Neuroscience

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Posts tagged memory

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The role of lactate in boosting memory

Everyone knows that neurons are the key to how the brain operates. But it turns out they aren’t the only stars in the show; neighboring cells called astrocytes are quickly gaining increasing respect for the critical role they play in memory and learning. EPFL scientists have recently outlined the molecular mechanics of this process in an article published in Proceedings of the National Academy of Sciences (PNAS). Lactate produced by the star-shaped astrocytes accelerates the memorization process. This result, surprising until very recently, opens up new possibilities for treating cognitive and memory disorders, as well as psychiatric conditions such as depression.

Our brains are greedy, gobbling up as much as 25% of our daily energy consumption. Neurons and astrocytes thrive on glucose. Neurons use it to protect themselves from the buildup of toxic products resulting from their activity. Astrocytes, which are glial cells (as opposed to neurons), manufacture lactate; this was long thought to be a byproduct of glucose metabolism, and then as a simple energy source for neurons.

In 2011, research published in the journal Cell by EPFL’s Laboratory of Neuroenergetics and Cellular Dynamics in collaboration with a U.S. team unveiled the critical role of lactate. “In vivo, when the transfer of lactate from astrocytes to neurons is blocked, we found that the memorization process was also blocked,” explains EPFL professor Pierre Magistretti, head of the lab. “We thus knew that it was an essential fuel for that process.”

Focusing their attention on the molecular mechanism, the scientists discovered that lactate provides more than just energy. It acts as a moderator of one type of glutamate receptor (NMDA receptors), the nervous system’s primary neurotransmitter. This glutamate receptor is involved in the memorization process, and the research demonstrates that lactate gives them what amounts to a turbo-boost. “Glutamate lets you drive in first gear; with lactate, you can shift into fourth and travel at 100 km/h,” says Magistretti.

Palliating cognitive deficits
The scientists did their initial research in vitro. They exposed mice neurons to various substances and measured their effect on the expression of genes involved in memory. Glucose and pyruvate (another glucose derivative) didn’t have any effect. A lactate supplement, on the other hand, triggered the expression of four genes involved in cerebral plasticity that are essential to memorization.

They followed this work with in vivo studies, which confirmed their results. They administered lactate into the brains of living mice, and then extracted the tissues and measured gene expression. Once again, the expression of genes involved in cerebral plasticity increased significantly.

Could we take lactate supplements and develop encyclopedic memory? Magistretti’s lab has just received a grant to study the effects of artificial lactate supplementation. “We have identified a series of molecules that can make astrocytes produce more lactate. Now the idea is to see in vivo if we can mitigate cognitive deficits and memory disorders.” In addition, since conditions such as depression are often accompanied by cognitive problems, “lactate could also have an antidepressant effect,” says Magistretti, who also conducts research at the National Center for Competence in Research Synapsy, dedicated to the understanding of the synaptic basis of psychiatric disease.

(Source: actu.epfl.ch)

Filed under astrocytes memory glucose NMDA receptors lactate synaptic plasticity neuroscience science

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New research sheds light on how children’s brains memorize facts


As children learn basic arithmetic, they gradually switch from solving problems by counting on their fingers to pulling facts from memory. The shift comes more easily for some kids than for others, but no one knows why.
Now, new brain-imaging research gives the first evidence drawn from a longitudinal study to explain how the brain reorganizes itself as children learn math facts. A precisely orchestrated group of brain changes, many involving the memory center known as the hippocampus, are essential to the transformation, according to a study from the Stanford University School of Medicine.
The results, published online Aug. 17 in Nature Neuroscience, explain brain reorganization during normal development of cognitive skills and will serve as a point of comparison for future studies of what goes awry in the brains of children with learning disabilities.
“We wanted to understand how children acquire new knowledge, and determine why some children learn to retrieve facts from memory better than others,” said Vinod Menon, PhD, the Rachael L. and Walter F. Nichols, MD, Professor and  professor of psychiatry and behavioral sciences, and the senior author of the study. “This work provides insight into the dynamic changes that occur over the course of cognitive development in each child.”




The study also adds to prior research into the differences between how children’s and adults’ brains solve math problems. Children use certain brain regions, including the hippocampus and the prefrontal cortex, very differently from adults when the two groups are solving the same types of math problems, the study showed.
“It was surprising to us that the hippocampal and prefrontal contributions to memory-based problem-solving during childhood don’t look anything like what we would have expected for the adult brain,” said postdoctoral scholar Shaozheng Qin, PhD, who is the paper’s lead author.
Charting the shifting strategy
In the study, 28 children solved simple math problems while receiving two functional magnetic resonance imaging brain scans; the scans were done about 1.2 years apart. The researchers also scanned 20 adolescents and 20 adults at a single time point. At the start of the study, the children were ages 7-9. The adolescents were 14-17 and the adults were 19-22. The participants had normal IQs. Because the study examined normal math learning, potential participants with math-related learning disabilities and attention deficit hyperactivity disorder were excluded. The children and adolescents were studying math in school; the researchers did not provide any math instruction.
During the study, as the children aged from an average of 8.2 to 9.4 years, they became faster and more accurate at solving math problems, and relied more on retrieving math facts from memory and less on counting. As these shifts in strategy took place, the researchers saw several changes in the children’s brains. The hippocampus, a region with many roles in shaping new memories, was activated more in children’s brains after one year. Regions involved in counting, including parts of the prefrontal and parietal cortex, were activated less.


The scientists also saw changes in the degree to which the hippocampus was connected to other parts of children’s brains, with several parts of the prefrontal, anterior temporal cortex and parietal cortex more strongly connected to the hippocampus after one year. Crucially, the stronger these connections, the greater was each individual child’s ability to retrieve math facts from memory, a finding that suggests a starting point for future studies of math-learning disabilities.
Although children were using their hippocampus more after a year, adolescents and adults made minimal use of their hippocampus while solving math problems. Instead, they pulled math facts from well-developed information stores in the neocortex.
Memory scaffold
“What this means is that the hippocampus is providing a scaffold for learning and consolidating facts into long-term memory in children,” said Menon, who is also the Rachel L. and Walter F. Nichols, MD, Professor at the medical school. Children’s brains are building a schema for mathematical knowledge. The hippocampus helps support other parts of the brain as adultlike neural connections for solving math problems are being constructed. “In adults this scaffold is not needed because memory for math facts has most likely been consolidated into the neocortex,” he said. Interestingly, the research also showed that, although the adult hippocampus is not as strongly engaged as in children, it seems to keep a backup copy of the math information that adults usually draw from the neocortex.
The researchers compared the level of variation in patterns of brain activity as children, adolescents and adults correctly solved math problems. The brain’s activity patterns were more stable in adolescents and adults than in children, suggesting that as the brain gets better at solving math problems its activity becomes more consistent.
The next step, Menon said, is to compare the new findings about normal math learning to what happens in children with math-learning disabilities.
“In children with math-learning disabilities, we know that the ability to retrieve facts fluently is a basic problem, and remains a bottleneck for them in high school and college,” he said. “Is it that the hippocampus can’t provide a reliable scaffold to build good representations of math facts in other parts of the brain during the early stages of learning, and so the child continues to use inefficient strategies to solve math problems? We want to test this.”

New research sheds light on how children’s brains memorize facts

As children learn basic arithmetic, they gradually switch from solving problems by counting on their fingers to pulling facts from memory. The shift comes more easily for some kids than for others, but no one knows why.

Now, new brain-imaging research gives the first evidence drawn from a longitudinal study to explain how the brain reorganizes itself as children learn math facts. A precisely orchestrated group of brain changes, many involving the memory center known as the hippocampus, are essential to the transformation, according to a study from the Stanford University School of Medicine.

The results, published online Aug. 17 in Nature Neuroscience, explain brain reorganization during normal development of cognitive skills and will serve as a point of comparison for future studies of what goes awry in the brains of children with learning disabilities.

“We wanted to understand how children acquire new knowledge, and determine why some children learn to retrieve facts from memory better than others,” said Vinod Menon, PhD, the Rachael L. and Walter F. Nichols, MD, Professor and  professor of psychiatry and behavioral sciences, and the senior author of the study. “This work provides insight into the dynamic changes that occur over the course of cognitive development in each child.”

The study also adds to prior research into the differences between how children’s and adults’ brains solve math problems. Children use certain brain regions, including the hippocampus and the prefrontal cortex, very differently from adults when the two groups are solving the same types of math problems, the study showed.

“It was surprising to us that the hippocampal and prefrontal contributions to memory-based problem-solving during childhood don’t look anything like what we would have expected for the adult brain,” said postdoctoral scholar Shaozheng Qin, PhD, who is the paper’s lead author.

Charting the shifting strategy

In the study, 28 children solved simple math problems while receiving two functional magnetic resonance imaging brain scans; the scans were done about 1.2 years apart. The researchers also scanned 20 adolescents and 20 adults at a single time point. At the start of the study, the children were ages 7-9. The adolescents were 14-17 and the adults were 19-22. The participants had normal IQs. Because the study examined normal math learning, potential participants with math-related learning disabilities and attention deficit hyperactivity disorder were excluded. The children and adolescents were studying math in school; the researchers did not provide any math instruction.

During the study, as the children aged from an average of 8.2 to 9.4 years, they became faster and more accurate at solving math problems, and relied more on retrieving math facts from memory and less on counting. As these shifts in strategy took place, the researchers saw several changes in the children’s brains. The hippocampus, a region with many roles in shaping new memories, was activated more in children’s brains after one year. Regions involved in counting, including parts of the prefrontal and parietal cortex, were activated less.

The scientists also saw changes in the degree to which the hippocampus was connected to other parts of children’s brains, with several parts of the prefrontal, anterior temporal cortex and parietal cortex more strongly connected to the hippocampus after one year. Crucially, the stronger these connections, the greater was each individual child’s ability to retrieve math facts from memory, a finding that suggests a starting point for future studies of math-learning disabilities.

Although children were using their hippocampus more after a year, adolescents and adults made minimal use of their hippocampus while solving math problems. Instead, they pulled math facts from well-developed information stores in the neocortex.

Memory scaffold

“What this means is that the hippocampus is providing a scaffold for learning and consolidating facts into long-term memory in children,” said Menon, who is also the Rachel L. and Walter F. Nichols, MD, Professor at the medical school. Children’s brains are building a schema for mathematical knowledge. The hippocampus helps support other parts of the brain as adultlike neural connections for solving math problems are being constructed. “In adults this scaffold is not needed because memory for math facts has most likely been consolidated into the neocortex,” he said. Interestingly, the research also showed that, although the adult hippocampus is not as strongly engaged as in children, it seems to keep a backup copy of the math information that adults usually draw from the neocortex.

The researchers compared the level of variation in patterns of brain activity as children, adolescents and adults correctly solved math problems. The brain’s activity patterns were more stable in adolescents and adults than in children, suggesting that as the brain gets better at solving math problems its activity becomes more consistent.

The next step, Menon said, is to compare the new findings about normal math learning to what happens in children with math-learning disabilities.

“In children with math-learning disabilities, we know that the ability to retrieve facts fluently is a basic problem, and remains a bottleneck for them in high school and college,” he said. “Is it that the hippocampus can’t provide a reliable scaffold to build good representations of math facts in other parts of the brain during the early stages of learning, and so the child continues to use inefficient strategies to solve math problems? We want to test this.”

Filed under learning hippocampus memory neuroimaging child development cognitive development mathematics neuroscience science

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Stroke researchers link ability to self administer medication after stroke with memory loss

Kessler stroke researchers and colleagues have identified an association between over-optimistic estimation of one’s own ability to take medications accurately, and memory loss among stroke survivors. Results indicate that assessing patients for their ability to estimate medication skills accurately may predict memory disorder. The article, “Stroke survivors over-estimate their medication self-administration ability (MSA), predicting memory loss,” was epublished ahead of print on May 28 by Brain Injury. The authors are AM Barrett, MD, and J Masmela of Kessler Foundation, Elizabeth E Galletta of Hunter College, Jun Zhang of St. Charles Hospital, Port Jefferson, NY, and Uri Adler, MD, of Kessler Institute for Rehabilitation.

image

Researchers compared 24 stroke survivors with 17 controls, using the Hopkins Medication Schedule to assess MSA, the Geriatric Depression Scale to assess mood, and the Hopkins Verbal Test and Mini-Mental State Examination to assess memory. Results showed that stroke survivors over-estimated their MSA in comparison to controls. Over-estimation of MSA correlated strongly with verbal memory deficit.

Strategies that enhance adherence to medication are a public health priority. “Few studies, however, have looked at cognitive factors that may interfere with MSA,” commented Dr. Barrett. “While some stroke survivors have obvious cognitive deficits, many people are not aware that stroke survivors can be intelligent and high functioning, but still have trouble with thinking that can cause errors in medication self-management. These individuals may not realize their own deficits, a condition called cognitive anosognosia. Screening stroke survivors for MSA may be a useful approach to identifying memory deficits that hinder rehabilitation and community participation and contribute to poor outcomes.”

Larger studies of left and right stroke survivors need to be conducted in the community and rehabilitation settings in order to determine the underlying mechanisms for both over-estimation and under-estimation of self-performance.

(Source: kesslerfoundation.org)

Filed under stroke rehabilitation memory anosognosia neuroscience science

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Memories of Errors Foster Faster Learning
Using a deceptively simple set of experiments, researchers at Johns Hopkins have learned why people learn an identical or similar task faster the second, third and subsequent time around. The reason: They are aided not only by memories of how to perform the task, but also by memories of the errors made the first time.
“In learning a new motor task, there appear to be two processes happening at once,” says Reza Shadmehr, Ph.D., a professor in the Department of Biomedical Engineering at the Johns Hopkins University School of Medicine. “One is the learning of the motor commands in the task, and the other is critiquing the learning, much the way a ‘coach’ behaves. Learning the next similar task goes faster, because the coach knows which errors are most worthy of attention. In effect, this second process leaves a memory of the errors that were experienced during the training, so the re-experience of those errors makes the learning go faster.”
Shadmehr says scientists who study motor control — how the brain pilots body movement — have long known that as people perform a task, like opening a door, their brains note small differences between how they expected the door to move and how it actually moved, and they use this information to perform the task more smoothly next time. Those small differences are scientifically termed “prediction errors,” and the process of learning from them is largely unconscious.
The surprise finding in the current study, described in Science Express on Aug. 14, is that not only do such errors train the brain to better perform a specific task, but they also teach it how to learn faster from errors, even when those errors are encountered in a completely different task. In this way, the brain can generalize from one task to another by keeping a memory of the errors.
To study errors and learning, Shadmehr’s team put volunteers in front of a joystick that was under a screen. Volunteers couldn’t see the joystick, but it was represented on the screen as a blue dot. A target was represented by a red dot, and as volunteers moved the joystick toward it, the blue dot could be programmed to move slightly off-kilter from where they pointed it, creating an error. Participants then adjusted their movement to compensate for the off-kilter movement and, after a few more trials, smoothly guided the joystick to its target.
In the study, the movement of the blue dot was rotated to the left or the right by larger or smaller amounts until it was a full 30 degrees off from the joystick’s movement. The research team found that volunteers responded more quickly to smaller errors that pushed them consistently in one direction and less to larger errors and those that went in the opposite direction of other feedback. “They learned to give the frequent errors more weight as learning cues, while discounting those that seemed like flukes,” says David Herzfeld, a graduate student in Shadmehr’s laboratory who led the study.
The results also have given Shadmehr a new perspective on his after-work tennis hobby. “I’m much better in my second five minutes of playing tennis than in my first five minutes, and I always assumed that was because my muscles had warmed up,” he says. “But now I wonder if warming up is really a chance for our brains to re-experience error.”
“This study represents a significant step toward understanding how we learn a motor skill,” says Daofen Chen, Ph.D., a program director at the National Institute of Neurological Disorders and Stroke. “The results may improve movement rehabilitation strategies for the many who have suffered strokes and other neuromotor injuries.”
The next step in the research, Shadmehr says, will be to find out which part of the brain is responsible for the “coaching” job of assigning weight to different types of error.

Memories of Errors Foster Faster Learning

Using a deceptively simple set of experiments, researchers at Johns Hopkins have learned why people learn an identical or similar task faster the second, third and subsequent time around. The reason: They are aided not only by memories of how to perform the task, but also by memories of the errors made the first time.

“In learning a new motor task, there appear to be two processes happening at once,” says Reza Shadmehr, Ph.D., a professor in the Department of Biomedical Engineering at the Johns Hopkins University School of Medicine. “One is the learning of the motor commands in the task, and the other is critiquing the learning, much the way a ‘coach’ behaves. Learning the next similar task goes faster, because the coach knows which errors are most worthy of attention. In effect, this second process leaves a memory of the errors that were experienced during the training, so the re-experience of those errors makes the learning go faster.”

Shadmehr says scientists who study motor control — how the brain pilots body movement — have long known that as people perform a task, like opening a door, their brains note small differences between how they expected the door to move and how it actually moved, and they use this information to perform the task more smoothly next time. Those small differences are scientifically termed “prediction errors,” and the process of learning from them is largely unconscious.

The surprise finding in the current study, described in Science Express on Aug. 14, is that not only do such errors train the brain to better perform a specific task, but they also teach it how to learn faster from errors, even when those errors are encountered in a completely different task. In this way, the brain can generalize from one task to another by keeping a memory of the errors.

To study errors and learning, Shadmehr’s team put volunteers in front of a joystick that was under a screen. Volunteers couldn’t see the joystick, but it was represented on the screen as a blue dot. A target was represented by a red dot, and as volunteers moved the joystick toward it, the blue dot could be programmed to move slightly off-kilter from where they pointed it, creating an error. Participants then adjusted their movement to compensate for the off-kilter movement and, after a few more trials, smoothly guided the joystick to its target.

In the study, the movement of the blue dot was rotated to the left or the right by larger or smaller amounts until it was a full 30 degrees off from the joystick’s movement. The research team found that volunteers responded more quickly to smaller errors that pushed them consistently in one direction and less to larger errors and those that went in the opposite direction of other feedback. “They learned to give the frequent errors more weight as learning cues, while discounting those that seemed like flukes,” says David Herzfeld, a graduate student in Shadmehr’s laboratory who led the study.

The results also have given Shadmehr a new perspective on his after-work tennis hobby. “I’m much better in my second five minutes of playing tennis than in my first five minutes, and I always assumed that was because my muscles had warmed up,” he says. “But now I wonder if warming up is really a chance for our brains to re-experience error.”

“This study represents a significant step toward understanding how we learn a motor skill,” says Daofen Chen, Ph.D., a program director at the National Institute of Neurological Disorders and Stroke. “The results may improve movement rehabilitation strategies for the many who have suffered strokes and other neuromotor injuries.”

The next step in the research, Shadmehr says, will be to find out which part of the brain is responsible for the “coaching” job of assigning weight to different types of error.

Filed under motor learning motor control memory neuroscience science

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Passengers who survived terrifying Air Transat flight in 2001, help psychologists uncover new clues about post-traumatic stress vulnerability

An extraordinary opportunity to study memory and post-traumatic stress disorder (PTSD) in a group of Air Transat passengers who experienced 30 minutes of unimaginable terror over the Atlantic Ocean in 2001 has resulted in the discovery of a potential risk factor that may help predict who is most vulnerable to PTSD.

The study, led by researchers at Baycrest Health Sciences, is published online this week in the journal Clinical Psychological Science – ahead of print publication. It is the first to involve detailed interviews and psychological testing in individuals exposed to the same life-threatening traumatic event. By necessity, other trauma studies involve heterogeneous events as experienced in different situations.

This opportunity was enhanced by the fact that one of the researchers, Dr. Margaret McKinnon, was a passenger on the plane. Heading off on her honeymoon in late August 2001, Dr. McKinnon’s flight departed Toronto for Lisbon, Portugal with 306 passengers and crew on board. Mid way over the Atlantic Ocean, the plane suddenly ran out of fuel. Everyone onboard was instructed to prepare for an ocean ditching, which included a countdown to impact, loss of on-board lighting and cabin de-pressurization. About 25 minutes into the emergency, the pilot located a small island military base in the Azores and glided the aircraft to a rough landing with no loss of life and few injuries.

“Imagine your worst nightmare – that’s what it was like,” said Dr. McKinnon, who initiated the study as a postdoctoral fellow at Baycrest’s Rotman Research Institute. She is now a clinician-scientist at St. Joseph’s Healthcare Hamilton and Associate Co-Chair of Research in the Department of Psychiatry and Behavioural Neurosciences at McMaster University in Hamilton.

“This wasn’t just a close call where your life flashes before your eyes in a split second and then everything is okay,” she said. The sickening feeling of “I’m going to die” lasted an excruciating 30 minutes as the plane’s systems shut down.

Following this incident, Dr. McKinnon and her colleagues at Baycrest – including Dr. Daniela Palombo (now a postdoctoral researcher at VA Boston Healthcare System and Boston University School of Medicine) and Dr. Brian Levine (senior scientist at Baycrest’s Rotman Research Institute and the University of Toronto) – recruited 15 passengers to participate in the Baycrest study. Using their knowledge of the moment-to-moment unfolding of events in this disaster, the researchers were able to probe both the quality and accuracy of passengers’ memories for the AT emergency in great detail along with two other events (Sept. 11, 2001 and a neutral event from the same time period) – and relate their findings to the presence or absence of PTSD in those passengers.

Not all passengers on Flight 236 went on to develop PTSD despite experiencing the same “single blow” traumatic event with the threat of imminent death.

The study produced two key findings. First, the Flight 236 passengers showed tremendously enhanced vivid memories of the plane emergency. Although the Baycrest team was not surprised by this, other research has suggested that memory for traumatic events is impoverished. Second, neither the vividness nor accuracy of memory related to who developed PTSD, but those with PTSD recalled a higher number of details external to the main event (i.e. details that were not specific in time, or were repetitions or editorial statements) compared to passengers who did not have PTSD and to healthy controls. This pattern was observed across all events tested, not just the traumatic event, suggesting that it is not just memory for the trauma itself that is related to PTSD, but rather how a person processes memory for events in general.

“What our findings show is that it is not what happened but to whom it happened that may determine subsequent onset of PTSD,” said Dr. Levine, senior author of the study.

This inability to shut out external or semantic details when recalling personally-experienced memories is related to mental control over memory recall, adding to a growing body of evidence that altered memory processing may be a vulnerability factor for PTSD.

A second study, in preparation for publication, involves functional brain imaging of 10 of the passengers from Air Transat Flight 236. The aim is to illuminate the brain mechanisms associated with exposure to this traumatic event.

(Source: baycrest.org)

Filed under PTSD memory memory processing psychology neuroscience science

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New Study Points to a Brain Region Key to Contextual Memories

Dartmouth researchers demonstrate in a new study that a previously understudied part of the brain, the retrosplenial cortex, is essential for forming the basis for contextual memories, which help you to recall events ranging from global disasters to where you parked your car.

An important aspect of memory is the ability to recall the physical place, or context, in which an event occurred. For example, in recalling emotionally charged events such as the September 11 terror attacks or the assassination of President John F. Kennedy, we remember not only the event but also where we were when it happened. Indeed, in discussing such events with others, we often ask, “Where were you when … ?” Processing “where” information is also important for mundane events such as remembering where you parked your car.

Although it is known that a specific network of brain regions is important for contextual memory, it has not been known how different parts of the network contribute to this process. But using a newly developed technology known as “chemogenetics,” Professor David Bucci’s laboratory is beginning to show how different brain structures contribute to contextual learning and memory. Developed at the University of North Carolina School of Medicine, the chemogenetics technique enables researchers to “remotely control” the activity of brains cells. This is accomplished by using a virus to transfers genes for a synthetic receptor into a brain region. The receptors are responsive only to a synthetic drug that is administered through a simple injection. By binding to the receptors, the drug temporarily turns off—or on—brain cells in that region for a short amount of time.

Using this approach, Bucci’s laboratory demonstrated in an experiment with rats that the retrosplenial cortex is critical for forming the basis for contextual memories. It was the first time the chemogenetics technique had been used to turn off cells along the entire retrosplenial cortex. The importance of this finding is underscored by two recent studies showing that the hippocampus, another key brain region involved in contextual memories, is not itself active or necessary for forming the initial associations that underlie contextual memory.

The National Science Foundation recently awarded Bucci a five-year, $725,000 grant to continue this research.

“By providing new insight into the function of this part of the brain, our work will also have implications for understanding the basis for illnesses that impact contextual memory, such as Alzheimer’s disease,” Bucci says. “In fact, recent studies have shown that the retrosplenial cortex is one of the first brain areas that is damaged in persons with Alzheimer’s disease.”

The findings appear in The Journal of Neuroscience.

(Source: now.dartmouth.edu)

Filed under retrosplenial cortex contextual memory memory brain cells chemogenetics neuroscience science

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Treating Mental Illness by Changing Memories of Things Past
In the novel À larecherche du temps perdu (translated into English as Remembrance of Things Past), Marcel Proust makes a compelling case that our identities and decisions are shaped in profound and ongoing ways by our memories.
This truth is powerfully reflected in mental illnesses,like post traumatic stress disorder (PTSD) and addictions. In PTSD, memories of traumas intrude vividly upon consciousness, causing distress, driving people to avoid reminders of their traumas, and increasing risk for addiction and suicide. In addiction, memories of drug use influence reactions to drug-related cues and motivate compulsive drug use.
What if one could change these dysfunctional memories? Although we all like to believe that our memories are reliable and permanent, it turns out that memories may indeed be plastic.
The process for modifying memories, depicted in the graphic, is called memory reconsolidation. After memories are formed and stored, subsequent retrieval may make them unstable. In other words, when a memory is activated, it also becomes open to revision and reconsolidation in a new form.
"Memory reconsolidation is probably among the most exciting phenomena in cognitive neuroscience today. It assumes that memories may be modified once they are retrieved which may give us the great opportunity to change seemingly robust, unwanted memories," explains Dr. Lars Schwabe of Ruhr-University Bochum in Germany. He and his colleagues have authored a review paper on the topic, published in the current issue of Biological Psychiatry.
The idea of memory reconsolidation was initially discovered and demonstrated in rodents.
The first evidence of reconsolidation in humans was reported in a study in 2003, and the findings have since continued to accumulate. The current report summarizes the most recent findings on memory reconsolidation in humans and poses additional questions that must be answered by future studies.
"Reconsolidation appears to be a fundamental process underlying cognitive and behavioral therapies. Identifying its roles and mechanisms is an important step forward to fully harnessing the reconsolidation process in psychotherapy," said Dr. John Krystal, Editor of Biological Psychiatry.
The translation of the animal data to humans is a vital step for the potential application of memory reconsolidation in the context of mental disorders. Memory reconsolidation could open the door to novel treatment approaches for disorders such as PTSD or drug addiction.

Treating Mental Illness by Changing Memories of Things Past

In the novel À larecherche du temps perdu (translated into English as Remembrance of Things Past), Marcel Proust makes a compelling case that our identities and decisions are shaped in profound and ongoing ways by our memories.

This truth is powerfully reflected in mental illnesses,like post traumatic stress disorder (PTSD) and addictions. In PTSD, memories of traumas intrude vividly upon consciousness, causing distress, driving people to avoid reminders of their traumas, and increasing risk for addiction and suicide. In addiction, memories of drug use influence reactions to drug-related cues and motivate compulsive drug use.

What if one could change these dysfunctional memories? Although we all like to believe that our memories are reliable and permanent, it turns out that memories may indeed be plastic.

The process for modifying memories, depicted in the graphic, is called memory reconsolidation. After memories are formed and stored, subsequent retrieval may make them unstable. In other words, when a memory is activated, it also becomes open to revision and reconsolidation in a new form.

"Memory reconsolidation is probably among the most exciting phenomena in cognitive neuroscience today. It assumes that memories may be modified once they are retrieved which may give us the great opportunity to change seemingly robust, unwanted memories," explains Dr. Lars Schwabe of Ruhr-University Bochum in Germany. He and his colleagues have authored a review paper on the topic, published in the current issue of Biological Psychiatry.

The idea of memory reconsolidation was initially discovered and demonstrated in rodents.

The first evidence of reconsolidation in humans was reported in a study in 2003, and the findings have since continued to accumulate. The current report summarizes the most recent findings on memory reconsolidation in humans and poses additional questions that must be answered by future studies.

"Reconsolidation appears to be a fundamental process underlying cognitive and behavioral therapies. Identifying its roles and mechanisms is an important step forward to fully harnessing the reconsolidation process in psychotherapy," said Dr. John Krystal, Editor of Biological Psychiatry.

The translation of the animal data to humans is a vital step for the potential application of memory reconsolidation in the context of mental disorders. Memory reconsolidation could open the door to novel treatment approaches for disorders such as PTSD or drug addiction.

Filed under hippocampus memory memory reconsolidation PTSD drug addiction neuroscience science

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Dementia Risk Quadrupled in People with Mild Cognitive Impairment

In a long-term, large-scale population-based study of individuals aged 55 years or older in the general population researchers found that those diagnosed with mild cognitive impairment (MCI) had a four-fold increased risk of developing dementia or Alzheimer’s disease (AD) compared to cognitively healthy individuals. Several risk factors including older age, positive APOE-ɛ4 status, low total cholesterol levels, and stroke, as well as specific MRI findings were associated with an increased risk of developing MCI. The results are published in a supplement to the Journal of Alzheimer’s Disease.

“Mild cognitive impairment has been identified as the transitional stage between normal aging and dementia,” comments M. Arfan Ikram, MD, PhD, a neuroepidemiologist at Erasmus MC University Medical Center (Rotterdam). “Identifying persons at a higher risk of dementia could postpone or even prevent dementia by timely targeting modifiable risk factors.”

Unlike a clinical trial, the Rotterdam study is an observational cohort study focusing on the general population, instead of persons referred to a memory clinic. The Rotterdam study began in 1990, when almost 8,000 inhabitants of Rotterdam aged 55 years or older agreed to participate in the study. Ten years later, another 3,000 individuals were added. Participants undergo home interviews and examinations every four years.

“This important prospective study adds to the accumulating evidence that strokes, presumably related to so called ‘vascular’ risk factors, also contribute to the appearance of dementia in Alzheimer’s disease. This leads to the conclusion that starting at midlife people should minimize those risk factors. The recent results of the Finish FINGER study corroborate this idea. It should be remembered that delaying the onset of dementia by five years will reduce the prevalence of the disease by half. And of course, since there is no cure for AD, prevention is the best approach at present,” explains Professor Emeritus Amos D Korczyn, Tel Aviv University, Ramat Aviv, Israel, and Guest Editor of the Supplement.

To be diagnosed with MCI in the study, individuals were required to meet three criteria: a self-reported awareness of having problems with memory or everyday functioning; deficits detected on a battery of cognitive tests; and no evidence of dementia. They were categorized into those with memory problems (amnestic MCI) and those with normal memory (non-amnestic MCI).

Of 4,198 persons found to be eligible for the study, almost 10% were diagnosed with MCI. Of these, 163 had amnestic MCI and 254 had non-amnestic MCI.

The risk of dementia was especially high for people with amnestic MCI. Similar results were observed regarding the risk for Alzheimer’s disease. Those with MCI also faced a somewhat higher risk of death. 

The research team investigated possible determinants of MCI, considering factors such as age, APOE-ɛ status, waist circumference, hypertension, diabetes mellitus, total and HDL-cholesterol levels, smoking, and stroke. Only older age, being an APOE-ɛ4 carrier, low total cholesterol levels, and stroke at baseline were associated with developing MCI. Having the APOE-ɛ4 genotype and smoking were related only to amnestic MCI.

When the investigators analysed MRI studies of the brain, they found that participants with MCI, particularly those with non-amnestic MCI, had larger white matter lesion volumes and worse microstructural integrity of normal-appearing white matter compared to controls. They were also three-times more likely than controls to have lacunes (3 to 15 mm cerebrospinal fluid (CSF)-filled cavities in the basal ganglia or white matter, frequently observed when imaging older people). MCI was not associated with total brain volume, hippocampal volume, or cerebral microbleeds.

“Our results suggest that accumulating vascular damage plays a role in both amnestic and non-amnestic MCI,” says Dr. Ikram. “We propose that timely targeting of modifiable vascular risk factors might contribute to the prevention of MCI and dementia.”

Reference:

Determinants, MRI Correlates, and Prognosis of Mild Cognitive Impairment: The Rotterdam Study. Renée F.A.G. de Bruijn, Saloua Akoudad, Lotte G.M. Cremers, Albert Hofman, Wiro J. Niessen, Aad van der Lugt, Peter J. Koudstaal, Meike W. Vernooij, M. Arfan Ikram. Journal of Alzheimer’s Disease, Volume 42/Supplement 3 (August 2014): 2013 International Congress on Vascular Dementia (Guest Editor: Amos D. Korczyn)

(Source: iospress.nl)

Filed under cognitive impairment dementia alzheimer's disease memory brain structure neuroscience science

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Eating Baked or Broiled Fish Weekly Boosts Brain Health
Eating baked or broiled fish once a week is good for the brain, regardless of how much omega-3 fatty acid it contains, according to researchers at the University of Pittsburgh School of Medicine. The findings, published online recently in the American Journal of Preventive Medicine, add to growing evidence that lifestyle factors contribute to brain health later in life.
Scientists estimate that more than 80 million people will have dementia by 2040, which could become a substantial burden to families and drive up health care costs, noted senior investigator James T. Becker, Ph.D., professor of psychiatry, Pitt School of Medicine. Some studies have predicted that lifestyle changes such as a reduction in rates of physical inactivity, smoking and obesity could lead to fewer cases of Alzheimer’s disease and other conditions of cognitive impairment in the elderly. The anti-oxidant effect of omega-3 fatty acids, which are found in high amounts in fish, seeds and nuts, and certain oils, also have been associated with improved health, particularly brain health.
“Our study shows that people who ate a diet that included baked or broiled, but not fried, fish have larger brain volumes in regions associated with memory and cognition,” Dr. Becker said. “We did not find a relationship between omega-3 levels and these brain changes, which surprised us a little. It led us to conclude that we were tapping into a more general set of lifestyle factors that were affecting brain health of which diet is just one part.”
Lead investigator Cyrus Raji, M.D., Ph.D., who now is in radiology residency training at UCLA, and the research team analyzed data from 260 people who provided information on their dietary intake, had high-resolution brain MRI scans, and were cognitively normal at two time points during their participation in the Cardiovascular Health Study (CHS), a 10-year multicenter effort that began in 1989 to identify risk factors for heart disease in people over 65.
“The subset of CHS participants answered questionnaires about their eating habits, such as how much fish did they eat and how was it prepared,” Dr. Raji said. “Baked or broiled fish contains higher levels of omega-3s than fried fish because the fatty acids are destroyed in the high heat of frying, so we took that into consideration when we examined their brain scans.”
People who ate baked or broiled fish at least once a week had greater grey matter brain volumes in areas of the brain responsible for memory (4.3 percent) and cognition (14 percent) and were more likely to have a college education than those who didn’t eat fish regularly, the researchers found. But no association was found between the brain differences and blood levels of omega-3s.
“This suggests that lifestyle factors, in this case eating fish, rather than biological factors contribute to structural changes in the brain,” Dr. Becker noted. “A confluence of lifestyle factors likely are responsible for better brain health, and this reserve might prevent or delay cognitive problems that can develop later in life.”

Eating Baked or Broiled Fish Weekly Boosts Brain Health

Eating baked or broiled fish once a week is good for the brain, regardless of how much omega-3 fatty acid it contains, according to researchers at the University of Pittsburgh School of Medicine. The findings, published online recently in the American Journal of Preventive Medicine, add to growing evidence that lifestyle factors contribute to brain health later in life.

Scientists estimate that more than 80 million people will have dementia by 2040, which could become a substantial burden to families and drive up health care costs, noted senior investigator James T. Becker, Ph.D., professor of psychiatry, Pitt School of Medicine. Some studies have predicted that lifestyle changes such as a reduction in rates of physical inactivity, smoking and obesity could lead to fewer cases of Alzheimer’s disease and other conditions of cognitive impairment in the elderly. The anti-oxidant effect of omega-3 fatty acids, which are found in high amounts in fish, seeds and nuts, and certain oils, also have been associated with improved health, particularly brain health.

“Our study shows that people who ate a diet that included baked or broiled, but not fried, fish have larger brain volumes in regions associated with memory and cognition,” Dr. Becker said. “We did not find a relationship between omega-3 levels and these brain changes, which surprised us a little. It led us to conclude that we were tapping into a more general set of lifestyle factors that were affecting brain health of which diet is just one part.”

Lead investigator Cyrus Raji, M.D., Ph.D., who now is in radiology residency training at UCLA, and the research team analyzed data from 260 people who provided information on their dietary intake, had high-resolution brain MRI scans, and were cognitively normal at two time points during their participation in the Cardiovascular Health Study (CHS), a 10-year multicenter effort that began in 1989 to identify risk factors for heart disease in people over 65.

“The subset of CHS participants answered questionnaires about their eating habits, such as how much fish did they eat and how was it prepared,” Dr. Raji said. “Baked or broiled fish contains higher levels of omega-3s than fried fish because the fatty acids are destroyed in the high heat of frying, so we took that into consideration when we examined their brain scans.”

People who ate baked or broiled fish at least once a week had greater grey matter brain volumes in areas of the brain responsible for memory (4.3 percent) and cognition (14 percent) and were more likely to have a college education than those who didn’t eat fish regularly, the researchers found. But no association was found between the brain differences and blood levels of omega-3s.

“This suggests that lifestyle factors, in this case eating fish, rather than biological factors contribute to structural changes in the brain,” Dr. Becker noted. “A confluence of lifestyle factors likely are responsible for better brain health, and this reserve might prevent or delay cognitive problems that can develop later in life.”

Filed under omega-3 fish consumption brain structure gray matter dementia memory cognition neuroscience science

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Problem drinking in midlife doubles chance of memory problems in later life

A study published in the American Journal of Geriatric Psychiatry indicates that middle-aged adults with a history of problem drinking are more than twice as likely to suffer from severe memory impairment in later life.

The study highlights the hitherto largely unknown link between harmful patterns of alcohol consumption and problems with memory later in life – problems which may place people at a high risk of developing dementia.

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The study was carried out by researchers from the University of Exeter Medical School with support from the NIHR Collaboration for Leadership in Applied Health Research and Care South West Peninsula (NIHR PenCLAHRC).

The research team studied the association between a history of alcohol use disorders (AUDs) and the onset of severe cognitive and memory impairment in 6542 middle-aged adults born between 1931 and 1941. These individuals participated in the Health and Retirement Study in the US.

Participants were first assessed in 1992 and follow-up assessments took place every other year from 1996 to 2010.

A history of AUDs was identified using the CAGE* questionnaire (short for Cut down, Annoyed, Guilty, Eye-opener). Where participants registered a history of AUDs their chances of developing severe memory impairment more than doubled.

The study was led by Dr Iain Lang. He commented: “We already know there is an association between dementia risk and levels of current alcohol consumption – that understanding is based on asking older people how much they drink and then observing whether they develop problems. But this is only one part of the puzzle and we know little about the consequences of alcohol consumption earlier in life. What we did here is investigate the relatively unknown association between having a drinking problem at any point in life and experiencing problems with memory later in life.”

He added: “This finding – that middle-aged people with a history of problem drinking more than double their chances of memory impairment when they are older – suggests three things: that this is a public health issue that needs to be addressed; that more research is required to investigate the potential harms associated with alcohol consumption throughout life; and that the CAGE questionnaire may offer doctors a practical way to identify those at risk of memory/cognitive impairment and who may benefit from help to tackle their relationship with alcohol.”

Dr Doug Brown, Director of Research and Development at Alzheimer’s Society said: “When we talk about drinking too much, the media often focuses on young people ending up in A&E after a night out. However, there’s also a hidden cost of alcohol abuse given the mounting evidence that alcohol abuse can also impact on cognition later in life. This small study shows that people who admitted to alcohol abuse at some point in their lives were twice as likely to have severe memory problems, and as the research relied on self-reporting that number may be even higher.

"This isn’t to say that people need to abstain from alcohol altogether. As well as eating a healthy diet, not smoking and maintaining a healthy weight, the odd glass of red wine could even help reduce your risk of developing dementia."

* The CAGE asks four questions (and the acronym comes from words in each question: Cut down, Annoyed, Guilty, Eye-opener):

  1. Have you ever felt you should cut down on your drinking?
  2. Have people annoyed you by criticising your drinking?
  3. Have you ever felt bad or guilty about your drinking?
  4. Have you ever had a drink first thing in the morning to steady your nerves or get rid of a hangover (eye-opener)?

(Source: exeter.ac.uk)

Filed under memory alcohol alcohol use disorders cognitive impairment dementia neuroscience science

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