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+---- Thread: Memory is not stored in one place, all in Images (/Thread-Memory-is-not-stored-in-one-place-all-in-Images)
Memory is not stored in one place, all in Images - John Nicholson - 13-11-2010
[SIZE="6"][COLOR="DarkRed"]Damage to Prefrontal Cortex Compensated by Intact Areas; 'Phantom' Images Stored in Flexible Network Throughout Brain
ScienceDaily (Nov. 5, 2010) — Brain research over the past 30 years has shown that if a part of the brain controlling movement or sensation or language is lost because of a stroke or injury, other parts of the brain can take over the lost function -- often as well as the region that was lost.
New research at the University of California, Berkeley, shows that this holds true for memory and attention as well, though -- at least for memory -- the intact brain helps out only when needed and conducts business as usual when it's not.[/COLOR][/SIZE]
[SIZE="5"][COLOR="DarkGreen"]These results support the hypothesis that memory is not stored in one place, but rather, is distributed in many regions of the brain, which means that damage to one storage area is easier to compensate for.
"It's not just specific regions, but a whole network, that's supporting memory," said Bradley Voytek, a UC Berkeley postdoctoral fellow in the Helen Wills Neuroscience Institute and first author of two recent journal articles describing EEG (electroencephalogram) studies of people with strokes. Voytek recently completed his Ph.D. in neuroscience at UC Berkeley.
"The view has always been, if you lose point A, point B will be on all the time to take over," said co-author Dr. Robert Knight, UC Berkeley professor of psychology and head of the Wills Institute. "Brad has shown that's not true. It actually only comes on if it's needed.
"Most of the time, it acts like a normal piece of brain tissue. It only kicks into hyperdrive when the bad part of the brain is particularly challenged, and it does it in less than a second. This is a remarkably fluid neural plasticity, but it isn't the standard 'B took over for A,' it's really 'B will take over if and when needed.'"
One of the papers, published Nov. 3 in the online edition of Neuron and scheduled for the Nov. 4 print issue of the journal, describes a study of stroke patients who have lost partial function in their prefrontal cortex, the area at the top front of each hemisphere of the brain that governs memory and attention.[/COLOR][/SIZE][SIZE="4"]Voytek put electrodes on the scalps of six stroke patients as well as six controls with normal prefrontal cortex function, and showed each patient a series of pictures to test his or her ability to remember images for a brief time, so-called visual working memory. Visual working memory is what allows us to compare two objects, keeping one in memory while we look at another, as when we choose the ripest of two bananas.
"We presented each subject with a really quick flash of a visual stimulus and then showed them a second one a little while later, and they had to say whether it was the same as the first," Voytek explained. "The idea is that you're building a representation of your visual world somehow in your brain -- and we don't know how that happens -- so that later you can compare this internal phantom representation you're holding in your mind to a real world visual stimulus, something you actually see. These patients can't do that as well."
EEGs provide millisecond measurements of brain activity, though they do not pinpoint active areas as precisely as other techniques, such as functional magnetic resonance imaging (fMRI). On the other hand, fMRI averages brain activity over seconds, making it impossible to distinguish split-second brain processes or even tell which occur first.
The neuroscientists discovered that when images were shown to the eye opposite the lesion (output of the left eye goes to the right hemisphere, and vice versa), the damaged prefrontal cortex did not respond, but the intact prefrontal cortex on the same side as the image responded within 300 to 600 milliseconds.
"EEG, which is very good for looking at the timing of activity in the brain, showed that part of the brain is compensating on a subsecond basis," Voytek said. "It is very rapid compensation: Within a second of challenging the bad side, the intact side of the brain is coming online to pick up the slack."
"This has implications for what physicians measure to see if there's effective recovery after stroke," Knight said, "and suggests that you can take advantage of this to train the area you would like to take over from a damaged area instead of just globally training the brain."
In a second paper that appeared online Oct. 4 in the journal Proceedings of the National Academy of Sciences, Voytek and Knight looked at visual working memory in patients with damage not only to the prefrontal cortex, but also to the basal ganglia. The basal ganglia are a pair of regions directly below the brain's cortex that are involved in motor control and learning and that are impaired in patients with Parkinson's disease.
The patients with stroke damage to the prefrontal cortex had, as suspected, problems when images were presented to the eye on the side opposite the lesion. Those with basal ganglia damage, however, had problems with visual working memory no matter which part of the visual field was shown the image.
"The PNAS paper shows that the basal ganglia lesions cause a more broad network deficit, whereas the prefrontal cortex lesions cause a more within-hemisphere deficit in memory," Voytek said. "This demonstrates, again, that memory is a network phenomenon rather than a specifically regional phenomenon.""If you take out one basal ganglia, the logic would be that you would be Parkinsonian on half your body. But you're not," Knight said. "One basal ganglia on one side is able to somehow control fluid movement on both sides."
"Brad's data show that for cognitive control, it's just the opposite. One small basal ganglia lesion on one side has global effects on both sides of your body," he added. "This really points out that for this deep subcortical basal ganglia area, you need all of it to function normally. I don't think anybody would have really suspected that."
Knight hopes to conduct follow up studies using direct recordings from electrodes in the brain to further explore the various brain regions involved in visual memory and other types of memory and attention governed by the prefrontal cortex.
"Cognition and memory are the highest forms of human behavior," Knight said. "It is not just about raising or lowering your hand, or whether you can or cannot see. These are the things that make us human, and that is what makes it so interesting for us."
Other coauthors of the Neuron paper are Matar Davis and Elena Yago of UC Berkeley's Helen Wills Neuroscience Institute; Francisco Barceló of the Institut Universitari d'Investigació en Ciències de la Salut at the Universitat de les Illes Balears in Palma de Mallorca, Spain; and Edward K. Vogel of the University of Oregon in Eugene.
The work was supported by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health, and by an American Psychological Association Diversity Program in Neuroscience grant to Voytek.[/SIZE]
:pcprob:
Memory is not stored in one place, all in Images - John Nicholson - 15-11-2010
[SIZE="6"][COLOR="DarkRed"]Scientists Find Learning in the Visual Brain
ScienceDaily (Nov. 12, 2010) — A team of researchers from the University of Minnesota's College of Liberal Arts and College of Science and Engineering have found that an early part of the brain's visual system rewires itself when people are trained to perceive patterns, and have shown for the first time that this neural learning appears to be independent of higher order conscious visual processing.[/COLOR][/SIZE]
[SIZE="4"]The researchers' findings could help shape training programs for people who must learn to detect subtle patterns quickly, such as doctors reading X-rays or air traffic controllers monitoring radars. In addition, they appear to offer a resolution to a long-standing controversy surrounding the learning capabilities of the brain's early (or low-level) visual processing system.
The study by lead author Stephen Engel, a psychology professor in the College of Liberal Arts, is published in the Nov. 10 issue of the Journal of Neuroscience.
"We've basically shown that learning can happen in the earliest stages of visual processing in the brain," Engel said.
The researchers looked at how well subjects could identify a faint pattern of bars on a computer screen that continuously decreased in faintness. They found that over a period of 30 days, subjects were able to recognize fainter and fainter patterns. Before and after this training, they measured brain responses using EEG, which records electrical activity along the scalp produced by the firing of neurons within the brain.
"We discovered that learning actually increased the strength of the EEG signal," Engel said. "Critically, the learning was visible in the initial EEG response that arose after a subject saw one of these patterns. Even a tiny fraction of a second after a pattern was flashed, subjects showed bigger responses in their brain."
In other words, this part of the brain shows local "plasticity," or flexibility, that seems independent of higher order processing, such as conscious visual processing or changes in visual attention. Such higher order processing would take time to occur and so its effects would not be seen in the earliest part of the EEG response.
Engel says these finding may also help adults with visual deficits such as lazy eye by accelerating the development of training procedures to improve the eye's capabilities.
The paper was co-authored by Min Bao, Department of Psychology, College of Liberal Arts, and Bin He, Lin Yang and Christina Rios, Department of Biomedical Engineering, College of Science and Engineering.
Echoes Discovered In Early Visual Brain Areas Play Role In Working Memory
ScienceDaily (Mar. 1, 2009) — Vanderbilt University researchers have discovered that early visual areas, long believed to play no role in higher cognitive functions such as memory, retain information previously hidden from brain studies. The researchers made the discovery using a new technique for decoding data from functional magnetic resonance imaging or fMRI. The findings are a significant step forward in understanding how we perceive, process and remember visual information.
The results were published Feb. 18 online by Nature.
"We discovered that early visual areas play an important role in visual working memory," Frank Tong, co-author of the research and an associate professor of psychology at Vanderbilt, said. "How do people maintain an active representation of what they have just seen moments ago? This has long been a conundrum in the literature.
"Before, we knew that early visual areas of the cerebral cortex that are the first to receive visual information were exquisitely tuned to process incoming visual signals from the eye, but not to store this information," Tong said. "We also knew that the higher-order brain areas responsible for memory lack the visual sensitivity of early brain areas, but somehow people are able to remember a visual pattern with remarkable precision for many seconds, actually, for as long as they keep thinking about that pattern. Our question was, where is this precise information being stored in the brain?
"Using a new technique to analyze fMRI data, we've found that the fine-scale activity patterns in early visual areas reveal a trace or something like an echo of the stimulus that the person is actively retaining, even though the overall activity in these areas is really weak after the stimulus is removed," Tong continued.
Research subjects were shown two examples of simple striped patterns at different orientations. They were then told to hold either one or the other of the orientations in their mind while being scanned using fMRI. Orientation has long been known to be one of the first and most basic pieces of visual information coded and processed by the brain."Through both evolution and learning, the visual system has developed the most efficient ways to code our natural environment, and the most efficient way to code any basic shape or contour is orientation," Tong said. "We used a decoding method to see if the activity patterns contained information about the remembered orientation, and we found that they do. By analyzing responses over several trials, we were able to accurately read out which of the two orientation patterns a subject was holding in his or her mind over 80 percent of the time."
The researchers found that these predictions held true even when the overall level of activity in these visual areas was very weak, no different than looking at a blank screen. This suggests that the act of remembering an image leaves some sort of faint echo or trace in these brain areas. These activity traces are weak but are quite detailed and rich in information.
"By doing these pattern analyses, we were able to find information that was hidden before. We do not know for sure, but it's possible that a lot of information in the brain might be hidden in such activity patterns," Tong said. "Using this decoding technique and others, neuroscientists might get a better understanding of how the brain represents specific cognitive states involving memory, reminiscing, or other visual experiences that do not obviously lead to a huge amount of activity in the visual areas."
Tong and Harrison are members of the Vanderbilt Vision Research Center. The research was supported with funds from the National Eye Institute, the National Institutes of Health, and the Natural Sciences and Engineering Research Council of Canada.[/SIZE]
Memory is not stored in one place, all in Images - John Nicholson - 15-11-2010
[SIZE="5"][COLOR="DarkRed"]Sleep Makes Your Memories Stronger, and Helps With Creativity
ScienceDaily (Nov. 12, 2010) — As humans, we spend about a third of our lives asleep. So there must be a point to it, right? Scientists have found that sleep helps consolidate memories, fixing them in the brain so we can retrieve them later. Now, new research is showing that sleep also seems to reorganize memories,[/COLOR][/SIZE] picking out the emotional details and reconfiguring the memories to help you produce new and creative ideas, according to the authors of an article in Current Directions in Psychological Science.
[SIZE="6"]"Sleep is making memories stronger," [/SIZE]says Jessica D. Payne of the University of Notre Dame, who co-wrote the review with Elizabeth A. Kensinger of Boston College. "It also seems to be doing something which I think is so much more interesting, and that is reorganizing and restructuring memories."
[SIZE="5"]Payne and Kensinger study what happens to memories during sleep, and they have found that a person tends to hang on to the most emotional part of a memory. For example, if someone is shown a scene with an emotional object, such as a wrecked car, in the foreground, they're more likely to remember the emotional object than, say, the palm trees in the background -- particularly if they're tested after a night of sleep. They have also measured brain activity during sleep and found that regions of the brain involved with emotion and memory consolidation are active.
"In our fast-paced society, one of the first things to go is our sleep," Payne says. "I think that's based on a profound misunderstanding that the sleeping brain isn't doing anything." The brain is busy. It's not just consolidating memories, it's organizing them and picking out the most salient information. She thinks this is what makes it possible for people to come up with creative, new ideas.
Payne has taken the research to heart. "I give myself an eight-hour sleep opportunity every night. I never used to do that -- until I started seeing my data," she says. People who say they'll sleep when they're dead are sacrificing their ability to have good thoughts now, she says. "We can get away with less sleep, but it has a profound effect on our cognitive abilities." Science News
Collecting Your Thoughts: You Can Do It in Your Sleep!
ScienceDaily (Nov. 2, 2010) — It is one thing to learn a new piece of information, such as a new phone number or a new word, but quite another to get your brain to file it away so it is available when you need it.
A new study published in the Journal of Neuroscience by researchers at the University of York and Harvard Medical School suggests that sleep may help to do both.
The scientists found that sleep helps people to remember a newly learned word and incorporate new vocabulary into their "mental lexicon."
During the study, which was funded by the Economic and Social Research Council, researchers taught volunteers new words in the evening, followed by an immediate test. The volunteers slept overnight in the laboratory while their brain activity was recorded using an electroencephalogram, or EEG. A test the following morning revealed that they could remember more words than they did immediately after learning them, and they could recognise them faster demonstrating that sleep had strengthened the new memories.
This did not occur in a control group of volunteers who were trained in the morning and re-tested in the evening, with no sleep in between. An examination of the sleep volunteers' brainwaves showed that deep sleep (slow-wave sleep) rather than rapid eye movement (REM) sleep or light sleep helped in strengthening the new memories.When the researchers examined whether the new words had been integrated with existing knowledge in the mental lexicon, they discovered the involvement of a different type of activity in the sleeping brain. Sleep spindles are brief but intense bursts of brain activity that reflect information transfer between different memory stores in the brain -- the hippocampus deep in the brain and the neocortex, the surface of the brain.
Memories in the hippocampus are stored separately from other memories, while memories in the neocortex are connected to other knowledge. Volunteers who experienced more sleep spindles overnight were more successful in connecting the new words to the rest of the words in their mental lexicon, suggesting that the new words were communicated from the hippocampus to the neocortex during sleep.
Co-author of the paper, Professor Gareth Gaskell, of the University of York's Department of Psychology, said: "We suspected from previous work that sleep had a role to play in the reorganisation of new memories, but this is the first time we've really been able to observe it in action, and understand the importance of spindle activity in the process."
These results highlight the importance of sleep and the underlying brain processes for expanding vocabulary. But the same principles are likely to apply to other types of learning.
Lead author, Dr Jakke Tamminen, said: "New memories are only really useful if you can connect them to information you already know. Imagine a game of chess, and being told that the rule governing the movement of a specific piece has just changed. That new information is only useful to you once you can modify your game strategy, the knowledge of how the other pieces move, and how to respond to your opponent's moves. Our study identifies the brain activity during sleep that organises new memories and makes those vital connections with existing knowledge."[/SIZE]
Memory is not stored in one place, all in Images - John Nicholson - 16-11-2010
[SIZE="7"][COLOR="darkred"]
Is all conscious memory in a natural visual form
YES
[/COLOR][/SIZE]To Learn Better, Take a Nap (and Don't Forget to Dream)YES
ScienceDaily (Apr. 26, 2010) — It is by now well established that sleep can be an important tool when it comes to enhancing memory and learning skills. And now, a new study sheds light on the role that dreams play in this important process.
Led by scientists at Beth Israel Deaconess Medical Center (BIDMC), the new findings suggest that dreams may be the sleeping brain's way of telling us that it is hard at work on the process of memory consolidation, integrating our recent experiences to help us with performance-related tasks in the short run and, in the long run, translating this material into information that will have widespread application to our lives. The study is reported in the April 22 On-line issue of Current Biology.
[SIZE="5"]"What's got us really excited, is that after nearly 100 years of debate about the function of dreams, this study tells us that dreams are the brain's way of processing, integrating and really understanding new information," explains senior author Robert Stickgold, PhD, Director of the Center for Sleep and Cognition at BIDMC and Associate Professor of Psychiatry at Harvard Medical School. "Dreams are a clear indication that the sleeping brain is working on memories at multiple levels, including ways that will directly improve performance."[/SIZE]
[SIZE="5"]At the outset, the authors hypothesized that dreaming about a learning experience during nonrapid eye movement (NREM) sleep would lead to improved performance on a hippocampus-dependent spatial memory task. (The hippocampus is a region of the brain responsible for storing spatial memory.)
To test this hypothesis, the investigators had 99 subjects spend an hour training on a "virtual maze task," a computer exercise in which they were asked to navigate through and learn the layout of a complex 3D maze with the goal of reaching an endpoint as quickly as possible. Following this initial training, participants were assigned to either take a 90-minute nap or to engage in quiet activities but remain awake. At various times, subjects were also asked to describe what was going through their minds, or in the case of the nappers, what they had been dreaming about. Five hours after the initial exercise, the subjects were retested on the maze task.
The results were striking.
The non-nappers showed no signs of improvement on the second test -- even if they had reported thinking about the maze during their rest period. Similarly, the subjects who napped, but who did not report experiencing any maze-related dreams or thoughts during their sleep period, showed little, if any, improvement. But, the nappers who described dreaming about the task showed dramatic improvement, 10 times more than that shown by those nappers who reported having no maze-related dreams.
"These dreamers described various scenarios -- seeing people at checkpoints in a maze, being lost in a bat cave, or even just hearing the background music from the computer game," explains first author Erin Wamsley, PhD, a postdoctoral fellow at BIDMC and Harvard Medical School. These interpretations suggest that not only was sleep necessary to "consolidate" the information, but that the dreams were an outward reflection that the brain had been busy at work on this very task.
Of particular note, say the authors, the subjects who performed better were not more interested or motivated than the other subjects. But, they say, there was one distinct difference that was noted.
"The subjects who dreamed about the maze had done relatively poorly during training," explains Wamsley. "Our findings suggest that if something is difficult for you, it's more meaningful to you and the sleeping brain therefore focuses on that subject -- it 'knows' you need to work on it to get better, and this seems to be where dreaming can be of most benefit."
Furthermore, this memory processing was dependent on being in a sleeping state. Even when a waking subject "rehearsed and reviewed" the path of the maze in his mind, if he did not sleep, then he did not see any improvement, suggesting that there is something unique about the brain's physiology during sleep that permits this memory processing.
"In fact," says Stickgold, "this may be one of the main goals that led to the evolution of sleep. If you remain awake [following the test] you perform worse on the subsequent task. Your memory actually decays, no matter how much you might think about the maze.
"We're not saying that when you learn something it is dreaming that causes you to remember it," he adds. "Rather, it appears that when you have a new experience it sets in motion a series of parallel events that allow the brain to consolidate and process memories."
Ultimately, say the authors, the sleeping brain seems to be accomplishing two separate functions: While the hippocampus is processing information that is readily understandable (i.e. navigating the maze), at the same time, the brain's higher cortical areas are applying this information to an issue that is more complex and less concrete (i.e. how to navigate through a maze of job application forms).
"Our [nonconscious] brain works on the things that it deems are most important," adds Wamsley. "Every day, we are gathering and encountering tremendous amounts of information and new experiences," she adds. "It would seem that our dreams are asking the question, 'How do I use this information to inform my life?'"
Study coauthors include BIDMC investigators Matthew Tucker, Joseph Benavides and Jessica Payne (currently of the University of Notre Dame).
This study was supported by grants from the National Institutes of Health.[/SIZE][SIZE="7"]Conformation of my research that the sleeping brain functions normally in regards to reasoning[/SIZE]