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Data Mining Reveals the Six Basic Emotional Arcs of Storytelling - MIT Technology Review

The idea behind sentiment analysis is that words have a positive or negative emotional impact. So words can be a measure of the emotional valence of the text and how it changes from moment to moment. So measuring the shape of the story arc is simply a question of assessing the emotional polarity of a story at each instant and how it changes. Reagan and co do this by analyzing the emotional polarity of “word windows” and sliding these windows through the text to build up a picture of how the emotional valence changes. They performed this task on over 1,700 English works of fiction that had each been downloaded from the Project Gutenberg website more than 150 times.

A new way by which the human brain marks time: Novel findings may further understanding of age-related dementia -- ScienceDaily

In the UCI study, participants sat with their heads inside a high-resolution fMRI scanner while watching the TV show and then viewing still frames from the episode, one at a time. The researchers found that when subjects had more precise answers to questions about what time certain events occurred, they activated a brain network involving the lateral entorhinal cortex and the perirhinal cortex. The team had previously shown that these regions, which surround the hippocampus, are associated with memories of objects or items but not their spatial location. Until now, little had been known about how this network might process and store information about time. "The field of neuroscience has focused extensively on understanding how we encode and store information about space, but time has always been a mystery," said Yassa, a professor of neurobiology & behavior. "This study and the Moser team's study represent the first cross-species evidence for a potential role of the lateral entorhinal cortex in storing and retrieving information about when experiences happen." "Space and time have always been intricately linked, and the common wisdom in our field was that the mechanisms involved in one probably supported the other as well," added Maria Montchal, a graduate student in Yassa's lab who led the research. "But our results suggest otherwise."

Near bottom: focus triggered by new activity or movement?

Research has shown that the electrical activity of the neocortex of the brain changes, when we focus our attention. Neurons stop signalling in sync with one another and start firing out of sync. This is helpful, says Williams, because it allows individual neurons to respond to sensory information in different ways. Thus, you can focus on a car speeding down the road or on what a friend is saying in a crowded room. It's known that the cholinergic system in the brain plays an important role in triggering this desynchronization. The cholinergic system consists of clusters of special neurons that synthesise and release a signalling molecule called acetylcholine, he explains, and these clusters make far reaching connections throughout the brain. Not only does this cholinergic system act like a master switch, but mounting evidence suggests it also enables the brain to identify which sensory input is the most salient -- i.e. worthy of attention -- at any given moment and then shine a spotlight on that input. "The cholinergic system broadcasts to the brain, 'this thing is really important to be vigilant to'," says Williams. He adds that the cholinergic system has been proposed to have a far-reaching impact on our cognitive abilities. "Destruction of the cholinergic system in animals profoundly degrades cognition, and the formation of memory," he says. "Importantly, in humans a progressive degeneration of the cholinergic system occurs in devastating diseases that blunt cognition and memory, such as Alzheimer's disease." But precisely which neurons in the cortex are being targeted by this master switch and how it's able to influence their function was unknown. Williams and QBI researcher Lee Fletcher wondered if layer 5 B-pyramidal neurons, the 'output' neurons of the neocortex, might be involved, because they are intimately involved in how we perceive the world. "The output neurons of the neocortex perform computations that are thought to underlie our perception of the world," says Williams. Williams and Fletcher wanted to know if the cholinergic system is able to influence the activity of these output neurons. Using a technique called optogenetics, they modified neurons in the cholinergic system in the brains of mice so that they could be activated with a flash of blue light, triggering a sudden release of acetylcholine. This allowed the researchers to closely monitor the interaction between the cholinergic system and the output neurons. They discovered that if the output neurons were not currently active, not much happened. But when those neurons received excitatory input to their dendrites, the cholinergic system was able to massively increase their activity. "It's as if the cholinergic system has given a 'go' signal," says Fletcher, enabling the output neurons of the neocortex to powerfully respond. Importantly, this change was selective, and only apparent when excitatory input was being processed in the dendrites of the 'output' neurons. "We have known for some time that the dendrites of the output neurons of the neocortex only become active when animals are actively performing a behaviour, and that this activity is correlated with perception and task performance," says Williams. This new work demonstrates that the cholinergic system is critical to this transition in mice and rats, allowing the output neurons to perform computations in a state-dependent manner. "We suggest that this switch also occurs in the human neocortex, allowing us to rapidly switch our state of vigilance and attention," says Williams. "Our work therefore provides important insight into how the progressive degeneration of the cholinergic system in disease blunts human cognition."

How the brain reacts to loss of vision: Going blind affects all senses, and disrupts memory ability -- ScienceDaily

Before any changes had developed in the sensory cortices, the researchers observed that loss of vision was first followed by changes in the density of neurotransmitter receptors and impairments of synaptic plasticity in the hippocampus. In subsequent months, hippocampal plasticity became more impaired and spatial memory was affected. During this time the density of neurotransmitter receptors also changed in the visual cortex, as well as in other cortical areas that process other sensory information. "After blindness occurs, the brain tries to compensate for the loss by ramping up its sensitivity to the missing visual signals," explains Denise Manahan-Vaughan, who led the study. When this fails to work, the other sensory modalities begin to adapt and increase their acuities. "Our study shows that this process of reorganisation is supported by extensive changes in the expression and function of key neurotransmitter receptors in the brain. This is a major undertaking, during which time the hippocampus' ability to store spatial experiences is hampered," says Manahan-Vaughan.

Ant Colonies Retain Memories That Outlast the Lifespans of Individuals | Science | Smithsonian

Colonies live for 20-30 years, the lifetime of the single queen who produces all the ants, but individual ants live at most a year. In response to perturbations, the behavior of older, larger colonies is more stable than that of younger ones. It is also more homeostatic: the larger the magnitude of the disturbance, the more likely older colonies were to focus on foraging than on responding to the hassles I had created; while, the worse it got, the more the younger colonies reacted. In short, older, larger colonies grow up to act more wisely than younger smaller ones, even though the older colony does not have older, wiser ants. Ants use the rate at which they meet and smell other ants, or the chemicals deposited by other ants, to decide what to do next. A neuron uses the rate at which it is stimulated by other neurons to decide whether to fire. In both cases, memory arises from changes in how ants or neurons connect and stimulate each other. It is likely that colony behavior matures because colony size changes the rates of interaction among ants. In an older, larger colony, each ant has more ants to meet than in a younger, smaller one, and the outcome is a more stable dynamic. Perhaps colonies remember a past disturbance because it shifted the location of ants, leading to new patterns of interaction, which might even reinforce the new behavior overnight while the colony is inactive, just as our own memories are consolidated during sleep. Changes in colony behavior due to past events are not the simple sum of ant memories, just as changes in what we remember, and what we say or do, are not a simple set of transformations, neuron by neuron. Instead, your memories are like an ant colony’s: no particular neuron remembers anything although your brain does.

Ant Colonies Retain Memories That Outlast the Lifespans of Individuals | Science | Smithsonian

From day to day, the colony’s behavior changes, and what happens on one day affects the next. I conducted a series of perturbation experiments. I put out toothpicks that the workers had to move away, or blocked the trails so that foragers had to work harder, or created a disturbance that the patrollers tried to repel. Each experiment affected only one group of workers directly, but the activity of other groups of workers changed, because workers of one task decide whether to be active depending on their rate of brief encounters with workers of other tasks. After just a few days repeating the experiment, the colonies continued to behave as they did while they were disturbed, even after the perturbations stopped. Ants had switched tasks and positions in the nest, and so the patterns of encounter took a while to shift back to the undisturbed state. No individual ant remembered anything but, in some sense, the colony did.

A December Night in Chapel Hill

The gathering took place on a bristly cold December night for Chapel Hill. The evening started with a group of carolers, including James and his girlfriend of the moment—yes, it was Joni Mitchell—lighting out from the Taylors’ and rambling through the neighborhood from house to house. Ike went along, too, his voice resonant and booming. It would have been just like my parents to join in such a sing-along. My mother had a beautiful voice, and as my father used to say about singers like himself: If you can’t sing, at least sing loud.  I can imagine the smell of that night, woodsmoke flirting with the December air, the scent of pine and fallen leaves. David was seventeen. His older brother Louis was there, too. So was his friend Isabelle Patterson, whom he had picked up on his motorcycle, much to her dad’s distress. The other Taylor siblings were away, probably up north. As the carolers circled around Morgan Creek, David lip-synched his way through “Silent Night,” in part so that he could listen to James and Joni sing. Why listen to himself when such beautiful voices were ringing out behind his ears? Plus he was Jewish and didn’t know the lyrics.  David had treasured James’s friendship from childhood. When David was seven or eight, he’d been helping a group of older boys build a tree house in the woods near Morgan Creek. When they finished, the boys shooed him away. “This is our clubhouse,” they said. He slunk home, head down. James, then thirteen, walking up the road, saw him. “What’s wrong?” he asked. David told him. “Come with me,” James said. They went to the Taylor house, picked up hammers and nails, and proceeded to build David a tree house of his own.  The carolers stopped by the UNC basketball coach Dean Smith’s midcentury modern. He wasn’t quite as exalted in 1970 as he would become, but he was still local royalty. They sang to Dean and his then-wife, Ann. In the years after that, Smith would sometimes drive players he was recruiting through the neighborhood in one of his Carolina-blue Cadillacs. “That’s James Taylor’s house,” he’d tell them. Late in Smith’s career (and well along in Taylor’s), he said that to a recruit, who responded, “Who’s James Taylor?” “He’s a local musician,” Smith said.  When everyone finished caroling, they went back to the Taylors’, gathering upstairs around the fire in the open living room. Nearby stood a Christmas tree that Ike and James had gone into the woods and cut down. Decades later, Isabelle Patterson would tell David that whenever she hears Joni Mitchell’s song “River” (“It’s coming on Christmas, they’re cutting down trees”), she’s convinced that the song was inspired by that visit. That evening, David plopped down on the floor next to Joni. She struck him as shy but very kind and very beautiful. “Is this your dulcimer?” he asked.  “Yes, would you like to see it?” she said. She took the dulcimer out of the case and talked a little about it. When she did that, James pulled his guitar out and they began to play together, as they had in London at the Paris Theatre earlier that fall in a concert broadcast by the BBC. They performed “A Case of You,” “California,” and “Carey,” from Joni Mitchell’s forthcoming album, the epochal Blue, which would be released in the summer of 1971.  James and Joni also played “You’ve Got a Friend,” “Fire and Rain,” and a song-in-progress called “Long Ago and Far Away.” David had already been privileged to hear perhaps the first finished version of “Fire and Rain,” which Taylor completed in Chapel Hill after returning from London. He and James’s youngest brother, Hugh, had been hanging out at the Taylors’ when James asked if they wanted to hear a new song. They listened. “Yeah, I think that’ll be a hit,” David told him. That night, when the gathering finally came to a close and the guests got up to leave, James stood up and sang them off with his version of “Happy Trails,” originally performed by Roy Rogers and Dale Evans. The guests sang along, my parents included, as they disappeared into the night and the rest of their lives.

Touch can produce detailed, lasting memories -- ScienceDaily

Participants showed almost perfect recall on the test that followed the exploration period, correctly identifying the object they had explored 94% of the time. Remarkably, participants still showed robust memory for the original objects 1 week later, with 84% accuracy. But would they still remember objects so well if they weren't intentionally memorizing them? And could objects that were explored by touch be recognized via a different sensory modality? In a second experiment, a new group of participants explored the same 168 objects without knowing they would be tested on them. Instead, the experimenters said that they were investigating aesthetic judgments, and they asked the participants to rate the pleasantness of each object based on texture, shape, and weight. Participants returned 1 week later for a surprise memory test, completing a blindfolded touch-based recognition task for half of the objects. For the rest of the objects, they completed a visual recognition task, in which they saw the original object and a similar object placed on a table, and indicated which one they previously explored. After each trial, the participants also reported if they answered based on recalling details of their touch-based exploration, feeling a vague familiarity, or simply guessing. Again, the results showed that participants remembered the objects with high accuracy. In the blindfolded test, participants answered correctly on 79% of the trials. In the cross-modal visual test, participants identified the correct object 73% of the time.

The Human Brain Is a Time Traveler - The New York Times

In 2001, Randy Buckner’s adviser at Washington University, Marcus Raichle, coined a new term for the phenomenon: the “default-mode network,” or just “the default network.” The phrase stuck. Today, Google Scholar lists thousands of academic studies that have investigated the default network. “It looks to me like this is the most important discovery of cognitive neuroscience,” says the University of Pennsylvania psychologist Martin Seligman. The seemingly trivial activity of mind-wandering is now believed to play a central role in the brain’s “deep learning,” the mind’s sifting through past experiences, imagining future prospects and assessing them with emotional judgments: that flash of shame or pride or anxiety that each scenario elicits.

The Human Brain Is a Time Traveler - The New York Times

In her 1995 paper, Nancy Andreasen included two key observations that would grow in significance over the subsequent decades. When she interviewed the subjects afterward, they described their mental activity during the REST state as a kind of effortless shifting back and forth in time. “They think freely about a variety of things,” Andreasen wrote, “especially events of the past few days or future activities of the current or next several days.” Perhaps most intriguing, Andreasen noted that most of the REST activity took place in what are called the association cortices of the brain, the regions of the brain that are most pronounced in Homo sapiens compared with other primates and that are often the last to become fully operational as the human brain develops through adolescence and early adulthood. “Apparently, when the brain/mind thinks in a free and unencumbered fashion,” she wrote, “it uses its most human and complex parts.”

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.