Posts Tagged Journal of Neuroscience
In a new area of study, researchers explore how brain mechanisms for memory retrieval differ between adults and children.
Neuroscientists from Wayne State University and the Massachusetts Institute of Technology have discovered that while the memory systems are the same in many ways, the aging process appears to impart important differences in how we learn and respond to education.
Noa Ofen, Ph.D., an assistant professor in WSU’s Institute of Gerontology and Department of Pediatrics, says that 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, Ofen and her collaborative team tested the development of neural foundations of memory from childhood to young adulthood.
Researchers did this by exposing participants to pictures of scenes and then showing them the same scenes mixed with new ones. They then 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.
This finding suggests that older participants use the cortical regions of the brain to retrieve past memories more so than younger participants.
“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.”
Researchers say this study is unique as it is the first time that the development of connectivity within memory systems in the brain has been tested.
Findings suggest the brain continues to rearrange connections to achieve adult-like performance during development.
Future studies by Ofen and her research team will focus on modeling brain network connectivity, and applying these methods to study abnormal brain development.
The team’s findings are published in the Journal of Neuroscience.
Source: Wayne State University
5 mind-bending facts about dreams
By Jeanna Bryner
When your head hits the pillow, for many it’s lights out for the conscious part of you. But the cells firing in your brain are very much awake, sparking enough energy to produce the sometimes vivid and sometimes downright haunted dreams that take place during the rapid-eye-movement stage of your sleep.
Why do some people have nightmares while others really spend their nights in bliss? Like sleep, dreams are mysterious phenomena. But as scientists are able to probe deeper into our minds, they are finding some of those answers.
Here’s some of what we know about what goes on in dreamland.
1. Violent dreams can be a warning sign
As if nightmares weren’t bad enough, a rare sleep disorder — called REM sleep behavior disorder — causes people to act out their dreams, sometimes with violent thrashes, kicks and screams. Such violent dreams may be an early sign of brain disorders down the line, including Parkinson’s disease and dementia, according to research published online July 28, 2010, in the journal Neurology. The results suggest the incipient stages of these neurodegenerative disorders might begin decades before a person, or doctor, knows it.
2. Night owls have more nightmares
Staying up late has its perks, but whimsical dreaming is not one of them. Research published in 2011 in the journal Sleep and Biological Rhythms, revealed that night owls are more likely than their early-bird counterparts to experience nightmares.
In the study 264 university students rated how often they experienced nightmares on a scale from 0 to 4, never to always, respectively. The stay-up-late types scored, on average, a 2.10, compared with the morning types who averaged a 1.23. The researchers said the difference was a significant one, however, they aren’t sure what’s causing a link between sleep habits and nightmares. Among their ideas is the stress hormone cortisol, which peaks in the morning right before we wake up, a time when people are more prone to be in REM, or dream, sleep. If you’re still sleeping at that time, the cortisol rise could trigger vivid dreams or nightmares, the researchers speculate. [ Top 10 Spooky Sleep Disorders ]
3. Men dream about sex
As in their wake hours, men also dream about sex more than women do. And comparing notes in the morning may not be a turn-on for either guys or gals, as women are more likely to have experienced nightmares, suggests doctoral research reported in 2009 by psychologist Jennie Parker of the University of the West of England.
She found women’s dreams/nightmares could be grouped into three categories: fearful dreams (being chased or having their life threatened); dreams involving the loss of a loved one; or confused dreams.
4. You can control your dreams
If you’re interested in lucid dreaming, you may want to take up video gaming. The link? Both represent alternate realities, said Jayne Gackenbach, a psychologist at Grant MacEwan University in Canada.
“If you’re spending hours a day in a virtual reality, if nothing else it’s practice,” Gackenbach told LiveScience in 2010. “Gamers are used to controlling their game environments, so that can translate into dreams.” Her past research has shown that people who frequently play video games are more likely than non-gamers to have lucid dreams where they view themselves from outside their bodies; they were also better able to influence their dream worlds, as if controlling a video-game character.
That level of control may also help gamers turn a bloodcurdling nightmare into a carefree dream, she found in a 2008 study. This ability could help war veterans suffering from post-traumatic stress disorder (PTSD), Gackenbach reasoned.
5. Why we dream
Scientists have long wondered why we dream, with answers ranging from Sigmund Freud’s idea that dreams fulfill our wishes to the speculation that these wistful journeys are just a side effect of rapid-eye-movement (REM) sleep. Turns out, at least part of the reason may be critical thinking, suggests Harvard psychologist Deirdre Barrett who presented her theory in 2010 at the Association for Psychological Science meeting in Boston.
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Her research revealed that our slumbering hours may help us solve puzzles that have plagued us during daylight hours. The visual and often illogical aspects of dreams make them perfect for the out-of-the-box thinking that is necessary to solve some problems, she speculates.
So while dreams may have originally evolved for another purpose, they have likely been refined over time for multiple tasks, including helping the brain reboot and helping us solve problems, she said.
- 5 Mind-Bending Facts About Dreams (mytechnologyworld9.blogspot.com)
- 5 mind-bending facts about dreams (psychieblog.wordpress.com)
- Violent Dreams Can Be A Warning Sign (businessinsider.com)
- 5 mind-bending facts about dreams (purestrange.wordpress.com)
- Sleeper Sell! No Rest for City’s Techies as ‘Lucid Dreaming’ Gets Trendy (betabeat.com)
There has been a lot of work in animals linking both acute and chronic stress to changes in a part of the brain called the prefrontal cortex, which is involved in complex cognitive abilities like holding on to important information for quick recall and use,” says Jamie Hanson, a UW-Madison psychology graduate student. “We have now found similar associations in humans, and found that more exposure to stress is related to more issues with certain kinds of cognitive processes.”
Children who had experienced more intense and lasting stressful events in their lives posted lower scores on tests of what the researchers refer to as spatial working memory. They had more trouble navigating tests of short-term memory such as finding a token in a series of boxes, according to the study, which will be published in the June 6 issue of the Journal of Neuroscience.
Brain scans revealed that the anterior cingulate, a portion of the prefrontal cortex believed to play key roles in spatial working memory, takes up less space in children with greater exposure to very stressful situations.
“These are subtle differences, but differences related to important cognitive abilities” Hanson says.
But they maybe not irreversible differences.
“We’re not trying to argue that stress permanently scars your brain. We don’t know if and how it is that stress affects the brain,” Hanson says. “We only have a snapshot — one MRI scan of each subject — and at this point we don’t understand whether this is just a delay in development or a lasting difference. It could be that, because the brains is very plastic, very able to change, that children who have experienced a great deal of stress catch up in these areas.”
The researchers determined stress levels through interviews with children ages 9 to 14 and their parents. The research team, which included UW-Madison psychology professors Richard Davidson and Seth Pollak and their labs, collected expansive biographies of stressful events from slight to severe.
“Instead of focusing in on one specific type of stress, we tried to look at a range of stressors,” Hanson says. “We wanted to know as much as we could, and then use all this information to later to get an idea of how challenging and chronic and intense each experience was for the child.”
Interestingly, there was little correlation between cumulative life stress and age. That is, children who had several more years of life in which to experience stressful episodes were no more likely than their younger peers to have accumulated a length stress resume. Puberty, on the other hand, typically went hand-in-hand with heavier doses of stress.
The researchers, whose work was funded by the National Institutes of Health, also took note of changes in brain tissue known as white matter and gray matter. In the important brain areas that varied in volume with stress, the white and gray matter volumes were lower in tandem.
White matter, Hanson explained, is like the long-distance wiring of the brain. It connects separated parts of the brain so that they can share information. Gray matter “does the math,” Hanson says. “It takes care of the processing, using the information that gets shared along the white matter connections.”
Gray matter early in development appears to enable flexibility; children can play and excel at many different activities. But as kids age and specialize, gray matter thins. It begins to be “pruned” after puberty, while the amount of white matter grows into adulthood.
“For both gray and white matter, we actually see smaller volumes associated with high stress,” Hanson says. “Those kinds of effects across different kinds of tissue, those are the things we would like to study over longer periods of time. Understanding how these areas change can give you a better picture of whether this is just a delay in development or more lasting.”
More study could also show the researchers how to help children who have experienced an inordinate amount of stress.
“There are groups around the country doing working memory interventions to try to train or retrain people on this particular cognitive ability and improve performance,” Hanson says. “Understanding if and how stress affects these processes could help us know whether there may be similar interventions that could aid children living in stressful conditions, and how this may affect the brain.”
- Stress Alters Kids’ Brains, Study Suggests – msnbc.com (msnbc.msn.com)