Category: Memory

Neuroscientists have found strong evidence that vivid memory and directly experiencing the real moment can trigger similar brain activation patterns.

The study, led by Baycrest's Rotman Research Institute (RRI), in collaboration with the University of Texas at Dallas, is one of the most ambitious and complex yet for elucidating the brain's ability to evoke a memory by reactivating the parts of the brain that were engaged during the original perceptual experience. Researchers found that vivid memory and real perceptual experience share "striking" similarities at the neural level, although they are not "pixel-perfect" brain pattern replications.

The study appears online this month in the Journal of Cognitive Neuroscience, ahead of print publication.

"When we mentally replay an episode we've experienced, it can feel like we are transported back in time and re-living that moment again," said Dr. Brad Buchsbaum, lead investigator and scientist with Baycrest's RRI. "Our study has confirmed that complex, multi-featured memory involves a partial reinstatement of the whole pattern of brain activity that is evoked during initial perception of the experience. This helps to explain why vivid memory can feel so real."

But vivid memory rarely fools us into believing we are in the real, external world — and that in itself offers a very powerful clue that the two cognitive operations don't work exactly the same way in the brain, he explained.

In the study, Dr. Buchsbaum's team used functional magnetic resonance imaging (fMRI), a powerful brain scanning technology that constructs computerized images of brain areas that are active when a person is performing a specific cognitive task. A group of 20 healthy adults (aged 18 to 36) were scanned while they watched 12 video clips, each nine seconds long, sourced from YouTube.com and Vimeo.com. The clips contained a diversity of content — such as music, faces, human emotion, animals, and outdoor scenery. Participants were instructed to pay close attention to each of the videos (which were repeated 27 times) and informed they would be tested on the content of the videos after the scan.

A subset of nine participants from the original group were then selected to complete intensive and structured memory training over several weeks that required practicing over and over again the mental replaying of videos they had watched from the first session. After the training, this group was scanned again as they mentally replayed each video clip. To trigger their memory for a particular clip, they were trained to associate a particular symbolic cue with each one. Following each mental replay, participants would push a button indicating on a scale of 1 to 4 (1 = poor memory, 4 = excellent memory) how well they thought they had recalled a particular clip.

Dr. Buchsbaum's team found "clear evidence" that patterns of distributed brain activation during vivid memory mimicked the patterns evoked during sensory perception when the videos were viewed — by a correspondence of 91% after a principal components analysis of all the fMRI imaging data.

The so-called "hot spots," or largest pattern similarity, occurred in sensory and motor association areas of the cerebral cortex — a region that plays a key role in memory, attention, perceptual awareness, thought, language and consciousness.

Dr. Buchsbaum suggested the imaging analysis used in his study could potentially add to the current battery of memory assessment tools available to clinicians. Brain activation patterns from fMRI data could offer an objective way of quantifying whether a patient's self-report of their memory as "being good or vivid" is accurate or not.

The study was funded with grants from the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada.

Too often our memory starts acting like a particularly porous sieve: all the important fragments that should be caught and preserved somehow just disappear. So armed with pencils and bolstered by caffeine, legions of adults, especially older adults, tackle crossword puzzles, acrostics, Sudoku and a host of other activities designed to strengthen their flagging memory muscles.

But maybe all they really need to do to cement new learning is to sit and close their eyes for a few minutes. In an article to be published in the journal Psychological Science, a publication of the Association for Psychological Science, psychological scientist Michaela Dewar and her colleagues show that memory can be boosted by taking a brief wakeful rest after learning something verbally new — so keep the pencil for phone numbers- and that memory lasts not just immediately but over a longer term.

"Our findings support the view that the formation of new memories is not completed within seconds," says Dewar. "Indeed our work demonstrates that activities that we are engaged in for the first few minutes after learning new information really affect how well we remember this information after a week."

In two separate experiments, a total of thirty-three normally aging adults between the ages of 61 and 87 were told two short stories and told to remember as many details as possible. Immediately afterward, they were asked to describe what happened in the story. Then they were given a 10-minute delay that consisted either of wakeful resting or playing a spot-the-difference game on the computer.

During the wakeful resting portion, participants were asked to just rest quietly with their eyes closed in a darkened room for 10 minutes while the experimenter left to "prepare for the next test." Participants could daydream or think about the story, or go through their grocery lists. It didn't matter what happened while their eyes were closed, only that they were undistracted by anything else and not receiving any new information.

When participants played the spot-the-difference game, they were presented with picture pairs on a screen for 30 seconds each and were instructed to locate two subtle differences in each pair and point to them. The task was chosen because it required attention but, unlike the story, it was nonverbal.

In one study, the participants were asked to recall both stories half an hour later and then a full week later. Participants remembered much more story material when the story presentation had been followed by a period of wakeful resting.

Dewar explains that there is growing evidence to suggest that the point at which we experience new information is "just at a very early stage of memory formation and that further neural processes have to occur after this stage for us to be able to remember this information at a later point in time."

We now live in a world where we are bombarded by new information and it crowds out recently acquired information. The process of consolidating memories takes a little time and the most important things that it needs are peace and quiet.

Stroboscopic training, performing a physical activity while using eyewear that simulates a strobe-like experience, has been found to increase visual short-term memory retention, and the effects lasted 24 hours.

Participants in a Duke University study engaged in physical activities, such as playing catch, while using either specialized eyewear that limits vision to only brief snapshots or while using eyewear with clear lenses that provides uninterrupted vision. Participants completed a computer-based visual memory test before and after the physical activities. Research participants came from the Duke community. Many were recruited from University-organized sports teams, including varsity-level players. The study found that participants who trained with the strobe eyewear gained a boost in visual memory abilities.

Participants completed a memory test that required them to note the identity of eight letters of the alphabet that were briefly displayed on a computer screen. After a variable delay, participants were asked to recall one of the eight letters. On easy-level trials, the recall prompt came immediately after the letters disappeared, but on more difficult trials, the prompt came as late as 2.5 seconds following the display. Because participants did not know which letter they would be asked to recall, they had to retain all of the items in memory.

"Humans have a memory buffer in their brain that keeps information alive for a certain short-lived period," said Greg Appelbaum, assistant professor of psychiatry at Duke University and first author of the study. "Wearing the strobe eyewear during the physical training seemed to boost the ability to retain information in this buffer."

The strobe eyewear disrupts vision by only allowing the user to see glimpses of the world. The user must adjust their visual processing in order to perform normally, and this adjustment produces a lingering benefit; once participants removed the strobe eyewear, there was an observed boost in their visual memory retention, which was found to last 24 hours.

Earlier work by Appelbaum and the project's senior researcher, Stephen Mitroff, had shown that stroboscopic training improves visual perception, including the ability to detect subtle motion cues and the processing of briefly presented visual information. Yet the earlier study had not determined how long the benefits might last.

"Our earlier work on stroboscopic training showed that it can improve perceptual abilities, but we don't know exactly how," says Mitroff, associate professor of psychology & neuroscience and member of the Duke Institute for Brain Sciences. "This project takes a big step by showing that these improved perceptual abilities are driven, at least in part, by improvements in visual memory."

"Improving human cognition is an important goal with so many benefits," said Appelbaum, also a member of the Duke Institute for Brain Sciences. "Interestingly, our findings demonstrate one way in which visual experience has the capacity to improve cognition."

Participants for the study came from the 2010-2011 Duke University men's and women's varsity soccer teams, Duke's 2010-2011 men's basketball team and members of the general Duke community. Mitroff reported that participants had little or no trouble with the stroboscopic training, and several participants later returned to inquire about how they could be involved as research assistants.

The research was supported by Nike SPARQ Sensory Performance, who designed the eyewear and is marketing it as Nike SPARQ Vapor Strobe. The study appears online July 19 in Attention, Perception, & Psychophysics.

Neuroscientists from Wayne State University and the Massachusetts Institute of Technology (MIT) are taking a deeper look into how the brain mechanisms for memory retrieval differ between adults and children. While the memory systems are the same in many ways, the researchers have learned that crucial functions with relevance to learning and education differ.

The team's findings were published on July 17, 2012, in the Journal of Neuroscience.

According to lead author Noa Ofen, Ph.D., assistant professor in WSU's Institute of Gerontology and Department of Pediatrics, cognitive ability, including the ability to learn and remember new information, dramatically changes between childhood and adulthood. This ability parallels with dramatic changes that occur in the structure and function of the brain during these periods.

In the study, "The Development of Brain Systems Associated with Successful Memory Retrieval of Scenes," Ofen and her collaborative team tested the development of neural underpinnings of memory from childhood to young adulthood. The team of researchers exposed participants to pictures of scenes and then showed them the same scenes mixed with new ones and asked them to judge whether each picture was presented earlier. Participants made retrieval judgments while researchers collected images of their brains with magnetic resonance imaging (MRI).

Using this method, the researchers were able to see how the brain remembers. "Our results suggest that cortical regions related to attentional or strategic control show the greatest developmental changes for memory retrieval," said Ofen.

The researchers said that older participants used the cortical regions more than younger participants when correctly retrieving past experiences.

"We were interested to see whether there are changes in the connectivity of regions in the brain that support memory retrieval," Ofen added. "We found changes in connectivity of memory-related regions. In particular, the developmental change in connectivity between regions was profound even without a developmental change in the recruitment of those regions, suggesting that functional brain connectivity is an important aspect of developmental changes in the brain."

This study marks the first time that the development of connectivity within memory systems in the brain has been tested, and the results suggest that the brain continues to rearrange connections to achieve adult-like performance during development.

Ofen and her research team plan to continue research in this area, focused on modeling brain network connectivity, and applying these methods to study abnormal brain development.

— When humans learn, their brains relate new information with past experiences to derive new knowledge, according to psychology research from The University of Texas at Austin.

The study, led by Alison Preston, assistant professor of psychology and neurobiology, shows this memory-binding process allows people to better understand new concepts and make future decisions. The findings could lead to better teaching methods, as well as treatment of degenerative neurological disorders, such as dementia, Preston says.

"Memories are not just for reflecting on the past; they help us make the best decisions for the future," says Preston, a research affiliate in the Center for Learning and Memory, which is part of the university's College of Natural Sciences. "Here, we provide a direct link between these derived memories and the ability to make novel inferences."

The paper was published online in July in the journal Neuron. The authors include University of Texas at Austin researchers Dagmar Zeithamova and April Dominick.

In the study, 34 subjects were shown a series of paired images composed of different elements (for example, an object and an outdoor scene). Each of the paired images would then reappear in more presentations. A backpack, paired with a horse in the first presentation, would appear alongside a field in a later presentation. The overlap between the backpack and outdoor scenery (horse and field) would cause the viewer to associate the backpack with the horse and field. The researchers used this strategy to see how respondents would delve back to a recent memory while processing new information.

Using functional Magnetic Resonance Imaging (fMRI) equipment, the researchers were able to look at the subjects' brain activity as they looked at image presentations. Using this technique, Preston and her team were able to see how the respondents thought about past images while looking at overlapping images. For example, they studied how the respondents thought about a past image (a horse) when looking at the backpack and the field. The researchers found the subjects who reactivated related memories while looking at overlapping image pairs were able to make associations between individual items (i.e. the horse and the field) despite the fact that they had never studied those images together.

To illustrate the ways in which this cognitive process works, Preston describes an everyday scenario.

Imagine you see a new neighbor walking a Great Dane down the street. At a different time and place, you may see a woman walking the same dog in the park. When experiencing the woman walking her dog, the brain conjures images of the recent memory of the neighbor and his Great Dane, causing an association between the dog walkers to be formed in memory. The derived relationship between the dog walkers would then allow you to infer the woman is also a new neighbor even though you have never seen her in your neighborhood.

"This is just a simple example of how our brains store information that goes beyond the exact events we experience," Preston says. "By combining past events with new information, we're able to derive new knowledge and better anticipate what to expect in the future."

During the learning tasks, the researchers were able to pinpoint the brain regions that work in concert during the memory-binding process. They found the hippocampal-ventromedial prefrontal cortex (VMPFC) circuit is essential for binding reactivated memories with current experience.

NewsPsychology (June 28, 2012) — We’ve all heard that eating fish is good for our brains and memory. But what is it about DHA, an omega-3 fatty acid found in fish, that makes our memory sharper?

Researchers with the Faculty of Medicine & Dentistry discovered a possible explanation and just published their findings in the peer-reviewed journal Applied Physiology, Nutrition, and Metabolism.

Principal investigator Yves Sauve and his team discovered lab models fed a high-DHA diet had 30 per cent higher levels of DHA in the memory section of the brain, known as the hippocampus, when compared to animal models on a regular, healthy diet.

“We wanted to find out how fish intake improves memory,” says Sauve, a medical researcher at the University of Alberta who works in the department of physiology, the department of ophthalmology and the Centre for Neuroscience.

“What we discovered is that memory cells in the hippocampus could communicate better with each other and better relay messages when DHA levels in that region of the brain were higher. This could explain why memory improves on a high-DHA diet.”

Sauve noted it is a key finding that when a diet is supplemented with DHA, that additional stores of the omega-3 fatty acid are deposited in the brain. His team confirmed this finding, a discovery other labs have noted as well.

Supplementing your diet with DHA, such as increasing fish intake or taking supplements, could prevent declining DHA levels in the brain as we age, says Sauve.

This research was funded by Alberta Innovates — Health Solutions.

Earlier this year, Sauve and other colleagues discovered DHA prevents the accumulation of a toxic molecule at the back of the eye that causes age-related vision loss. He is continuing his research in this area.

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Story Source:

The above story is reprinted from materials provided by University of Alberta Faculty of Medicine & Dentistry.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Steve Connor, Gustavo Tenorio, Michael Tom Clandinin, Yves Sauv. DHA supplementation enhances high-frequency, stimulation-induced synaptic transmission in mouse hippocampus. Applied Physiology, Nutrition, and Metabolism, 20 June 2012 DOI: 10.1139/h2012-062

Researchers have long been interested in discovering the ways that human brains represent thoughts through a complex interplay of electrical signals. Recent improvements in brain recording and statistical methods have given researchers unprecedented insight into the physical processes under-lying thoughts. For example, researchers have begun to show that it is possible to use brain recordings to reconstruct aspects of an image or movie clip someone is viewing, a sound someone is hearing or even the text someone is reading.

A new study by University of Pennsylvania and Thomas Jefferson University scientists brings this work one step closer to actual mind reading by using brain recordings to infer the way people organize associations between words in their memories.

The research was conducted by professor Michael J. Kahana of the Department of Psychology in Penn's School of Arts and Sciences and graduate student Jere-my R. Manning, then a member of the Neuroscience Graduate Group in Penn's Perelman School of Medicine. They collaborated with other members of Kahana's laboratory, as well as with research faculty at Thomas Jefferson University Hospital.

Their study was published in The Journal of Neuroscience.

The brain recordings necessary for the study were made possible by the fact that the participants were epilepsy patients who volunteered for the study while awaiting brain surgery. These participants had tiny electrodes implanted in their brains, which allowed researchers to precisely observe electrical signals that would not have been possible to measure outside the skull. While recording these electrical signals, the researchers asked the participants to study lists of 15 randomly chosen words and, a minute later, to repeat the words back in which-ever order they came to mind.

The researchers examined the brain recordings as the participants studied each word to home in on signals in the participant' brains that reflected the meanings of the words. About a second before the participants recalled each word, these same "meaning signals" that were identified during the study phase were spontaneously reactivated in the participants' brains.

Because the participants were not seeing, hearing or speaking any words at the times these patterns were reactivated, the researchers could be sure they were observing the neural signatures of the participants' self-generated, internal thoughts.

Critically, differences across participants in the way these meaning signals were reactivated predicted the order in which the participants would recall the words. In particular, the degree to which the meaning signals were reactivated before recalling each word reflected each participant's tendency to group similar words (like "duck" and "goose") together in their recall sequence. Since the participants were instructed to say the words in the order they came to mind, the specific se-quence of recalls a participant makes provides insights into how the words were organized in that participant's memory.

In an earlier study, Manning and Kahana used a similar technique to predict participants' tendencies to organize learned information according to the time in which it was learned. Their new study adds to this research by elucidating the neural signature of organizing learned information by meaning.

"Each person's brain patterns form a sort of 'neural fingerprint' that can be used to read out the ways they organize their memories through associations between words," Manning said.

The techniques the researchers developed in this study could also be adapted to analyze many different ways of mentally organizing studied information.

"In addition to looking at memories organized by time, as in our previous study, or by meaning, as in our current study, one could use our technique to identify neural signatures of how individuals organize learned information according to appearance, size, texture, sound, taste, location or any other measurable property," Manning said.

Such studies would paint a more complete picture of a fundamental aspect of human behavior.

"Spontaneous verbal recall is a form of memory that is both pervasive in our lives and unique to the human species," Kahana said. "Yet, this aspect of human memory is the least well understood in terms of brain mechanisms. Our data show a direct correspondence between patterns of brain activity and the meanings of individual words and show how this neural representation of meaning predicts the way in which one item cues another during spontaneous recall.

"Given the critical role of language in human thought and communication, identifying a neural representation that reflects the meanings of words as they are spontaneously recalled brings us one step closer to the elusive goal of mapping thoughts in the human brain."

 Most of us have experienced it. You are introduced to someone, only to forget his or her name within seconds. You rack your brain trying to remember, but can't seem to even come up with the first letter. Then you get frustrated and think, "Why is it so hard for me to remember names?"

You may think it's just how you were born, but that's not the case, according to Kansas State University's Richard Harris, professor of psychology. He says it's not necessarily your brain's ability that determines how well you can remember names, but rather your level of interest.

"Some people, perhaps those who are more socially aware, are just more interested in people, more interested in relationships," Harris said. "They would be more motivated to remember somebody's name."

This goes for people in professions like politics or teaching where knowing names is beneficial. But just because someone can't remember names doesn't mean they have a bad memory.

"Almost everybody has a very good memory for something," Harris said.

The key to a good memory is your level of interest, he said. The more interest you show in a topic, the more likely it will imprint itself on your brain. If it is a topic you enjoy, then it will not seem like you are using your memory.

For example, Harris said a few years ago some students were playing a geography game in his office. He started to join in naming countries and their capitals. Soon, the students were amazed by his knowledge, although Harris didn't understand why. Then it dawned on him that his vast knowledge of capitals didn't come from memorizing them from a map, but rather from his love of stamps and learning their whereabouts.

"I learned a lot of geographical knowledge without really studying," he said.

Harris said this also explains why some things seem so hard to remember — they may be hard to understand or not of interest to some people, such as remembering names.

Harris said there are strategies for training your memory, including using a mnemonic device.

"If somebody's last name is Hefty and you notice they're left-handed, you could remember lefty Hefty," he said.

Another strategy is to use the person's name while you talk to them — although the best strategy is simply to show more interest in the people you meet, he said.

Need to do some serious multitasking? Some training in meditation beforehand could make the work smoother and less stressful, new research from the University of Washington shows.

Work by UW Information School professors David Levy and Jacob Wobbrock suggests that meditation training can help people working with information stay on tasks longer with fewer distractions and also improves memory and reduces stress.

Their paper was published in the May edition of Proceedings of Graphics Interface.

Levy, a computer scientist, and Wobbrock, a researcher in human-computer interaction, conducted the study together with Information School doctoral candidate Marilyn Ostergren and Alfred Kaszniak, a neuropsychologist at the University of Arizona.

"To our knowledge, this is the first study to explore how meditation might affect multitasking in a realistic work setting," Levy said.

The researchers recruited three groups of 12-15 human resource managers for the study. One group received eight weeks of mindfulness-based meditation training; another received eight weeks of body relaxation training. Members of the third, a control group, received no training at first, then after eight weeks were given the same training as the first group.

Before and after each eight-week period, the participants were given a stressful test of their multitasking abilities, requiring them to use email, calendars, instant-messaging, telephone and word-processing tools to perform common office tasks. Researchers measured the participants' speed, accuracy and the extent to which they switched tasks. The participants' self-reported levels of stress and memory while performing the tasks were also noted.

The results were significant: The meditation group reported lower levels of stress during the multitasking test while those in the control group or who received only relaxation training did not. When the control group was given meditation training, however, its members reported lower stress during the test just as had the original meditation group.

The meditation training seemed to help participants concentrate longer without their attention being diverted. Those who meditated beforehand spent more time on tasks and switched tasks less often, but took no longer to complete the overall job than the others, the researchers learned.

No such change occurred with those who took body relaxation training only, or with the control group. After the control group's members underwent meditation training, however, they too spent longer on their tasks with less task switching and no overall increase in job completion time.

After training, both the meditators and those trained in relaxation techniques showed improved memory for the tasks they were performing. The control group did not, until it too underwent the meditation training.

"Many research efforts at the human-technology boundary have attempted to create technologies that augment human abilities," Wobbrock said. "This meditation work is unusual in that it attempts to augment human abilities not through technology but because of technology — because of the demands technology places on us and our need to cope with those demands."

Levy added: "We are encouraged by these first results. While there is increasing scientific evidence that certain forms of meditation increase concentration and reduce emotional volatility and stress, until now there has been little direct evidence that meditation may impart such benefits for those in stressful, information-intensive environments."

One of the brain's jobs is to help us figure out what's important enough to be remembered. Scientists at Yerkes National Primate Research Center, Emory University have achieved some insight into how fleeting experiences become memories in the brain.

Their experimental system could be a way to test or refine treatments aimed at enhancing learning and memory, or interfering with troubling memories. The results were published this week in the Journal of Neuroscience.

The researchers set up a system where rats were exposed to a light followed by a mild shock. A single light-shock event isn't enough to make the rat afraid of the light, but a repeat of the pairing of the light and shock is, even a few days later.

"I describe this effect as 'priming'," says the first author of the paper, postdoctoral fellow Ryan Parsons. "The animal experiences all sorts of things, and has to sort out what's important. If something happens just once, it doesn't register. But twice, and the animal remembers."

Parsons was working with Michael Davis, PhD, Robert W. Woodruff professor of psychiatry and behavioral sciences at Emory University School of Medicine, who has been studying the molecular basis for fear memory for several years.

Even though a robust fear memory was not formed after the first priming event, at that point Parsons could already detect chemical changes in the amygdala, part of the brain critical for fear responses. Long term memory formation could be blocked by infusing a drug into the amygdala. The drug inhibits protein kinase A, which is involved in the chemical changes Parsons observed.

It is possible to train rats to become afraid of something like a sound or a smell after one event, Parsons says. However, rats are less sensitive to light compared with sounds or smells, and a relatively mild shock was used.

Fear memories only formed when shocks were paired with light, instead of noise or nothing at all, for both the priming and the confirmation event. Parsons measured how afraid the rats were by gauging their "acoustic startle response" (how jittery they were in response to a loud noise) in the presence of the light, compared to before training began.

Scientists have been able to study the chemical changes connected with the priming process extensively in neurons in culture dishes, but not as much in live animals. The process is referred to as "metaplasticity," or how the history of the brain's experiences affects its readiness to change and learn.

"This could be a good model for dissecting the mechanisms involved in learning and memory," Parsons says. "We're going to be able to look at what's going on in that first priming event, as well as when the long-term memory is triggered."

"We believe our findings might help explain how events are selected out for long-term storage from what is essentially a torrent of information encountered during conscious experience," Parsons and Davis write in their paper.

The research was supported by the National Institute of Mental Health (R37 MH047840 and F32 MH090700).

Reference: R.G. Parsons and M. Davis. A metaplasticity-like mechanism supports the selection of fear memories: role of protein kinase A in the amygdala. J. Neurosci 32: 7843-7851 (2012).