Sleep selectively stores useful memories: brain evaluates information based on future expectations
February 1, 2011
Science Daily/Society for Neuroscience
After a good night's sleep, people remember information better when they know it will be useful in the future, according to a new study in the Feb. 2 issue of The Journal of Neuroscience. The findings suggest that the brain evaluates memories during sleep and preferentially retains the ones that are most relevant.
"Our results show that memory consolidation during sleep indeed involves a basic selection process that determines which of the many pieces of the day's information is sent to long-term storage," Born said. "Our findings also indicate that information relevant for future demands is selected foremost for storage."
Some, but not all, of the volunteers were allowed to sleep between the time they learned the tasks and the tests. As the authors expected, the people who slept performed better than those who didn't. But more importantly, only the people who slept and knew a test was coming had substantially improved memory recall.
The researchers also recorded electroencephalograms (EEG) from the individuals who were allowed to sleep. They found an increase in brain activity during deep or "slow wave" sleep when the volunteers knew they would be tested for memory recall.
"The more slow wave activity the sleeping participants had, the better their memory was during the recall test 10 hours later," Born said. Scientists have long thought that sleep is important in memory consolidation. The authors suggest that the brain's prefrontal cortex "tags" memories deemed relevant while awake and the hippocampus consolidates these memories during sleep.
http://www.sciencedaily.com/releases/2011/02/110201172603.htm
Memory Links to 40 Winks
July 6, 2010
Science Daily/Washington University in St. Louis
When it comes to executing items on tomorrow's to-do list, it's best to think it over, then "sleep on it," say psychologists at Washington University in St. Louis.
People who sleep after processing and storing a memory carry out their intentions much better than people who try to execute their plan before getting to sleep. The researchers have shown that sleep enhances our ability to remember to do something in the future, a skill known as prospective memory.
Moreover, researchers studying the relationship between memory and sleep say that our ability to carry out our intentions is not so much a function of how firmly that intention has been embedded in our memories. Rather, the trigger that helps carry out our intentions is usually a place, situation or circumstance -- some context encountered the next day -- that sparks the recall of an intended action.
The researchers found that participants who tested in the morning following sleep overwhelmingly performed the prospective memory task better in the semantic category test, or context, than in the other two, and they found no such correlation in the group who tested sleepless.
The crux of the finding rests on the fact that the prospective memory instruction was given right after the semantic category practice. In this context, those who slept remembered the prospective memory intention better than in the other categories.
"Sleep promoted the remembering to do the prospective memory task when that one context was present, but not when some other context was present," McDaniel says. "That's because of temporal contiguity -- the fact that the participants were told to hit that 'Q' button right after they were exposed to the semantic category context.
"The idea is that the semantic category test is weakly associated with the prospective memory intention -- it's weakly floating around in the mind and becomes weakly associated with the prospective memory test," McDaniel says.
To return to the colleague and message analogy, because before sleeping you remembered you had a message to deliver to your colleague and you would see him in the conference room tomorrow, sleep enhances the likelihood that you will tell him in the conference room, but not in some other context, the office, elevator, the mail room, for example.
The researchers believe that the prospective memory process occurs during slow wave sleep -- an early pattern in the sleep cycle -- involving communication between the hippocampus and cortical regions. The hippocampus is very important in memory formation and reactivation and the cortical regions are keys to storing memories.
"We think that during slow wave sleep the hippocampus is reactivating these recently learned memories, taking them up and placing them in long-term storage regions in the brain," Scullin says. "The physiology of slow wave sleep seems very conducive to this kind of memory strengthening."
http://www.sciencedaily.com/releases/2010/06/100630162359.htm
To Learn Better, Take a Nap (and Don't Forget to Dream)
April 26, 2010
Science Daily/Beth Israel Deaconess Medical Center
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.
"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."
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?'"
http://www.sciencedaily.com/releases/2010/04/100422153753.htm
Memory May Decline Rapidly Even in Stage Before Alzheimer's Disease
March 23, 2010
Science Daily/American Academy of Neurology
Memory and thinking skills may decline rapidly for people who have mild cognitive impairment, which is the stage before Alzheimer's disease when people have mild memory problems but no dementia symptoms, and even more rapidly when dementia begins, which is when Alzheimer's disease is usually diagnosed.
"These results show that we need to pay attention to this time before Alzheimer's disease is diagnosed, when people are just starting to have problems forgetting things," said study author Robert S. Wilson, PhD, of Rush University Medical Center in Chicago.
"The changes in rate of decline occur as the brain atrophies due to the disease, first mainly in the hippocampus during the initial symptomatic stage, referred to as mild cognitive impairment, then in the temporal, parietal and frontal cortex during the dementing illness phase of Alzheimer's disease," said David S. Knopman, MD, of the Mayo Clinic in Rochester, Minn., and Fellow of the American Academy of Neurology, who wrote an editorial accompanying the article.
http://www.sciencedaily.com/releases/2010/03/100322171008.htm
Direct Evidence of Role of Sleep in Memory Formation is Uncovered
September 16, 2009
Science Daily/Rutgers University
A research team has pinpointed for the first time the mechanism that takes place during sleep that causes learning and memory formation to occur. The team has determined that short transient brain events, called “sharp wave ripples,” are responsible for consolidating memory and transferring the learned information from the hippocampus to the neocortex, where long-term memories are stored.
A Rutgers University, Newark and Collége de France, Paris research team has pinpointed for the first time the mechanism that takes place during sleep that causes learning and memory formation to occur.
It’s been known for more than a century that sleep somehow is important for learning and memory. Sigmund Freud further suspected that what we learned during the day was “rehearsed” by the brain during dreaming, allowing memories to form. And while much recent research has focused on the correlative links between the hippocampus and memory consolidation, what had not been identified was the specific processes that cause long-term memories to form.
“This is the first example that if a well-defined pattern of activity in the brain is reliably and selectively eliminated, it results in memory deficit; a demonstration that this specific brain pattern is the cause behind long-term memory formation,” says Buzsaki.
The research also represents a move toward a new direction in neuroscience research. While previous research largely has focused on correlating behavior with specific brain events through electroencephalogram, neuronal spiking and functional magnetic resonance imaging studies, increasingly researchers are challenging those correlations as they seek to identify the specific process or processes that cause certain events and behaviors to take place.
http://www.sciencedaily.com/releases/2009/09/090915174506.htm
Sleep Helps Reduce Errors in Memory
September 11, 2009
Science Daily/Michigan State University
Sleep may reduce mistakes in memory, according to a first-of-its-kind study led by a cognitive neuroscientist at Michigan State University.
The findings, which appear in the September issue of the journal Learning & Memory, have practical implications for everyone from students flubbing multiple choice tests to senior citizens confusing their medications, said Kimberly Fenn, principal investigator and MSU assistant professor of psychology.
“We know older individuals generally have worse memory performance than younger individuals. We also know from other research that elderly individuals tend to be more prone to false memories,” Fenn said. “Given the work we’ve done it’s possible that sleep may actually help them to reject this false information. And potentially this could help to improve their quality of life in some way.”
http://www.sciencedaily.com/releases/2009/09/090910114136.htm
Chronic Insomnia Requires Increased Brain Activation to Maintain Daily Function
June 12, 2009
Science Daily/American Academy of Sleep Medicine
Patients suffering from chronic primary insomnia have higher levels of brain activation compared to normal sleepers during a working memory test.
According to a research abstract that will be presented on June 9, at Sleep 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies, patients suffering from chronic primary insomnia (PIs) have higher levels of brain activation compared to normal sleepers during a working memory test.
Results show that PIs use increased brain activation relative to good sleepers during the working memory task, particularly in areas responsible for visual-spatial attention and coordination of cognitive processes. This activation may explain how PIs maintain performance on the task despite their sleep difficulties. PIs also were found to have decreased activation in visual and motor areas, which may suggest that PIs have higher baseline activation in these regions relative to good sleepers.
http://www.sciencedaily.com/releases/2009/06/090609072811.htm
Tooth loss linked to slowing mind, body
December 18, 2014
Science Daily/University College London
The memory and walking speeds of adults who have lost all of their teeth decline more rapidly than in those who still have some of their own teeth, finds new research.
The association between total tooth loss and memory was explained after the results of a study were fully adjusted for a wide range of factors, such as sociodemographic characteristics, existing health problems, physical health, health behaviors, such as smoking and drinking, depression, relevant biomarkers, and particularly socioeconomic status. However, after adjusting for all possible factors, people without teeth still walked slightly slower than those with teeth.
These links between older adults in England losing all natural teeth and having poorer memory and worse physical function 10 years later were more evident in adults aged 60 to 74 years than in those aged 75 and older.
"Tooth loss could be used as an early marker of mental and physical decline in older age, particularly among 60-74 year-olds," says lead author Dr Georgios Tsakos (UCL Epidemiology & Public Health). "We find that common causes of tooth loss and mental and physical decline are often linked to socioeconomic status, highlighting the importance of broader social determinants such as education and wealth to improve the oral and general health of the poorest members of society.
"Regardless of what is behind the link between tooth loss and decline in function, recognising excessive tooth loss presents an opportunity for early identification of adults at higher risk of faster mental and physical decline later in their life. There are many factors likely to influence this decline, such as lifestyle and psychosocial factors, which are amenable to change."
Science Daily/SOURCE :http://www.sciencedaily.com/releases/2014/12/141218210023.htm