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Exercise and memory mechanisms

Mice were given cocaine injections over four days in special chambers with a distinctive floor texture to produce a drug association with that environment. The animals were then housed for 30 days in cages, some of which included a running wheel. The researchers found that mice that exercised on these wheels had lower levels of brain peptides related to myelin, a substance that is thought to help fix memories in place. Re-exposure to the cocaine-associated environment affected running and sedentary mice differently: Compared with sedentary mice, the animals with running wheels showed a reduced preference for the cocaine-associated environment. In addition, the brains of re-exposed runners contained higher levels of hemoglobin-derived peptides, some of which are involved in cell signaling in the brain. Meanwhile, peptides derived from actin decreased in the brains of re-exposed sedentary mice. Actin is involved in learning and memory and is implicated in drug seeking. The researchers say these findings related to peptide changes will help to identify biomarkers for drug dependence and relapse.

'Nested sequences': An indispensable mechanism for forming memories -- ScienceDaily

Which of these sequences, slow or nested, is necessary for the appearance of sequence reactivations, and therefore causes the consolidation of memories during sleep? Using an ingenious system, the researchers discovered what deactivates nested sequences, without affecting slow sequences: the animals are transported on an electric train, in a car with a treadmill (see image). When the treadmill is stopped, the nested sequences disappear; they return when the treadmill starts again. The researchers then observed that after several circuits in the train with the treadmill stopped, place cells in the rats' hippocampi did not reactivate during sleep in the same order as when awake. On the contrary, after one train circuit with the treadmill on, the sequence reactivations are indeed present. So it is these nested theta sequences during movement that are indispensable for the consolidation of memory during sleep.

Memory palaces aren't a metaphor

Electroencephalography readings were taken as 24 participants performed a visual working memory task while at rest and during exercise involving different postures: seated on or pedalling a stationary bicycle, as well as standing or walking on a treadmill. (Visual working memory is the ability to maintain visual information to serve the needs of ongoing tasks.) The investigators found that both aerobic exercise and upright posture improved visual working memory compared with passive and seated conditions. Their analyses also suggest where the neural origins of these observed effects take place.

Hippocampus maps relationship of scenes?

Aya Ben-Yakov and Richard Henson found that the hippocampus responded most strongly to the films at the points that independent observers identified as the end of one event and the beginning of a new one. The researchers found a strong match between these event boundaries and participants’ hippocampal activity, varying according to the degree to which the independent observers agreed on the transition points between events. While watching the two-hour long Forrest Gump, hippocampal response was more strongly influenced by the subjective event boundaries than by what the filmmaker may consider a transition between scenes, such as a change in location.

Working Memory May be More Flexible than Previously Thought - Neuroscience News

They turned this idea into a computational model and tested it on data from nine previously published experiments. In those experiments, human subjects memorized the colors of varying numbers of objects. When asked to reproduce these colors as precisely as possible, the quality of their responses was negatively affected by the number of objects in memory. The model by Van den Berg and Ma accurately mimics this set size effect in all nine datasets. Moreover, their model simulations predict that the objects most relevant for a task are stored more accurately than less important ones, a phenomenon also observed in participants. Lastly, their simulation predicts that the total amount of resources devoted to working memory varies with the number of objects to be remembered. This too is consistent with the results of previous experiments. Working memory thus appears to be more flexible than previously thought. The amount of resources that the brain allocates to working memory is not fixed but could be the result of balancing resource cost against cognitive performance. If this is confirmed, it may be possible to improve working memory by offering rewards, or by increasing the perceived importance of a task.

Unless We Spot Changes, Most Life Experiences are Fabricated From Memories - Neuroscience News

HomeFeatured Unless We Spot Changes, Most Life Experiences are Fabricated From Memories Neuroscience NewsJuly 25, 2018 FeaturedNeurosciencePsychology8 min read Summary: A new psychological model suggests change detection plays a key role in how we construct reality. Source: WUSTL. We may not be able to change recent events in our lives, but how well we remember them plays a key role in how our brains model what’s happening in the present and predict what is likely to occur in the future, finds new research in the Journal of Experimental Psychology: General. “Memory isn’t for trying to remember,” said Jeff Zacks, professor of psychology and brain sciences in Arts & Sciences at Washington University in St. Louis and an author of the study. “It’s for doing better the next time.” The study, co-authored with Chris Wahlheim of the University of North Carolina at Greensboro (UNCG), brings together several emerging theories of brain function to suggest that the ability to detect changes plays a critical role in how we experience and learn from the world around us. Known as “Event Memory Retrieval and Comparison Theory” or EMRC, the model builds on previous research by Zacks and colleagues that suggests the brain continually compares sensory input from ongoing experiences against working models of similar past events that it builds from related memories. When real life does not match the “event model,” prediction errors spike and change detection sets off a cascade of cognitive processing that rewires the brain to strengthen memories for both the older model events and the new experience, the theory contends. “We provide evidence for a theoretical mechanism that explains how people update their memory representations to facilitate their processing of changes in everyday actions of others,” Wahlheim said. “These findings may eventually illuminate how the processing of everyday changes influences how people guide their own actions.” In their current study, Zacks and Wahlheim tested the change detection model with experiments that take advantage of the well-documented fact that older adults often have increased difficulty in recalling details of recent events. Groups of healthy older and younger adults were shown video clips of a woman acting out a series of routine, everyday activities, such as doing dishes or preparing to exercise. One week later, they were shown similar videos in which some event details had been changed. “When viewers tracked the changes in these variation-on-a-theme videos, they had excellent memory for what happened on each day, but when they failed to notice a change, memory was horrible,” Zacks said. “These effects may account for some of the problems older adults experience with memory — in these experiments, older adults were less able to track the changes, and this accounted for some of their lower memory performance.”

Google’s DeepMind is using AI to explore dopamine’s role in learning

In animals, dopamine is believed to reinforce behaviors by strengthening synaptic links in the prefrontal cortex. But the consistency of the neural network’s behavior suggests that dopamine also conveys and encodes information about tasks and rule structures, according to the researchers.

Often overlooked glial cell is key to learning and memory: Biomedical scientists offer simple advice: Keep the brain active -- ScienceDaily

In the lab, the researchers artificially increased levels of ephrin-B1 in mice and then tested them for memory retention. They found that the mice could not remember a behavior they had just learned. In cell culture studies, they added neurons to astrocytes that overexpressed ephrin-B1 and were able to see synapse removal, with the astrocytes "eating up" the synapses. "Excessive loss of synapses is a problem," Ethell said. "The hippocampus, the region of the brain associated primarily with memory, is plastic. Here, new neuronal connections are formed when we learn something new. But the hippocampus has a limited capacity; some connections need to go to 'make space' for new connections -- new memories. To learn, we must first forget." In contrast to an ephrin-B1 increase, when this protein decreases (or is down-regulated) it results in more synapses -- and better learning. The astrocytes, in this case, are not able to attach to the synapses. "But you don't want to remember everything," said Amanda Q Nguyen, a Neuroscience Graduate Program student working in Ethell's lab, and a co-first author of the research paper. "It's all about maintaining a balance: being able to learn but also to forget." Advice the researchers have for the public is simple: keep the brain -- that is, the neurons -- active. "Reading and solving puzzles is a good start," Ethell said.

Waves Move Across the Human Brain to Support Memory - Neuroscience News

“We also found that these traveling waves moved more reliably when subjects performed well while performing a working memory task,” says Joshua Jacobs, assistant professor of biomedical engineering and senior author of the paper. “This indicates that traveling waves are significant for memory and cognition–our findings show that these oscillations are an important mechanism for large-scale coordination in the human brain.”

Neurons ripple while brains rest to lock in memories: How quiet minds encode spatial maps while 'introspecting' -- ScienceDaily

"Animals encode a memory of an environment as they run around," said Kemere, an assistant professor of electrical and computer engineering who specializes in neuroscience. "They form a spatial map as individual neurons are activated in different places. When they're awake in our experiments, they're probably doing that exploration process 40 to 60 percent of the time. "But for the other 40 percent, they're scratching themselves, or they're eating, or they're sort of snoozing," he said. "They're not asleep, but they're paused; I like to call it introspecting." Those periods of introspection provided the critical data for the study that inverted the usual process of matching brain activity to movement while the animals were active. The primary data was gathered over the course of many experiments under the direction of Diba, an associate professor and leader of the Neural Circuits and Memory Lab at Michigan Medicine. As the animals explored either back-and-forth tracks or maze-like environments, electrodes in their brains sensed sharp wave-associated bursts of neural activity called population burst events (PBEs). In these events, between 50,000 and 100,000 neurons all fire within 100 milliseconds and send ripples throughout the brain that are not yet fully understood.

What people think they're doing and what they're doing are very different

They found that: Smartphone usage is repetitive and consistent for each person Future phone checking frequency can be predicted with very little data A standard survey was unable to predict these behaviours For example, the researchers found that if you check your phone 80 times today, you are likely to repeat this behaviour every day. Dr Tom Wilcockson from Lancaster University said: "Multiple checks could indicate an absent minded use of mobile phones, which is habitual and unconscious"

How Dopamine Neurons Contribute to Memory Formation in Humans - Neuroscience News

“What we discovered was that a subset of the dopaminergic neurons responded only when an image was novel, but not when it was familiar. In other words, it indicated if the image was new, but not if something was familiar,” said Jan Kaminski, PhD, first author of the study and a project scientist at Cedars-Sinai. “This is an important new scientific discovery, because it has so far remained unclear how the dopaminergic system contributes to episodic memory formation.”

A heavy working memory load may sink brainwave 'synch' -- ScienceDaily

They suggest that the "coupling," or synchrony, of brain waves among three key regions breaks down in specific ways when visual working memory load becomes too much to handle. "When you reach capacity there is a loss of feedback coupling," said senior author Earl Miller, Picower Professor of Neuroscience at MIT's Picower Institute for Learning and Memory. That loss of synchrony means the regions can no longer communicate with each other to sustain working memory.

People with depression have stronger emotional responses to negative memories: A study investigates the brain mechanisms underlying autobiographical memory disturbance in depression -- ScienceDaily

"This study provides new insights into the changes in brain function that are present in major depression. It shows differences in how memory systems are engaged during emotion processing in depression and how people with the disorder must regulate these systems in order to manage their emotions," said Cameron Carter, MD, Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. The personal memories used to evoke emotion in the study help tap into complex emotional situations that people with MDD experience in their daily lives. The 29 men and women with MDD included in the study reported higher levels of negative emotions when bringing negative memories to mind than 23 healthy comparison people. Using brain imaging, senior author Kevin Ochsner, PhD, of Columbia University and colleagues traced the elevated emotional responses to increased activity in an emotional hub of the brain, called the amygdala, and to interactions between the amygdala and the hippocampus -- a brain region important for memory.

Russia’s only Gulag memorial is redesigned to celebrate the Gulag — Meduza

Viktor Shmyrov, the director of the nonprofit that until recently managed Perm-36, told the BBC that the museum is being maintained, but its public presentation is getting a complete overhaul. “Now it’s a museum about the camp system, but not about political prisoners. There’s nothing said about the repressions or about Stalin,” Shmyrov said.

Running helps brain stave off effects of chronic stress: Exercise protects vital memory and learning functions -- ScienceDaily

"Exercise is a simple and cost-effective way to eliminate the negative impacts on memory of chronic stress," said study lead author Jeff Edwards, associate professor of physiology and developmental biology at BYU. Inside the hippocampus, memory formation and recall occur optimally when the synapses or connections between neurons are strengthened over time. That process of synaptic strengthening is called long-term potentiation (LTP). Chronic or prolonged stress weakens the synapses, which decreases LTP and ultimately impacts memory. Edwards' study found that when exercise co-occurs with stress, LTP levels are not decreased, but remain normal.

Memories and recursion to the mean

The behavioral data revealed that as the rat awaited the second stimulus of the trial, the memory of the first stimulus shifted towards the mean of preceding stimuli. The experiment thus confirmed the sliding of memory towards the expected value, a phenomenon that earlier studies have termed 'contraction bias.'

Eating Salad Every Day Keeps Brains 11 Years Younger and Prevents Dementia, Study Shows

Nutritional epidemiologist Martha Clare Morris and her team at Rush University Medical Center in Chicago found that people who ate one to two servings of leafy green vegetables each day experienced fewer memory problems and cognitive decline compared to people who rarely ate spinach. In fact, Morris estimates that veggie lovers who included about 1.3 servings a day into their diets had brains that were roughly 11 years younger compared to those who consumed the least amount of foods like spinach or kale.

The Effects of Physical Exercise and Cognitive Training on Memory and Neurotrophic Factors | Journal of Cognitive Neuroscience | MIT Press Journals

This study examined the combined effect of physical exercise and cognitive training on memory and neurotrophic factors in healthy, young adults. Ninety-five participants completed 6 weeks of exercise training, combined exercise and cognitive training, or no training (control). Both the exercise and combined training groups improved performance on a high-interference memory task, whereas the control group did not. In contrast, neither training group improved on general recognition performance, suggesting that exercise training selectively increases high-interference memory that may be linked to hippocampal function. Individuals who experienced greater fitness improvements from the exercise training (i.e., high responders to exercise) also had greater increases in the serum neurotrophic factors brain-derived neurotrophic factor and insulin-like growth factor-1. These high responders to exercise also had better high-interference memory performance as a result of the combined exercise and cognitive training compared with exercise alone, suggesting that potential synergistic effects might depend on the availability of neurotrophic factors.

Your brain does not process information and it is not a computer | Aeon Essays

Worse still, even if we had the ability to take a snapshot of all of the brain’s 86 billion neurons and then to simulate the state of those neurons in a computer, that vast pattern would mean nothing outside the body of the brain that produced it. This is perhaps the most egregious way in which the IP metaphor has distorted our thinking about human functioning. Whereas computers do store exact copies of data – copies that can persist unchanged for long periods of time, even if the power has been turned off – the brain maintains our intellect only as long as it remains alive. There is no on-off switch. Either the brain keeps functioning, or we disappear. What’s more, as the neurobiologist Steven Rose pointed out in The Future of the Brain (2005), a snapshot of the brain’s current state might also be meaningless unless we knew the entire life history of that brain’s owner – perhaps even about the social context in which he or she was raised.

Human brain recalls visual features in reverse order than it detects them: Study challenges traditional hierarchy of brain decoding; offers insight into how the brain makes perceptual judgements -- ScienceDaily

The brain appeared to encode one line, then the other, and finally encode their relative orientation. But during decoding, when participants were asked to report the individual angle of each line, their brains used that the lines' relationship -- which angle is greater -- to estimate the two individual angles. "This was striking evidence of participants employing this reverse decoding method," said Dr. Qian. The authors argue that reverse decoding makes sense, because context is more important than details. Looking at a face, you want to assess quickly if someone is frowning, and only later, if need be, estimate the exact angles of the eyebrows. "Even your daily experience shows that perception seems to go from high to low levels," Dr. Qian added.

New insights into how sleep helps the brain to reorganize itself -- ScienceDaily

Dr Julie Seibt, Lecturer in Sleep and Plasticity at the University of Surrey and lead author of the study, said: "Our brains are amazing and fascinating organs -- they have the ability to change and adapt based on our experiences. It is becoming increasingly clear that sleep plays an important role in these adaptive changes. Our study tells us that a large proportion of these changes may occur during very short and repetitive brain waves called spindles. "Sleep spindles have been associated with memory formation in humans for quite some time but nobody knew what they were actually doing in the brain. Now we know that during spindles, specific pathways are activated in dendrites, maybe allowing our memories to be reinforced during sleep. "In the near future, techniques that allow brain stimulation, such as transcranial magnetic stimulation (TMS), could be used to stimulate dendrites with the same frequency range as spindles. This could lead to enhance cognitive functions in patients with learning and memory disorders, such as dementia."

When I left | The Passive Voice | A Lawyer's Thoughts on Authors, Self-Publishing and Traditional Publishing

I had a funny feeling as I saw the house disappear, as though I had written a poem and it was very good and I had lost it and would never remember it again.

Notes to our future selves

In other words, the true purpose of note-taking is transporting states of mind (not just information) through time. This is why pictures, sketches, and diagrams often work better than text. We don’t usually think of them as notes, but songs, smells, and tastes work even better. As HBR puts it: “A visual model becomes one of the most effective tools for minimizing alignment-attrition; a visualization formalizes an emergent idea and solidifies it at a moment in time.” Or as Craig Mod more eloquently says, “To return to a book is to return not just to the text but also to a past self. We are embedded in our libraries. To reread is to remember who we once were, which can be equal parts scary and intoxicating.”

Sleep, dopamine and memory

The study shows that increasing sleep, with either a sleep-promoting drug or by genetic stimulation of the neural sleep circuit, decreases signaling activity by dopamine, while at the same time enhancing memory retention. Conversely, increasing arousal stimulates dopamine signaling and accelerates forgetting. This signal activity isn’t constant but is tied directly to the animal’s arousal level. “Our findings add compelling evidence to support the model that sleep reduces the forgetting signal in the brain, thereby keeping memories intact,” Davis said. “As sleep progresses to deeper levels, dopamine neurons become less reactive to stimuli and this leads to more stable memories.

Neuroscientists identify brain circuit necessary for memory formation: New findings challenge standard model of memory consolidation -- ScienceDaily

The researchers labeled memory cells in three parts of the brain: the hippocampus, the prefrontal cortex, and the basolateral amygdala, which stores memories' emotional associations. Just one day after the fear-conditioning event, the researchers found that memories of the event were being stored in engram cells in both the hippocampus and the prefrontal cortex. However, the engram cells in the prefrontal cortex were "silent" -- they could stimulate freezing behavior when artificially activated by light, but they did not fire during natural memory recall. "Already the prefrontal cortex contained the specific memory information," Kitamura says. "This is contrary to the standard theory of memory consolidation, which says that you gradually transfer the memories. The memory is already there." Over the next two weeks, the silent memory cells in the prefrontal cortex gradually matured, as reflected by changes in their anatomy and physiological activity, until the cells became necessary for the animals to naturally recall the event. By the end of the same period, the hippocampal engram cells became silent and were no longer needed for natural recall. However, traces of the memory remained: Reactivating those cells with light still prompted the animals to freeze. In the basolateral amygdala, once memories were formed, the engram cells remained unchanged throughout the course of the experiment. Those cells, which are necessary to evoke the emotions linked with particular memories, communicate with engram cells in both the hippocampus and the prefrontal cortex.