."

The study suggests that information represented and processed in the brain's neurons must be robust to noise, Brody said. "In other words, the 'neural code' may have a mechanism for inherent error correction," he said.

"The new work from the Brody lab is important for a few reasons," said Anne Churchland, an assistant professor of biological sciences at Cold Spring Harbor Laboratory who studies decision-making and was not involved in the study. "First, the work was very innovative because the researchers were able to study carefully controlled decision-making behavior in rodents. This is surprising in that one might have guessed rodents were incapable of producing stable, reliable decisions that are based on complex sensory stimuli.

"This work exposed some unexpected features of why animals, including humans, sometimes make incorrect decisions," Churchland said. "Specifically, the researchers found that errors are mostly driven by the inability to accurately encode sensory information. Alternative possibilities, which the authors ruled out, included noise associated with holding the stimulus in mind, or memory noise, and noise associated with a bias toward one alternative or the other."

The work was funded by the Howard Hughes Medical Institute, Princeton University and National Institutes of Health training grants.

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Brain Imaging Study Finds Evidence of Basis for Caregiving Impulse

Brain Imaging Study Finds Evidence of Basis for Caregiving Impulse

  7:17:00 PM    Science Lover

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Distinct patterns of activity -- which may indicate a predisposition to care for infants-- appear in the brains of adults who view an image of an infant face -- even when the child is not theirs, according to a study by researchers at the National Institutes of Health and in Germany, Italy, and Japan.

Researchers have found that distinct patterns of activity --
which may indicate a predisposition to care for infants --
appear in the brains of adults who view an image of an
infant face -- even when the child is not theirs.
(Credit: © Jamey Ekins / Fotolia)

Seeing images of infant faces appeared to activate in the adult's brains circuits that reflect preparation for movement and speech as well as feelings of reward.

The findings raise the possibility that studying this activity will yield insights into care giving behavior, but also in cases of child neglect or abuse.

"These adults have no children of their own. Yet images of a baby's face triggered what we think might be a deeply embedded response to reach out and care for that child," said senior author Marc H. Bornstein, Ph.D., head of the Child and Family Research Section of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the NIH institute that collaborated on the study.

While the researchers recorded participants' brain activity, the participants did not speak or move. Yet their brain activity was typical of patterns preceding such actions as picking up or talking to an infant, the researchers explained. The activity pattern could represent a biological impulse that governs adults' interactions with small children.

From their study results, the researchers concluded that this pattern is specific to seeing human infants. The pattern did not appear when the participants looked at photos of adults or of animals -- even baby animals.

Along with Dr. Bornstein, the research was carried out by first author Andrea Caria, Ph.D., of the University of Tuebingen, in Germany; Paola Venuti of the Department of Cognitive Science of University of Trento in Italy; Gianluca Esposito of the RIKEN Brain Science Institute in Saitama, Japan; researchers from the Max Planck Institute for Biological Cybernetics and Eberhard Karls University, in Tuebingen, Germany.

Their findings appear in the journal NeuroImage.

To collect the data, the researchers showed seven men and nine women a series of images while recording their brain activity with a functional magnetic resonance imaging scanner. In the scanner, participants viewed images of puppy and kitten faces, full-grown dogs and cats, human infants and adults.

When the researchers compared the areas and strength of brain activity in response to each kind of image, they found that infant images evoked more activity than any of the other images in brain areas associated with three main functions:

• Premotor and preverbal activity -- The researchers documented increased activity in the premotor cortex and the supplemental motor area, which are regions of the brain directly under the crown of the head. These regions orchestrate brain impulses preceding speech and movement but before movement takes place.
• Facial recognition -- Activity in the fusiform gyrus -- on each side of the brain, about where the ears are -- is associated with processing of information about faces. Activity the researchers detected in the fusiform gyrus may indicate heightened attention to the movement and expressions on an infant's face, the researchers said.
• Emotion and reward -- Activity deep in the brain areas known as the insula and the cingulate cortex indicated emotional arousal, empathy, attachment and feelings linked to motivation and reward, the researchers said. Other studies have documented a similar pattern of activity in the brains of parents responding to their own infants.

Participants also rated how they felt when viewing adult and infant faces. They reported feeling more willing to approach, smile at, and communicate with an infant than an adult. They also recorded feeling happier when viewing images of infants.

Taken together, the researchers contend, the findings suggest a readiness to interact with infants that previously has been only inferred, and only from parents. Such brain activity in nonparents could indicate that the biological makeup of humans includes a mechanism to ensure that infants survive and receive the care they need to grow and develop.

However, signs of readiness to care for a child that appear in the brains of some or even most adults do not necessarily mean the same patterns will appear in the brains of all adults, Dr. Bornstein said. "It's equally important to investigate what's happening in the brains of those who have neglected or abused children," he said. "Additional studies could help us confirm and understand what appears to be a parenting instinct in adults, both when the instinct functions and when it fails to function."

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Brain Co-Opts the Body to Promote Moral Behavior, Study Finds

Brain Co-Opts the Body to Promote Moral Behavior, Study Finds

  8:19:00 PM    Science Lover

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The human brain may simulate physical sensations to prompt introspection, capitalizing on moments of high emotion to promote moral behavior, according to a USC researcher.

Girl being reflective. Researchers found that individuals who were told stories designed to evoke compassion and admiration for virtue sometimes reported that they felt a physical sensation in response. (Credit: © Paul Hill / Fotolia)

Mary Helen Immordino-Yang of the USC Brain and Creativity Institute and the USC Rossier School of Education found that individuals who were told stories designed to evoke compassion and admiration for virtue sometimes reported that they felt a physical sensation in response. These psycho-physical "pangs" of emotion are very real -- they're detectable with brain scans -- and may be evidence that pro-social behavior is part of human survival.

Immordino-Yang's hypothesis, borne out thus far by her research, is that the feeling or emotional reactions in the body may sometimes prompt introspection, and can ultimately promote moral choices and motivation to help or emulate others.

"These emotions are foundational for morality and social learning. They have the power to change the course of your very life," Immordino-Yang said.

Her article appears in the July issue of Emotion Review.

In one instance cited in the article, a participant responded to a story of a little boy's selflessness toward his mother by reporting that he felt like there was a "balloon or something under my sternum, inflating and moving up and out." While pondering this physical sensation, the participant paused for a moment and considered his own relationship with his parents. Ultimately, he voiced a promise to express more gratitude toward them.



Researchers noted similar reactions to varying degrees in the test's other participants. Immordino-Yang's team has performed about 50 of these qualitative analyses in Beijing and at USC. The researchers provide the emotional story, then record the participant's reaction, and also use brain scans to record the physiological response.

"It's a systematic but naturalistic way to induce these emotions." Immordino-Yang said. After being told an emotional true story during a private, taped interview, the participant is simply asked to describe how he or she feels.

Immordino-Yang said she isn't surprised at the findings, though she is excited by them.

"We are an intensely social species," she said. "Our very biology is a social one. For centuries poets have described so-called gut feelings during social emotions. Now we are uncovering the biological evidence."

Future analysis of the data her team has gathered will focus on discovering to what degree culture and individual styles and experiences influence these reactions, as well as how they develop in children and how they can be promoted by education.

This research was supported by the Brain and Creativity Institute, the USC Provost's grant for Advancing Scholarship in the Humanities and Social Sciences, and the Rossier School of Education.

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Brain Matter Linked to Introspective Thoughts Structure of Prefrontal Cortex Helps Humans Think About One's Own Thinking

Brain Matter Linked to Introspective Thoughts Structure of Prefrontal Cortex Helps Humans Think About One's Own Thinking

  9:51:00 AM    Science Lover

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A specific region of the brain appears to be larger in individuals who are good at turning their thoughts inward and reflecting upon their decisions, according to new research published in the journal Science. This act of introspection -- or "thinking about your thinking" -- is a key aspect of human consciousness, though scientists have noted plenty of variation in peoples' abilities to introspect.

Views of inflated cortical surface showing areas of brain gray matter correlating with introspective accuracy. (Credit: Image © Science/AAAS)

The new study will be published in the 17 September issue of the journal Science. Science is published by AAAS, the nonprofit science society.

In light of their findings, this team of researchers, led by Prof. Geraint Rees from University College London, suggests that the volume of gray matter in the anterior prefrontal cortex of the brain, which lies right behind our eyes, is a strong indicator of a person's introspective ability. Furthermore, they say the structure of white matter connected to this area is also linked to this process of introspection.

It remains unclear, however, how this relationship between introspection and the two different types of brain matter really works. These findings do not necessarily mean that individuals with greater volume of gray matter in that region of the brain have experienced -- or will experience -- more introspective thoughts than other people. But, they do establish a correlation between the structure of gray and white matter in the prefrontal cortex and the various levels of introspection that individuals may experience.

In the future, the discovery may help scientists understand how certain brain injuries affect an individual's ability to reflect upon their own thoughts and actions. With such an understanding, it may eventually be possible to tailor appropriate treatments to patients, such as stroke victims or those with serious brain trauma, who may not even understand their own conditions.

"Take the example of two patients with mental illness -- one who is aware of their illness and one who is not," said one of the study's authors, Stephen Fleming from University College London. "The first person is likely to take their medication, but the second is less likely. If we understand self-awareness at the neurological level, then perhaps we can also adapt treatments and develop training strategies for these patients."

This new study was born from collaboration between Rees' group, which investigates consciousness, and another group at University College London led by Prof. Ray Dolan, which studies decision-making. Fleming, together with co-author Rimona Weil, designed an experiment to measure both an individual's performance at a task, as well as how confident that individual felt about his or her decisions during the task. By taking note of how accurately the study's participants were able to judge their own decision-making, the researchers were able to gain insight into the participants' introspective abilities.

To begin, Fleming and Weil recruited 32 healthy human participants and showed them two screens, each containing six patterned patches. One of the screens, however, contained a single patch that was brighter than all the rest. The researchers asked the participants to identify which screen contained the brighter patch, and then to rate how confident they felt about their final answer. After the experiment, participants' brains were scanned using magnetic resonance imaging, or MRI.

Fleming and the researchers designed the task to be difficult, so that participants were never completely sure if their answer was correct. They reasoned that participants who are good at introspection would be confident after making correct decisions about the patch, and less confident when they were incorrect about the patch. By adjusting the task, the researchers ensured all of the participants' decision-making abilities were on par with each others' -- only the participants' knowledge of their own decision-making abilities differed.

"It's like that show, 'Who Wants to Be a Millionaire?'" said Weil. "An introspective contestant will go with his or her final answer when they are quite sure of it, and perhaps phone a friend when they are unsure. But, a contestant who is less introspective would not be as effective at judging how likely their answer is to be correct."

So, although each participant performed equally well at the task, their introspective abilities did vary considerably, the researchers confirmed. By comparing the MRI scans of each participant's brain, they could then identify a correlation between introspective ability and the structure of a small area of the prefrontal cortex. An individual's meta-cognitive, or "higher-thinking," abilities were significantly correlated with the amount of gray matter in the right anterior prefrontal cortex and the structure of neighboring white matter, Rees and his team found.

These findings, however, could reflect the innate differences in our anatomy, or alternatively, the physical effects of experience and learning on the brain. The latter possibility raises the exciting prospect that there may be a way to "train" meta-cognitive abilities by exploiting the malleable nature of these regions of prefrontal cortex. But, more research is needed to explore the mental computations behind introspection -- and then to link these computations to actual biological processes.

"We want to know why we are aware of some mental processes while others proceed in the absence of consciousness," said Fleming. "There may be different levels of consciousness, ranging from simply having an experience, to reflecting upon that experience. Introspection is on the higher end of this spectrum -- by measuring this process and relating it to the brain we hope to gain insight into the biology of conscious thought."

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Remembering to Forget: The Amnesic Effect of Daydreaming

Remembering to Forget: The Amnesic Effect of Daydreaming

  11:25:00 AM    Science Lover

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When your mind drifts, it's hard to remember what was going on before you stopped paying attention. Now a new study has found that the effect is stronger when your mind drifts farther -- to memories of an overseas vacation instead of a domestic trip, for example, or a memory in the more distant past.

When your mind drifts, it's hard to remember what was going on before you stopped paying attention. Now a new study has found that the effect is stronger when your mind drifts farther -- to memories of an overseas vacation instead of a domestic trip, for example, or a memory in the more distant past. (Credit: iStockphoto)

Psychologists have known for a while that context is important to remembering. If you leave the place where a memory was made -- its context -- it will be harder for you to recall the memory. Previous studies had also found that thinking about something else -- daydreaming or mind-wandering -- blocks access to memories of the recent past. Psychological scientists Peter F. Delaney and Lili Sahakyan of the University of North Carolina at Greensboro and Colleen M. Kelley and Carissa A. Zimmerman of Florida State University wanted to know if the content of your daydreams affects your ability to access a recently-acquired memory.

For one experiment, each participant looked at a list of words as they appeared on a computer screen, one at a time. Then they were told to think either about home -- where they'd been that morning -- or about their parents' house -- where they hadn't been in several weeks. Next, the participant was shown a second list of words. At the end of the test, they had to recall as many of the words from the two lists as possible. Participants who had thought about the place they'd been only a few hours before remembered more of the words from the first list than did participants who had thought back several weeks. The same was true for memories about place, tested in a second experiment. Those who thought about a vacation within the U.S. remembered more words than those who thought about a vacation abroad. The study is published in Psychological Science, a journal of the Association for Psychological Science.

One practical application of the research might be for people who want to forget about something. "If there's something you don't feel like thinking about, you're better off remembering a more distant event than a close event, to try to put it out of your mind for a while," says Delaney. "It can help you feel like you're in a different situation."

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Great Apes 'Play' Tag to Keep Competitive Advantage

Great Apes 'Play' Tag to Keep Competitive Advantage

  9:29:00 AM    Science Lover

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Gorillas hit-and-run in 'games' of tag in the same way humans do and for the same reason -- to keep their competitive advantage, a new study has found.

Gorilla composite image showing a tag sequence. 
(Credit: Image courtesy of University of Portsmouth)

It is the first study to show apes, like humans, will hit a playmate then run in order to try to get away with the upper hand.

The research was carried out by behavioural biologist Dr Marina Davila Ross of the University of Portsmouth and colleagues lead author Edwin van Leeuwen from the Free University of Amsterdam and Dr Elke Zimmerman from the University of Veterinary Medicine in Germany. The paper is published in the Royal Society journal Biology Letters.

The research is the first to consider if animals respond to unfair situations in a natural social setting. Previous studies have all been carried out in laboratories.

Dr Davila Ross said: "This study shows a new opportunistic side to apes.

"Our findings on gorilla play show important similarities with the children's game of tag. Not only did the gorillas in our study hit their playmates and then run away chased by their playmates, but they also switched their roles when hit so the chaser became the chased and vice versa.

"Experimental research has already demonstrated that animals with the disadvantage in an unfair situation show an aversion to the unfairness so with that knowledge and our own study we can conclude that humans are not unique in their ability to change their behaviour in social situations depending on whether they have the advantage or disadvantage in an unfair situation.

Scientists cannot categorically state that gorillas play tag but those observed show the same behaviour as humans.

Dr Davila Ross said such unfair play behaviours are likely to be valuable because they allow apes -- and humans -- to test the limits of what is acceptable behaviour and to test their peers and even their parents.

She said: "This study is the first to empirically show that apes use play to explore the ramifications of unfair social situations."

The study also revealed that a hard hit resulted in a bigger reaction than a gentle hit, which was likely to be ignored.

The researchers studied the behaviour of great apes at play because their behaviour is less likely to be affected by the strengths and ranks of the competitors as they would be in a serious context, such as interactions related to food.

Dr Davila Ross said it was likely that the lessons learned in play fighting helped apes deal with real conflict, and that by 'role-playing' the chaser and the chased the apes would develop more refined and sophisticated communication skills. The study indicated that these chase roles of the gorillas were distinct with the ones doing the chasing predominantly showing a play face and hitting the other ones once they reach them.

Dr Davila Ross is an expert in primate behaviour with special interest in play and laughter and a research fellow in Portsmouth's psychology department. She and colleagues studied videos of 21 gorillas from six colonies play fighting in five European zoos. The videos on these specific chase behaviours were filmed and collected by Dr Davila Ross over a period of three years.

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Robot Teaches How Humans Develop Trust

Robot Teaches How Humans Develop Trust

  10:49:00 PM    Science Lover

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What can a wide-eyed, talking robot teach us about trust?

A lot, according to Northeastern psychology professor David DeSteno, and his colleagues, who are conducting innovative research to determine how humans decide to trust strangers -- and if those decisions are accurate.

The interdisciplinary research project, funded by the National Science Foundation (NSF), is being conducted in collaboration with Cynthia Breazeal, director of the MIT Media Lab's Personal Robots Group, Robert Frank, an economist, and David Pizarro, a psychologist, both from Cornell.

David DeSteno and MIT's Jin Joo Lee worked with 
Nexi the robot on the research project. 
(Credit: Photo by Mary Knox Merrill.)

The researchers are examining whether nonverbal cues and gestures could affect our trustworthiness judgments. "People tend to mimic each other's body language," said DeSteno, "which might help them develop intuitions about what other people are feeling -- intuitions about whether they'll treat them fairly."

This project tests their theories by having humans interact with the social robot, Nexi, in an attempt to judge her trustworthiness. Unbeknownst to participants, Nexi has been programmed to make gestures while speaking with selected participants -- gestures that the team hypothesizes could determine whether or not she's deemed trustworthy.

"Using a humanoid robot whose every expression and gesture we can control will allow us to better identify the exact cues and psychological processes that underlie humans' ability to accurately predict if a stranger is trustworthy," said DeSteno.

During the first part of the experiment, Nexi makes small talk with her human counterpart for 10 minutes, asking and answering questions about topics such as traveling, where they are from and what they like most about living in Boston.

"The goal was to simulate a normal conversation with accompanying movements to see what the mind would intuitively glean about the trustworthiness of another," said DeSteno.

The participants then play an economic game called "Give Some," which asks them to determine how much money Nexi might give them at the expense of her individual profit. Simultaneously, they decide how much, if any, they'll give to Nexi. The rules of the game allow for two distinct outcomes: higher individual profit for one and loss for the other, or relatively smaller and equal profits for both partners.

"Trust might not be determined by one isolated gesture, but rather a 'dance' that happens between the strangers, which leads them to trust or not trust the other," said DeSteno, who, with his colleagues, will continue testing their theories by seeing if Nexi can be taught to predict the trustworthiness of human partners.

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Neuroscientists Can Predict Your Behavior

Neuroscientists Can Predict Your Behavior

  10:22:00 AM    Science Lover

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In a study with implications for the advertising industry and public health organizations, UCLA neuroscientists have shown they can use brain scanning to predict whether people will use sunscreen during a one-week period even better than the people themselves can.

Precuneus and medial prefrontal cortex highlighted 
in brain. In this study, activity in the medial prefrontal 
region helped researchers predict which study participants 
would increase their sunscreen use, even better than 
the participants themselves could predict. 
(Credit: Image courtesy of UCLA)

"There is a very long history within psychology of people not being very good judges of what they will actually do in a future situation," said the study's senior author, Matthew Lieberman, a UCLA professor of psychology and of psychiatry and biobehavioral sciences. "Many people 'decide' to do things but then don't do them."

The new study by Lieberman and lead author Emily Falk, who earned her doctorate in psychology from UCLA this month, shows that increased activity in a brain region called the medial prefrontal cortex among individuals viewing and listening to public service announcement slides on the importance of using sunscreen strongly indicated that these people were more likely to increase their use of sunscreen the following week, even beyond the people's own expectations.

"From this region of the brain, we can predict for about three-quarters of the people whether they will increase their use of sunscreen beyond what they say they will do," Lieberman said. "If you just go by what people say they will do, you get fewer than half of the people accurately predicted, and using this brain region, we could do significantly better."

"While most people's self-reports are not very accurate, they do not realize their self-reports are wrong so often in predicting future behavior," Falk said. "It is surprising to find out that some technique might be able to predict my own behavior better than I can. Yet the brain seems to reveal something important that we may not even realize."

The study, the first persuasion study in neuroscience to predict behavior change, appears June 23 in the Journal of Neuroscience.

For the study, Falk, Lieberman and their collaborators sought people who did not use sunscreen every day. The study group consisted of 20 participants, mostly UCLA students, 10 female and 10 male. The participants had their brains scanned using functional magnetic resonance imaging (fMRI) at UCLA's Ahmanson-Lovelace Brain Mapping Center as they saw and heard a series of public service announcements. They were also asked about their intentions to use sunscreen over the next week and their attitudes about sunscreen.

The participants were then contacted a week later and asked on how many days during the week they had used sunscreen.

Lieberman and Falk focused on part of the brain's medial prefrontal cortex, which is located in the front of the brain, between the eyebrows. This brain region is associated with self-reflection -- thinking about what we like and do not like and our motivations and desires.

"It is the one region of the prefrontal cortex that we know is disproportionately larger in humans than in other primates," Lieberman said. "This region is associated with self-awareness and seems to be critical for thinking about yourself and thinking about your preferences and values."

The researchers developed a model based on 10 people and tested it on the next 10. They shuffled the 20 people in different ways to test the model. There are more than 180,000 ways to divide the 20 people into groups, Falk said.

"We ran a simulation of the 180,000 combinations, developed our model on the first 10 subjects on each of the 180,000 simulations, and tested it on the second 10," Falk said. "We saw a very reliable relationship, where for the vast majority of the 180,000 ways to divide the group up, this one region of the brain, the medial prefrontal cortex, does a very good job of predicting sunscreen use in the second group."

This finding could be relevant to many public health organizations, as well as the advertising industry, Lieberman and Falk said.

"For advertisers, there may be a lot more that is knowable than is known, and this is a data-driven method for knowing more about how to create persuasive messages," said Lieberman, one of the founders of social cognitive neuroscience.

Neural focus groups

While 19th-century department store pioneer John Wanamaker (quoted at the beginning of this release) advertised effectively for his stores in newspapers, he still said he was wasting half his advertising budget -- only he didn't know which half.

"We're learning something about which half," Lieberman said.

While advertising agencies often use focus groups to test commercials and movie trailers, in the future they and public health officials perhaps should add "neural focus groups" to test which messages will be effective while monitoring the brain activity of their subjects.

"A problem with standard focus groups," Falk said, "is that people are lousy at reporting what they will actually do. We have not had much to supplement that approach, but in the future it may be possible to create what we are calling 'neural focus groups.' Instead of talking with people about what they think they will do, a public health or advertising agency can study their brains and learn what they are really likely to do and how an advertisement would be likely to affect millions of other people as well."

"Given that there are emerging technologies that are relatively portable and approximate some of what fMRI can do at a fraction of the cost, looking to the brain to shape persuasive messages could become a reality," Lieberman said. "But we're just at the beginning. This is one of the first papers on anything like this. There will be a series of papers over the next 10 years or more that will tell us what factors are driving neural responses."

"We hope to build a sophisticated model of persuasion that may incorporate multiple brain regions," said Falk, who studies the neural basis of persuasion and attitude change. She has been hired by the University of Michigan-Ann Arbor as an assistant professor of communication studies and psychology and a member of the university's Institute for Social Research, starting in September.

While some people have emphasized reasoning and emotion as key areas on which to base advertising campaigns, a key question may be whether messages and advertisements can be produced that "make people feel, 'This is about me and is relevant to my preferences and motivations,'" Falk said. "Perhaps effective messages reinforce our values, our self-identity, what motivates us. We will learn much more as we continue this line of research over the years."

Neuroscientists will learn whether they can predict behavior better and are likely to obtain a more nuanced understanding of the roles played by different parts of brain regions, said Falk, who this March received UCLA's Charles E. and Sue K. Young Award for outstanding research and teaching. She is interested in how to make more effective health and other public service messages aimed at young adults.

"There is still much we do not know about how to get people to make healthier choices," Falk said. "We hope to learn much more about what makes messages more or less persuasive."

Different brain regions may be important for persuading people to tell or e-mail their friends about a health message, product or service; Lieberman and Falk are studying this issue of "creating buzz" as well.

However, the implications of the research go far beyond advertising, Lieberman said.

"There are many applications beyond how you make a good 30-second commercial," he said, "including how teachers can communicate better so their students won't tune out or how doctors can convince patients to stick to their instructions. We all use persuasion in some form or another every day."

Beware of hucksters

Some people are already offering "neuro-marketing," purporting to help businesses sell their products and help candidates run their advertising campaigns, Lieberman noted. They may, for example, recommend what colors and sounds to use in commercials. Is this effective, or are they claiming expertise they do not possess?

"In general, they are taking simple views of how different parts of the brain work and are saying it is important to turn a particular part of the brain on when advertising, and therefore you should do more of this or that," Lieberman said. "For instance, they will say you want to activate the amygdala because that is the brain's emotion center. Typically they are not looking at the relationship between what happens in the brain when someone is exposed to an advertisement and what actually are the outcomes that you care about. For example, do people change their behavior? Does someone spread the message to others? Instead, they are giving generic analysis, and my guess is that the vast majority of the advice they are giving is not accurate.

"To really understand the relationship between the brain's responses to brands and persuasive materials and desirable outcomes, you actually have to measure the outcomes that are desirable and not just say what should work," he said. "There are many folks claiming to be neuroscientists who have read a little introductory neuroscience, and that is not enough expertise. It's almost infinitely more complicated than that."

Co-authors on the Journal of Neuroscience paper are Elliot Berkman, a UCLA graduate student of psychology in Lieberman's laboratory who will be an assistant professor of psychology at the University of Oregon this fall; Traci Mann, a professor of psychology at the University of Minnesota-Minneapolis who was formerly on UCLA's faculty; and Brittany Harrison, a former UCLA undergraduate student.

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Copycat Behavior in Children Is Universal

Copycat Behavior in Children Is Universal

  8:04:00 PM    Science Lover

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Children learn a great deal by imitating adults. A new study of Australian preschoolers and Kalahari Bushman children finds that a particular kind of imitation -- overimitation, in which a child copies everything an adult shows them, not just the steps that lead to some outcome -- appears to be a universal human activity, rather than something the children of middle-class parents pick up. The work helps shed light on how humans develop and transmit culture.

For the experiments, children were shown how to open a box -- but in a complicated way, with impractical actions thrown in. For example, the adult would drag a stick across a box, then use a stick to open the box by pulling on a knob -- which is a lot easier if you just use your fingers. Most of the children copied what the adults did, even if they'd been given the opportunity to play with the box first and figure out how it worked. This was just as true for Bushman children as for the Australian children. (Credit: iStockphoto)

Scientists "have been finding this odd effect where children will copy everything that they see an adult demonstrate to them, even if there are clear or obvious reasons why those actions would be irrelevant," says psychologist Mark Nielsen, of the University of Queensland in Australia. "It's something that we know that other primates don't do." If a chimpanzee is shown an irrelevant action, they won't copy it -- they'll skip right to the action that makes something happen.

But it's not clear that the results found in child psychology research apply to all people, Nielsen says. This research is usually done with children who live in Western cultures, whose parents are well educated and middle to upper class. And these parents are constantly teaching their children. But parents in indigenous cultures generally don't spend a lot of time teaching. "They may slow what they're doing if the child is watching, but it's not the kind of active instruction that's common in Western cultures," says Nielsen. So he teamed up with Keyan Tomaselli, an anthropologist at the University of KwaZulu-Natal in Durban, South Africa, who has worked for decades in Bushman communities in southern Africa. Their study is published in Psychological Science, a journal of the Association for Psychological Science.

For the experiments, the children were shown how to open a box -- but in a complicated way, with impractical actions thrown in. For example, the adult would drag a stick across a box, then use a stick to open the box by pulling on a knob -- which is a lot easier if you just use your fingers. Most of the children copied what the adults did, even if they'd been given the opportunity to play with the box first and figure out how it worked. This was just as true for Bushman children as for the Australian children.

But aren't the children just following the rules of what appears to be a game? "That kind of is the point," says Nielsen. "Perhaps not a game, but certainly, when I demonstrate the action, it's purposeful. So from the mind of a child, perhaps there's a reason why I'm doing this." This willingness to assume that an action has some unknown purpose, and to copy it, may be part of how humans develop and share culture, he says. "Really, we see these sorts of behaviors as being a core part of developing this human cultural mind, where we're so motivated to do things like those around us and be like those around us."

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