Posts tagged memory
Articles and news from the latest research reports.
Ecstasy Harms Memory With One Year of Recreational Use
New research published online July 25 by the scientific journal Addiction, gives some of the first information available on the actual risk of using ecstasy. It shows that even in recreational amounts over a relatively short time period, ecstasy users risk specific memory impairments. Further, as the nature of the impairments may not be immediately obvious to the user, it is possible people wouldn’t get the signs that they are being damaged by drug use until it is too late.
According to the study, new ecstasy users who took ten or more ecstasy pills over their first year of use showed decreased function of their immediate and short-term memory compared with their pre-ecstasy performance. These findings are associated with damage of the hippocampus, the area of the brain that oversees memory function and navigation. Interestingly, hippocampal damage is one of the first signs of Alzheimer’s disease, resulting in memory loss and disorientation.
Better Understanding of Memory Retrieval Between Children and Adults
ScienceDaily (July 24, 2012) — Neuroscientists from Wayne State University and the Massachusetts Institute of Technology (MIT) are taking a deeper look into how the brain mechanisms for memory retrieval differ between adults and children. While the memory systems are the same in many ways, the researchers have learned that crucial functions with relevance to learning and education differ.
The team’s findings were published on July 17, 2012, in the Journal of Neuroscience.
According to lead author Noa Ofen, Ph.D., assistant professor in WSU’s Institute of Gerontology and Department of Pediatrics, 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, “The Development of Brain Systems Associated with Successful Memory Retrieval of Scenes,” Ofen and her collaborative team tested the development of neural underpinnings of memory from childhood to young adulthood. The team of researchers exposed participants to pictures of scenes and then showed them the same scenes mixed with new ones 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.
The researchers said that older participants used the cortical regions more than younger participants when correctly retrieving past experiences.
"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."
This study marks the first time that the development of connectivity within memory systems in the brain has been tested, and the results suggest that the brain continues to rearrange connections to achieve adult-like performance during development.
Ofen and her research team plan to continue research in this area, focused on modeling brain network connectivity, and applying these methods to study abnormal brain development.
Source: Science Daily
Strobe Eyewear Training Improves Visual Memory
ScienceDaily (July 23, 2012) — Stroboscopic training, performing a physical activity while using eyewear that simulates a strobe-like experience, has been found to increase visual short-term memory retention, and the effects lasted 24 hours.
(Credit: Image courtesy of Duke University)
Participants completed a memory test that required them to note the identity of eight letters of the alphabet that were briefly displayed on a computer screen. After a variable delay, participants were asked to recall one of the eight letters. On easy-level trials, the recall prompt came immediately after the letters disappeared, but on more difficult trials, the prompt came as late as 2.5 seconds following the display. Because participants did not know which letter they would be asked to recall, they had to retain all of the items in memory.
"Humans have a memory buffer in their brain that keeps information alive for a certain short-lived period," said Greg Appelbaum, assistant professor of psychiatry at Duke University and first author of the study. "Wearing the strobe eyewear during the physical training seemed to boost the ability to retain information in this buffer."
The strobe eyewear disrupts vision by only allowing the user to see glimpses of the world. The user must adjust their visual processing in order to perform normally, and this adjustment produces a lingering benefit; once participants removed the strobe eyewear, there was an observed boost in their visual memory retention, which was found to last 24 hours.
Earlier work by Appelbaum and the project’s senior researcher, Stephen Mitroff, had shown that stroboscopic training improves visual perception, including the ability to detect subtle motion cues and the processing of briefly presented visual information. Yet the earlier study had not determined how long the benefits might last.
"Our earlier work on stroboscopic training showed that it can improve perceptual abilities, but we don’t know exactly how," says Mitroff, associate professor of psychology & neuroscience and member of the Duke Institute for Brain Sciences. "This project takes a big step by showing that these improved perceptual abilities are driven, at least in part, by improvements in visual memory."
"Improving human cognition is an important goal with so many benefits," said Appelbaum, also a member of the Duke Institute for Brain Sciences. "Interestingly, our findings demonstrate one way in which visual experience has the capacity to improve cognition."
Source: Science Daily
Why does vivid memory ‘feel so real?’
Scientists find evidence that real perceptual experience and mental replay share similar brain activation patterns
Toronto, Canada – Neuroscientists have found strong evidence that vivid memory and directly experiencing the real moment can trigger similar brain activation patterns.
The study, led by Baycrest’s Rotman Research Institute (RRI), in collaboration with the University of Texas at Dallas, is one of the most ambitious and complex yet for elucidating the brain’s ability to evoke a memory by reactivating the parts of the brain that were engaged during the original perceptual experience. Researchers found that vivid memory and real perceptual experience share “striking” similarities at the neural level, although they are not “pixel-perfect” brain pattern replications.
The study appears online this month in the Journal of Cognitive Neuroscience, ahead of print publication.
"When we mentally replay an episode we’ve experienced, it can feel like we are transported back in time and re-living that moment again," said Dr. Brad Buchsbaum, lead investigator and scientist with Baycrest’s RRI. "Our study has confirmed that complex, multi-featured memory involves a partial reinstatement of the whole pattern of brain activity that is evoked during initial perception of the experience. This helps to explain why vivid memory can feel so real."
But vivid memory rarely fools us into believing we are in the real, external world – and that in itself offers a very powerful clue that the two cognitive operations don’t work exactly the same way in the brain, he explained.
In the study, Dr. Buchsbaum’s team used functional magnetic resonance imaging (fMRI), a powerful brain scanning technology that constructs computerized images of brain areas that are active when a person is performing a specific cognitive task. A group of 20 healthy adults (aged 18 to 36) were scanned while they watched 12 video clips, each nine seconds long, sourced from YouTube.com and Vimeo.com. The clips contained a diversity of content – such as music, faces, human emotion, animals, and outdoor scenery. Participants were instructed to pay close attention to each of the videos (which were repeated 27 times) and informed they would be tested on the content of the videos after the scan.
A subset of nine participants from the original group were then selected to complete intensive and structured memory training over several weeks that required practicing over and over again the mental replaying of videos they had watched from the first session. After the training, this group was scanned again as they mentally replayed each video clip. To trigger their memory for a particular clip, they were trained to associate a particular symbolic cue with each one. Following each mental replay, participants would push a button indicating on a scale of 1 to 4 (1 = poor memory, 4 = excellent memory) how well they thought they had recalled a particular clip.
Dr. Buchsbaum’s team found “clear evidence” that patterns of distributed brain activation during vivid memory mimicked the patterns evoked during sensory perception when the videos were viewed – by a correspondence of 91% after a principal components analysis of all the fMRI imaging data.
The so-called “hot spots”, or largest pattern similarity, occurred in sensory and motor association areas of the cerebral cortex – a region that plays a key role in memory, attention, perceptual awareness, thought, language and consciousness.
Dr. Buchsbaum suggested the imaging analysis used in his study could potentially add to the current battery of memory assessment tools available to clinicians. Brain activation patterns from fMRI data could offer an objective way of quantifying whether a patient’s self-report of their memory as “being good or vivid” is accurate or not.
Source: EurekAlert!
Music has big brain benefits compared to other leisure pursuits
Music rocks. Musical activity was found to preserve cognition, including memory, as you age, when comparing variability in cognitive outcomes of older adults active in musical instrumental and other leisure activities.
You won’t lose it if you don’t use it. A range of cognitive benefits including memory were sustained for musicians between the ages of 60-80 if they played for at least 10 years throughout their life, confirming the maintenance of advantages is not reliant on continued activity.
Start young. Timing of musical instrumental acquisition, before age nine, is important in optimizing cognitive benefits and was associated with enhanced verbal working memory functions.
It’s never too late, so keep at it. Sustained musical activity over the age of 60 was associated with other nonverbal cognitive benefits, and appeared to compensate for low educational attainment, which is possibly the greatest protection against age-related cognitive declines. This suggests that musical training should be considered an alternative form of education.
Triangles guide the way for live neural circuits in a dish
July 19, 2012
Korean scientists have used tiny stars, squares and triangles as a toolkit to create live neural circuits in a dish.
They hope the shapes can be used to create a reproducible neural circuit model that could be used for learning and memory studies as well as drug screening applications; the shapes could also be integrated into the latest neural tissue scaffolds to aid the regeneration of neurons at injured sites in the body, such as the spinal cord.
Published today in the Journal of Neural Engineering, the study, by researchers at the Korea Advanced Institute of Science and Technology (KAIST), found that triangles were the most effective shape for helping to facilitate the growth of axons and guide them onto specific paths to form a complete circuit.
Co-author of the study, Professor Yoonkey Nam, said: “Eventually, we want to know if we can design a neural tissue model that biologically mimics some neural circuits in our brain.”
A neuron is an electrically excitable cell that processes and transmits information around the body. The neuron is composed of three main parts: a cell body, or soma, dendrites and an axon, which extends from the soma and links to other cells, creating a network.
When axons grow they are usually guided by proteins. Many researchers have been trying to re-create this key process in a dish by manipulating nerve cells from rat brains.
As nerve cells are usually just a few tens of micrometres in size, the challenge associated with creating a live neural network is firstly positioning cells in desired locations and, secondly, making connections between these cells by guiding the axons in designated directions.
The researchers investigated whether two star shapes, five regular shapes (square, circle, triangle, pentagon and hexagon) and three different sizes of isosceles triangles could guide axons in designated directions. Each shape was the size of a single cell and was replicated to form an array which was printed onto a glass surface.
Each of the arrays had an overall size of 1cm-by-1cm with a gap of 10 micrometres between each shape. Hippocampal neurons were taken from rats and plated onto the patterned surfaces. The neurons were fluorescently labelled with dyes so that images could be taken of their growth.
The researchers found that triangles were the most efficient shape to encourage the growth and guidance of an axon. The key to this was the angles at the points where two of the triangle’s lines meet, also known as the vertices. It was shown that the smaller the vertices, the higher chance the triangle had of inducing growth.
"Based on our results, we are suggesting a new design principle for guiding axons in a dish. We can control the axonal growth in a certain direction by putting a sharp triangle pointing to a certain direction. Then, a neuron that adhered to the triangle will have an axon in the sharp vertex direction.
"Overall, we integrated microtechnology with neurobiology to find a new engineering solution" continued Professor Nam.
Provided by Institute of Physics
Source: medicalxpress.com
Synapses are modified through learning. Up until now, scientists believed that a particular form of synaptic plasticity in the brain’s hippocampus was responsible for learning spatial relations. This was based on a receptor type for the neurotransmitter glutamate: the NMDA receptor. Researchers at the Max Planck Institute for Medical Research in Heidelberg and Oxford University have now observed that mice develop a spatial memory, even when the NMDA receptor-transmitted plasticity is switched off in parts of their hippocampus. However, if these mice have to resolve a conflict while getting their bearings, they are not successful in resolving it; the hippocampal NMDA receptors are clearly needed to detect or resolve the conflict. This has led the researchers involved in this experiment to refute a central tenet of neuroscience regarding the function of hippocampal NMDA receptor-transmitted plasticity in spatial learning.
Are cardiac risk factors linked to less blood flow to the brain?
7/18/2012
Metabolic syndrome, a term used to describe a combination of risk factors that often lead to heart disease and type 2 diabetes, seems to be linked to lower blood flow to the brain, according to research by the University of Wisconsin School of Medicine and Public Health.
Dr. Barbara Bendlin, researcher for the Wisconsin Alzheimer’s Disease Research Center and an assistant professor of medicine (geriatrics) at the UW School of Medicine and Public Health, said study participants with multiple risk factors connected to metabolic syndrome, including abdominal obesity, high blood pressure, high blood sugar and high cholesterol averaged 15 percent less blood flow to the brain than those in a control group, according to results of brain scans to measure cerebral blood flow.
"We thought the cerebral blood flow measurements of the metabolic syndrome group would be lower, but it was striking how much lower it was," said Bendlin.
Although lower blood flow could result in an eventual reduction in memory skills, Bendlin said it is not known if people with metabolic syndrome will get Alzheimer’s disease.
"Having metabolic syndrome at middle age does have an effect on the brain, and there is some suggestion that if you have lower blood flow, certain types of memory functions are reduced," she said. "The key will be to follow these people over time, because we want to know if lower blood flow will lead to a gradual loss of memory and cognitive skills. But it’s too early to say if these people will develop Alzheimer’s."
The study, presented today at the Alzheimer’s Association International Conference in Vancouver, British Columbia, involved 71 middle-aged people recruited from the Wisconsin Registry for Alzheimer’s Prevention (WRAP). Of this group, 29 met the criteria for metabolic syndrome and 42 did not.
Bendlin said the next steps will be to conduct additional brain scans on people with metabolic syndrome to get more specifics on why they have reduced cerebral blood flow.
"By comparing people with metabolic syndrome with those who don’t, we don’t know which of the risk factors are worst," she said. "Is having a high blood-glucose level worse than having high blood pressure or is it different than having abdominal obesity? All of these risk factors have been linked to increased risk for dementia, but they are clustered together. If we knew which ones were the worst, those would be the ones to target with specific treatments."
Source: Bio-Medicine
In the insect brain, dopamine-releasing nerve cells are crucial to the formation of both punished and rewarded memories.
Hiromu Tanimoto and his colleagues at the Max Planck Institute of Neurobiology recently localised and identified the most important types of nerve cells involved in forming positive and negative memories of a fruit fly. All four nerve cell types they discovered use dopamine to communicate with other nerve cells. The dopamine signals released by these cells are received in the mushroom body, a prominent brain structure in insect brains. “It is really surprising that similar dopamine-releasing nerve cells can play such different roles,” says Tanimoto.
Read more: Dopamine – A substance with many messages
Drug Shown to Improve Memory in Those With Down Syndrome
ScienceDaily (July 17, 2012) — Researchers at the University of Colorado School of Medicine have found a drug that boosts memory function in those with Down syndrome, a major milestone in the treatment of this genetic disorder that could significantly improve quality of life.
"Before now there had never been any positive results in attempts to improve cognitive abilities in persons with Down syndrome through medication," said Alberto Costa, MD, Ph.D., who led the four- year study at the CU School of Medicine. "This is the first time we have been able to move the needle at all and that means improvement is possible."
The study was published July 17 in the journal Translational Psychiatry.
Costa, an associate professor of medicine, and his colleagues studied 38 adolescents and young adults with Down syndrome. Half took the drug memantine, used to treat Alzheimer’s disease, and the others took a placebo.
Costa’s research team hypothesized that memantine, which improved memory in mice with Down syndrome, could increase test scores of young adults with the disorder in the area of spatial and episodic memory, functions associated with the hippocampus region of the brain.
Participants underwent a 16-week course of either memantine or a placebo while scientists compared the adaptive and cognitive function of the two groups.