Archive for the ‘memory’ Category

Sleeping minds: prepare to be hacked. For the first time, conscious memories have been implanted into the minds of mice while they sleep. The same technique could one day be used to alter memories in people who have undergone traumatic events.

When we sleep, our brain replays the day’s activities. The pattern of brain activity exhibited by mice when they explore a new area during the day, for example, will reappear, speeded up, while the animal sleeps. This is thought to be the brain practising an activity – an essential part of learning. People who miss out on sleep do not learn as well as those who get a good night’s rest, and when the replay process is disrupted in mice, so too is their ability to remember what they learned the previous day.

Karim Benchenane and his colleagues at the Industrial Physics and Chemistry Higher Educational Institution in Paris, France, hijacked this process to create new memories in sleeping mice. The team targeted the rodents’ place cells – neurons that fire in response to being in or thinking about a specific place. These cells are thought to help us form internal maps, and their discoverers won a Nobel prize last year.

Benchenane’s team used electrodes to monitor the activity of mice’s place cells as the animals explored an enclosed arena, and in each mouse they identified a cell that fired only in a certain arena location. Later, when the mice were sleeping, the researchers monitored the animals’ brain activity as they replayed the day’s experiences. A computer recognised when the specific place cell fired; each time it did, a separate electrode would stimulate brain areas associated with reward.

When the mice awoke, they made a beeline for the location represented by the place cell that had been linked to a rewarding feeling in their sleep. A brand new memory – linking a place with reward – had been formed.

It is the first time a conscious memory has been created in animals during sleep. In recent years, researchers have been able to form subconscious associations in sleeping minds – smokers keen to quit can learn to associate cigarettes with the smells of rotten eggs and fish in their sleep, for example.

Previous work suggested that if this kind of subconscious learning had occurred in Benchenane’s mice, they would have explored the arena in a random manner, perhaps stopping at the reward-associated location. But these mice headed straight for the location, suggesting a conscious memory. “The mouse develops a goal-directed behaviour to go towards the place,” says Benchenane. “It proves that it’s not an automatic behaviour. What we create is an association between a particular place and a reward that can be consciously accessed by the mouse.”

“The mouse is remembering enough abstract information to think ‘I want to go to a certain place’, and go there when it wakes up,” says neuroscientist Neil Burgess at University College London. “It’s a bigger breakthrough [than previous studies] because it really does show what the man in the street would call a memory – the ability to bring to mind abstract knowledge which can guide behaviour in a directed way.”

Benchenane doesn’t think the technique can be used to implant many other types of memories, such as skills – at least for the time being. Spatial memories are easier to modify because they are among the best understood.

His team’s findings also provide some of the strongest evidence for the way in which place cells work. It is almost impossible to test whether place cells function as an internal map while animals are awake, says Benchenane, because these animals also use external cues, such as landmarks, to navigate. By specifically targeting place cells while the mouse is asleep, the team were able to directly test theories that specific cells represent specific places.

“Even when those place cells fire in sleep, they still convey spatial information,” says Benchenane. “That provides evidence that when you’ve got activation of place cells during the consolidation of memories in sleep, you’ve got consolidation of the spatial information.”

Benchenane hopes that his technique could be developed to help alter people’s memories, perhaps of traumatic events (see “Now it’s our turn”, below).

Loren Frank at the University of California, San Francisco, agrees. “I think this is a really important step towards helping people with memory impairments or depression,” he says. “It is surprising to me how many neurological and psychiatric illnesses have something to do with memory, including schizophrenia and obsessive compulsive disorder.”

“In principle, you could selectively change brain processing during sleep to soften memories or change their emotional content,” he adds.

Journal reference: Nature Neuroscience, doi:10.1038/nn.3970

http://www.newscientist.com/article/dn27115-new-memories-implanted-in-mice-while-they-sleep.html#.VP_L9uOVquD

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

Everyone knows it’s easier to learn about a topic you’re curious about. Now, a new study reveals what’s going on in the brain during that process, revealing that such curiosity may give a person a memory boost.

When participants in the study were feeling curious, they were better at remembering information even about unrelated topics, and brain scans showed activity in areas linked to reward and memory.

The results, detailed October 2 in the journal Neuron, hint at ways to improve learning and memory in both healthy people and those with neurological disorders, the researchers said.

“Curiosity may put the brain in a state that allows it to learn and retain any kind of information, like a vortex that sucks in what you are motivated to learn, and also everything around it,” Matthias Gruber, a memory researcher at the University of California, Davis, said in a statement. “These findings suggest ways to enhance learning in the classroom and other settings.”

Gruber and his colleagues put people in a magnetic resonance imaging (MRI) scanner and showed them a series of trivia questions, asking them to rate their curiosity about the answers to those questions. Later, the participants were shown selected trivia questions, then a picture of a neutral face during a 14-second delay, followed by the answer. Afterward, the participants were given a surprise memory test of the faces, and then a memory test of the trivia answers.

Not surprisingly, the study researchers found that people remembered more information about the trivia when they were curious about the trivia answers. But unexpectedly, when the participants were curious, they were also better at remembering the faces, an entirely unrelated task. Participants who were curious were also more likley than others to remember both the trivia information and unrelated faces a day later, the researchers found.

The brain scans showed that, compared with when their curiosity wasn’t piqued, when people were curious, they showed more activation of brain circuits in the nucleus accumbens, an area involved in reward. These same circuits, mediated by the neurochemical messenger dopamine, are involved in forms of external motivation, such as food, sex or drug addiction.

Finally, being curious while learning seemed to produce a spike of activity in the hippocampus, an area involved in forming new memories, and strengthened the link between memory and reward brain circuits.

The study’s findings not only highlight the importance of curiosity for learning in healthy people, but could also give insight into neurological conditions. For example, as people age, their dopamine circuits tend to deteriorate, so understanding how curiosity affects these circuits could help scientists develop treatments for patients with memory disorders, the researchers said.

http://www.livescience.com/48121-curiosity-boosts-memory-learning.html

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Most adults struggle to recall events from their first few years of life and now scientists have identified exactly when these childhood memories fade and are lost forever.

A new study into childhood amnesia – the phenomenon where early memories are forgotten – has found that it tends to take affect around the age of seven.

The researchers found that while most three year olds can recall a lot of what happened to them over a year earlier, these memories can persist while they are five and six, but by the time they are over seven these memories decline rapidly.

Most children by the age of eight or nine can only recall 35% of their experiences from under the age of three, according to the new findings.

The psychologists behind the research say this is because at around this age the way we form memories begins to change.

They say that before the age of seven children tend to have an immature form of recall where they do not have a sense of time or place in their memories.

In older children, however, the early events they can recall tend to be more adult like in their content and the way they are formed.

Children also have a far faster rate of forgetting than adults and so the turnover of memories tends to be higher, meaning early memories are less likely to survive.

The findings also help to explain why children can often have vivid memories of events but then have forgotten them just a couple of years later.

Professor Patricia Bauer, a psychologist and associate dean for research at Emory college of Arts and Science who led the study, said: “The paradox of children’s memory competence and adults’ seeming “incompetence” at remembering early childhood events is striking.

“Though forgetting is more rapid in the early childhood years, eventually it slows to adult levels.

“Thus memories that “survived” early childhood have some likelihood of being remembered later in life.”

Professor Bauer and her colleagues studied 83 children over several years for the research, which is published in the scientific journal Memory.

The youngsters first visited the laboratory at the age of three years old and discussed six unique events from their past, such as family outings, camping holidays, trips to the zoo, first day of school and birthdays.

The children then returned for a second session at the ages between five years old and nine years old to discuss the same events and were asked to recall details they had previously remembered.

The researchers found that between the ages of five and seven, the amount of the memories the children could recall remained between 63-72 per cent.

However, the amount of information the children who were 8 and nine years old dropped dramatically to 35 and 36 per cent.

When the researchers looked closely at the kind of details the children were and were not able to remember, they found marked age differences.

The memories of the younger children tended to lack autobiographical narrative such as place and time. Their memories also had less narrative, which the researchers believe may lead to a process known as “retrieval induced forgetting” – where the action of remembering causes other information to be forgotten.

As they children got older, however, the memories they recalled from early childhood tended to have these features.

Professor Bauer said: “The fact that the younger children had less-complete narratives relative to the older children, likely has consequences for the continued accessibility of early memories beyond the first decade of life.

“We may anticipate that memories that survive into the ninth or tenth year of life, when narrative skills are more developed, would continue to be accessible over time.”

http://www.telegraph.co.uk/science/science-news/10564312/Scientists-pinpoint-age-when-childhood-memories-fade.html

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On Feb. 21, Alexandra Wolff ate steak, mashed potatoes and broccoli for dinner. Later that night, sitting in her room, she spent 20 minutes scanning pictures in InStyle magazine.

She remembers those things, just as she remembers that on Aug. 2 she stopped at Target and bought Raisin Bran; and on April 17 she wore a white button-down shirt; and on Oct. 2 she went to TGI Fridays and spoke to the hostess, who was wearing black leather flats with small bows on them.

Alexandra Wolff has what’s known as highly superior autobiographical memory. She is one of only 55 people in the U.S. who have been identified with this ability. All of these people can remember details about their lives that the rest of us couldn’t hope to remember: the strangers they pass on the street, the first thing they saw when they woke up seven months ago.

And though it’s not clear why the brains of people with HSAM can do what they do, what is clear is that this ability gives them an access to the past that’s profoundly different from you and me.

If you think of 2013, probably only a handful of memories stand out. The day-by-day is a blur.

We forget most of our lives.

But Alexandra says that remembering even an inconsequential trip to Target is an almost physical experience for her. She says she sees what she saw that day, hears what she heard, and emotionally feels what she felt at the time.

“Right down to getting sick to my stomach or getting a headache,” she says. “It’s almost like time travel.”

But being unable to forget can affect your relationship to the present, people with this form of memory say.

Alexandra is 22 and lives with her mother in a long brick ranch house in southern Maryland. She has dark hair and beautifully balanced features, but hasn’t really dated and seems to have few of the preoccupations of most 22-year-olds. She blames her memory for this, saying it separates her from other people her age because they can’t understand why she’s so focused on things that have already happened.

Alexandra often feels frustrated with her preoccupation with the past. “It seems like you hold onto everything, and it seems like you’re just stuck in the past all the time,” she says.

It really bothers her. For one, Alexandra says, in her life there are no fresh days, no clean slates without association. Every morning when she wakes up, details of that date from years before are scrolling through her mind, details that can profoundly affect the new day she’s in.

For example, the day before we spoke was a day when years ago in middle school a boy bullied her in one of her classes.

“I didn’t mention it to anyone,” she says, “but I mean, still in the back of my mind I kept thinking and thinking about it. It knocked some of my confidence down.”

Because the past is so viscerally right there, so available, she finds that when the present gets overwhelming, it’s hard not to retreat to the past.

Even though she’s only 22, she says she spends huge amounts of time in her room with her eyes closed, reliving the past in her mind, particularly this one day a decade ago.

It was July 8, 2004. She spent that day in a bathing suit by a pool laughing and playing with her 10-year-old cousin. They ate macaroni and cheese, and swam. It was an easy, innocent time.

She says she probably takes herself through that day in her mind four times a week. Over the past couple of years, she estimates, she’s probably spent close to 2,000 hours reliving that one day.

“I mean, I definitely say it’s a huge temptation. I could, if I didn’t have stuff to do all day, I could probably live in the past 24/7.”
Scientists think there’s a reason why we forget.

“It has long been believed by research scientists that forgetting is adaptive,” says James McGaugh, the University of California, Irvine neurobiologist who first documented highly superior autobiographical memory.

McGaugh discovered HSAM by accident. He got an email out of the blue from a woman named Jill Price who said she had a serious memory problem: She couldn’t seem to forget anything, and like Alexandra, this bothered her.

“The emotions evoked by remembering bad things troubled her,” McGaugh says.

And so McGaugh started studying first Price and then other people with this kind of memory. He found ultimately that there are differences in the brains of people with HSAM, though it’s not clear whether the differences are the cause or the consequence of this ability.

But it is clear that it’s specifically this issue of forgetting that’s different. If you were asked to recall what happened to you earlier this morning, you’d remember roughly the same amount as someone like Alexandra. But if asked about this morning three months from now, for you it would probably be gone, while for her it’s as fresh as it is for you today.

“So it’s not that they’re superior learners,” McGaugh says, “it’s that they are very poor at forgetting.”
The emotional effects of not being able to forget aren’t clear, says McGaugh. No one, including McGaugh, has studied it. His sense is that there is variation in the group of 55.

“The effects of having this ability depends on the kind of experiences people have had in the past as well as their present circumstances,” he says.

But Bill Brown, another person with HSAM, says that he’s been in touch with most of the people in the group, and that everyone he has spoken to has struggled with depression. He says that very few of them have been able to maintain a long-term marriage — the rumor is only 2 out of the 55.
Brown himself, though a pretty jolly guy, recently separated from his wife.

And talking to him, you do get the sense that the difference in his memory has led to misunderstandings in his relationships.

“Just because I remember something that you did wrong doesn’t mean that I still hold it against you,” he says. “But it’s taken me a long while to realize that folks without my ability probably don’t understand that distinction. Because after all, if you’re bringing it up, the logic from the other side would be: You must still hold it against me.”

This is not, in fact, the case, he says. “It has more to do with wanting you to be honest in your dealings.”

What he eventually realized was that most of the people he talks to are being as honest as they know how to be. “They just don’t necessarily remember.”
Brown says it’s easier for him now, because over time he’s learned how to manage the memories, not to focus on the bad stuff, and instead use his memory to entertain himself.

“But you know,” he says, “life’s rough, and there’s so much bad that’s kinda there.”

Sometimes, he says, he thinks it might be nice to forget.

http://www.npr.org/blogs/health/2013/12/18/255285479/when-memories-never-fade-the-past-can-poison-the-present

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It’s never too early to start protecting your brain power, a new study suggests.

Reading, writing and participating in other brain-stimulating activities at any age may protect your memory later in life, according to the research. The study, which tracked 294 individuals, is published online in the July 3 issue of Neurology.

“Our study suggests that exercising your brain by taking part in activities such as these across a person’s lifetime, from childhood through old age, is important for brain health in old age,” said the study’s lead author, Robert Wilson.

After adjusting for signs of brain disease, higher levels of cognitive activity across the life span were associated with slower cognitive decline, the study found. Mental activity explained about 14% of the differences between people in how much their memory and thinking skills declined.

The finding supports the hypothesis of cognitive reserve, which describes the brain’s ability to cope with disease or damage. According to the hypothesis, mental activity helps delay the cognitive consequences of disease.

Neuroimaging research suggests that cognitive activity can lead to changes in brain structure and function that may enhance cognitive reserve.

“An intellectually stimulating lifestyle helps to contribute to cognitive reserve and allows you to tolerate these age-related brain pathologies better than someone who has had a less cognitively active lifestyle,” says Wilson, a neuropsychologist at Rush University Medical Center in Chicago.

He recommends that people have cognitively stimulating hobbies that they enjoy, such as photography and quilting.

Intellectually stimulating activities involve processing and using information. Examples are reading a book and then predicting what will happen next, as well as watching a movie and then comparing it with other films, says Judy Willis, a neurologist based in Santa Barbara, Calif.

Willis says doing a variety of cognitive activities appears to be more protective of the cognitive reserve than focusing on one thing, even something like playing chess. “More research is needed to look at how much time should be devoted to an activity or learning a skill and how often it should be revisited,” she adds.

Willis, who was not involved in the study, agrees that the activities should be motivated by pleasure. “Forcing yourself to do something takes a lot of mental effort,” she adds. “If you try something and don’t like it, try something else.”

http://www.usatoday.com/story/news/nation/2013/07/03/brain-aging-activities/2461655/

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William Gibson’s popular science fiction tale “Johnny Mnemonic” foresaw sensitive information being carried by microchips in the brain by 2021. A team of American neuroscientists could be making this fantasy world a reality. Their motivation is different but the outcome would be somewhat similar. Hailed as one of 2013’s top ten technological breakthroughs by MIT, the work by the University of Southern California, North Carolina’s Wake Forest University and other partners has actually spanned a decade.

But the U.S.-wide team now thinks that it will see a memory device being implanted in a small number of human volunteers within two years and available to patients in five to 10 years. They can’t quite contain their excitement. “I never thought I’d see this in my lifetime,” said Ted Berger, professor of biomedical engineering at the University of Southern California in Los Angeles. “I might not benefit from it myself but my kids will.”

Rob Hampson, associate professor of physiology and pharmacology at Wake Forest University, agrees. “We keep pushing forward, every time I put an estimate on it, it gets shorter and shorter.”

The scientists — who bring varied skills to the table, including mathematical modeling and psychiatry — believe they have cracked how long-term memories are made, stored and retrieved and how to replicate this process in brains that are damaged, particularly by stroke or localized injury.

Berger said they record a memory being made, in an undamaged area of the brain, then use that data to predict what a damaged area “downstream” should be doing. Electrodes are then used to stimulate the damaged area to replicate the action of the undamaged cells.

They concentrate on the hippocampus — part of the cerebral cortex which sits deep in the brain — where short-term memories become long-term ones. Berger has looked at how electrical signals travel through neurons there to form those long-term memories and has used his expertise in mathematical modeling to mimic these movements using electronics.

Hampson, whose university has done much of the animal studies, adds: “We support and reinforce the signal in the hippocampus but we are moving forward with the idea that if you can study enough of the inputs and outputs to replace the function of the hippocampus, you can bypass the hippocampus.”

The team’s experiments on rats and monkeys have shown that certain brain functions can be replaced with signals via electrodes. You would think that the work of then creating an implant for people and getting such a thing approved would be a Herculean task, but think again.

For 15 years, people have been having brain implants to provide deep brain stimulation to treat epilepsy and Parkinson’s disease — a reported 80,000 people have now had such devices placed in their brains. So many of the hurdles have already been overcome — particularly the “yuck factor” and the fear factor.

“It’s now commonly accepted that humans will have electrodes put in them — it’s done for epilepsy, deep brain stimulation, (that has made it) easier for investigative research, it’s much more acceptable now than five to 10 years ago,” Hampson says.

Much of the work that remains now is in shrinking down the electronics.

“Right now it’s not a device, it’s a fair amount of equipment,”Hampson says. “We’re probably looking at devices in the five to 10 year range for human patients.”

The ultimate goal in memory research would be to treat Alzheimer’s Disease but unlike in stroke or localized brain injury, Alzheimer’s tends to affect many parts of the brain, especially in its later stages, making these implants a less likely option any time soon.

Berger foresees a future, however, where drugs and implants could be used together to treat early dementia. Drugs could be used to enhance the action of cells that surround the most damaged areas, and the team’s memory implant could be used to replace a lot of the lost cells in the center of the damaged area. “I think the best strategy is going to involve both drugs and devices,” he says.

Unfortunately, the team found that its method can’t help patients with advanced dementia.

“When looking at a patient with mild memory loss, there’s probably enough residual signal to work with, but not when there’s significant memory loss,” Hampson said.

Constantine Lyketsos, professor of psychiatry and behavioral sciences at John Hopkins Medicine in Baltimore which is trialing a deep brain stimulator implant for Alzheimer’s patients was a little skeptical of the other team’s claims.

“The brain has a lot of redundancy, it can function pretty well if loses one or two parts. But memory involves circuits diffusely dispersed throughout the brain so it’s hard to envision.” However, he added that it was more likely to be successful in helping victims of stroke or localized brain injury as indeed its makers are aiming to do.

The UK’s Alzheimer’s Society is cautiously optimistic.

“Finding ways to combat symptoms caused by changes in the brain is an ongoing battle for researchers. An implant like this one is an interesting avenue to explore,” said Doug Brown, director of research and development.

Hampson says the team’s breakthrough is “like the difference between a cane, to help you walk, and a prosthetic limb — it’s two different approaches.”

It will still take time for many people to accept their findings and their claims, he says, but they don’t expect to have a shortage of volunteers stepping forward to try their implant — the project is partly funded by the U.S. military which is looking for help with battlefield injuries.

There are U.S. soldiers coming back from operations with brain trauma and a neurologist at DARPA (the Defense Advanced Research Projects Agency) is asking “what can you do for my boys?” Hampson says.

“That’s what it’s all about.”

http://www.cnn.com/2013/05/07/tech/brain-memory-implants-humans/index.html?iref=allsearch

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The flip of a single molecular switch helps create the mature neuronal connections that allow the brain to bridge the gap between adolescent impressionability and adult stability. Now Yale School of Medicine researchers have reversed the process, recreating a youthful brain that facilitated both learning and healing in the adult mouse.

Scientists have long known that the young and old brains are very different. Adolescent brains are more malleable or plastic, which allows them to learn languages more quickly than adults and speeds recovery from brain injuries. The comparative rigidity of the adult brain results in part from the function of a single gene that slows the rapid change in synaptic connections between neurons.

By monitoring the synapses in living mice over weeks and months, Yale researchers have identified the key genetic switch for brain maturation a study released March 6 in the journal Neuron. The Nogo Receptor 1 gene is required to suppress high levels of plasticity in the adolescent brain and create the relatively quiescent levels of plasticity in adulthood. In mice without this gene, juvenile levels of brain plasticity persist throughout adulthood. When researchers blocked the function of this gene in old mice, they reset the old brain to adolescent levels of plasticity.

“These are the molecules the brain needs for the transition from adolescence to adulthood,” said Dr. Stephen Strittmatter. Vincent Coates Professor of Neurology, Professor of Neurobiology and senior author of the paper. “It suggests we can turn back the clock in the adult brain and recover from trauma the way kids recover.”

Rehabilitation after brain injuries like strokes requires that patients re-learn tasks such as moving a hand. Researchers found that adult mice lacking Nogo Receptor recovered from injury as quickly as adolescent mice and mastered new, complex motor tasks more quickly than adults with the receptor.

“This raises the potential that manipulating Nogo Receptor in humans might accelerate and magnify rehabilitation after brain injuries like strokes,” said Feras Akbik, Yale doctoral student who is first author of the study.

Researchers also showed that Nogo Receptor slows loss of memories. Mice without Nogo receptor lost stressful memories more quickly, suggesting that manipulating the receptor could help treat post-traumatic stress disorder.

“We know a lot about the early development of the brain,” Strittmatter said, “But we know amazingly little about what happens in the brain during late adolescence.”

Other Yale authors are: Sarah M. Bhagat, Pujan R. Patel and William B.J. Cafferty

The study was funded by the National Institutes of Health. Strittmatter is scientific founder of Axerion Therapeutics, which is investigating applications of Nogo research to repair spinal cord damage.

http://news.yale.edu/2013/03/06/flip-single-molecular-switch-makes-old-brain-young