working memory

Working memory positively associated with higher physical endurance, better cognitive function

Suboptimal cardiovascular health, smoking are associated with less cohesive brain network

December 5, 2017

Science Daily/The Mount Sinai Hospital / Mount Sinai School of Medicine

A positive relationship has been found between the brain network associated with working memory -- the ability to store and process information relevant to the task at hand -- and healthy traits such as higher physical endurance and better cognitive function

 

These traits were associated with greater cohesiveness of the working memory brain network while traits indicating suboptimal cardiovascular and metabolic health, and suboptimal health habits including binge drinking and regular smoking, were associated with less cohesive working memory networks.

 

This is the first study to establish the link between working memory and physical health and lifestyle choices.

 

The results of the study will be published online in Molecular Psychiatry.

 

The research team took brain scans of 823 participants in the Human Connectome Project (HCP), a large brain imaging study funded by the National Institutes of Health, while they performed a task involving working memory, and extracted measures of brain activity and connectivity to create a brain map of working memory. The team then used a statistical method called sparse canonical correlation to discover the relationships between the working memory brain map and 116 measures of cognitive ability, physical and mental health, personality, and lifestyle choices. They found that cohesiveness in the working memory brain map was positively associated with higher physical endurance and better cognitive function. Physical traits such as high body mass index, and suboptimal lifestyle choices including binge alcohol drinking and regular smoking, had the opposite association.

 

"Working memory accounts for individual differences in personal, educational, and professional attainment," said Sophia Frangou, MD, PhD, Professor of Psychiatry at the Icahn School of Medicine at Mount Sinai. "Working memory is also one of the brain functions that is severely affected by physical and mental illnesses. Our study identified factors that can either support or undermine the working memory brain network. Our findings can empower people to make informed choices about how best to promote and preserve brain health."

https://www.sciencedaily.com/releases/2017/12/171205091531.htm

Loss of brain synchrony may explain working memory limits

April 26, 2018

Science Daily/City University London

A new study may have revealed the reasons behind our memory limitations. The researchers found that trying to retain too much information in our working memory leads to a communication breakdown between parts of the brain responsible for maintaining it.

 

Everyday experience makes it obvious -- sometimes frustratingly so -- that our working memory capacity is limited and we can only keep so many things consciously in mind at once. The results of a new study, which is published in the journal Cerebral Cortex, may explain why: The authors 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. This loss of synchrony means the regions can no longer communicate with each other to sustain working memory.

 

Maximum working memory capacity -- for instance the total number of images a person can hold in working memory at the same time -- varies between individuals but averages about seven. This new study tries to understand what causes the memory to have this intrinsic limit.

 

The study's lead author, Dr Dimitris Pinotsis, a lecturer at the Department of Psychology at City, University of London, and a research affiliate at the Department of Brain and Cognitive Sciences at MIT, said: "At peak memory capacity, the brain signals that maintain memories and guide actions based on these memories, reach their maximum. Above this peak, the same signals break down."

 

As researchers have previously correlated working memory capacity with intelligence, understanding what causes working memory to have an intrinsic limit is important because it could also help explain the limited nature of conscious thought and how it might break down in diseases.

 

"Because certain psychiatric diseases can lower capacity, the findings could explain more about how such diseases interfere with thinking," said Professor Earl Miller, the study's senior author and the Picower Professor of Neuroscience at MIT's Picower Institute for Learning and Memory. The study's other author is Dr Timothy Buschman, assistant professor at the Princeton University Neuroscience Institute.

 

To investigate working memory limits, the researchers carried out a detailed statistical analysis of data when animal subjects played a simple game. They had to spot the difference when they were shown a set of squares on a screen and then, after a brief blank screen, a nearly identical set in which one square had changed colour. The number of squares involved, hence the working memory load of each round, varied so that sometimes the task exceeded the animals' capacity.

 

As the animals played, the researchers measured the frequency and timing of brain waves produced by ensembles of neurons in three regions presumed to have an important -- though as yet unknown -- relationship in producing visual working memory: the prefrontal cortex (PFC), the frontal eye fields (FEF), and the lateral intraparietal area (LIP).

 

Using sophisticated mathematical techniques, they found that the regions essentially work as a committee, without much hierarchy, to keep working memory going. They also found changes as working memory approached and then exceeded capacity. In particular, the researchers found that above capacity the PFC's coupling to the FEF and LIP at low frequency stopped.

 

As previous studies have suggested that the PFC's role might be to employ low-frequency waves to provide the feedback the keeps the working memory system in sync, the researchers suggest that when that signal breaks down, the whole enterprise may as well. This observation may also explain why memory capacity has a finite limit.

 

Professor Miller said: "We knew that stimulus load degrades stimulus processing in various brain areas, but we hadn't seen any distinct change that correlated with reaching capacity, but we did see this with feedback coupling. It drops off when the subjects exceeded their capacity. The PFC stops providing feedback coupling to the FEF and LIP."

 

The findings could also help optimise heads-up displays in cars and to develop diagnostic tests for diseases like schizophrenia and dementia, among other applications.

 

"Understanding brain signals at peak load can help us understand the origins of cognitive impairments. This could lead to new therapeutic approaches for people in need, like schizophrenics," said Dr Pinotsis.

 

The US National Institute of Mental Health and the MIT's Picower Institute Innovation Fund supported this study.

https://www.sciencedaily.com/releases/2018/04/180426110502.htm

A heavy working memory load may sink brainwave 'synch'

April 5, 2018

Science Daily/Picower Institute at MIT

When working memory load exceeds capacity, a new study finds, feedback coupling of the prefrontal cortex with other involved regions shuts down.

 

Everyday experience makes it obvious -- sometimes frustratingly so -- that our working memory capacity is limited. We can only keep so many things consciously in mind at once. The results of a new study may explain why: 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.

 

Maximum working memory capacity -- for instance the total number of images a person can hold in working memory at the same time -- varies by individual but averages about four, Miller said. Researchers have correlated working memory capacity with intelligence.

 

Understanding what causes working memory to have an intrinsic limit is therefore important because it could help explain the limited nature of conscious thought and optimal cognitive performance, Miller said.

 

And because certain psychiatric disorders can lower capacity, said Miller and lead author Dimitris Pinotsis, a research affiliate in Miller's lab, the findings could also explain more about how such disorders interfere with thinking.

 

"Studies show that peak load is lower in schizophrenics and other patients with neurological or psychiatric diseases and disorders compared to healthy people," Pinotsis said. "Thus, understanding brain signals at peak load can also help us understand the origins of cognitive impairments."

 

The study's other author is Timothy Buschman, assistant professor at the Princeton University Neuroscience Institute and a former member of the Miller lab.

 

How working memory stops working

 

The new study published in the journal Cerebral Cortex is a detailed statistical analysis of data the Miller lab recorded when animal subjects played a simple game: They had to spot the difference when they were shown a set of squares on a screen and then, after a brief blank screen, a nearly identical set in which one square had changed color. The number of squares involved, hence the working memory load of each round, varied so that sometimes the task exceeded the animals' capacity.

 

As the animals played, the researchers measured the frequency and timing of brain waves produced by ensembles of neurons in three regions presumed to have an important -- though as yet unknown -- relationship in producing visual working memory: the prefrontal cortex (PFC), the frontal eye fields (FEF), and the lateral intraparietal area (LIP).

 

The researchers' goal was to characterize the crosstalk among these three areas, as reflected by patterns in the brain waves, and to understand specifically how that might change as load increased to the point where it exceeded capacity.

 

Though the researchers focused on these three areas, they didn't know how they might work with each other. Using sophisticated mathematical techniques, they tested scores of varieties of how the regions "couple," or synchronize, at high- and low-frequencies. The "winning" structure was whichever one best fit the experimental evidence.

 

"It was very open ended," Miller said. "We modeled all different combinations of feedback and feedforward signals among the areas and waited to see where the data would lead."

 

They found that the regions essentially work as a committee, without much hierarchy, to keep working memory going. They also found changes as load approached and then exceeded capacity.

 

"At peak memory load, the brain signals that maintain memories and guide actions based on these memories, reach their maximum," Pinotsis said. "Above this peak, the same signals break down."

 

In particular, above capacity the PFC's coupling to other regions at low frequency stopped, Miller said.

 

Other research suggests that the PFC's role might be to employ low-frequency waves to provide the feedback the keeps the working memory system in synch. When that signal breaks down, Miller said, the whole enterprise may as well. That may explain why memory capacity has a finite limit. In prior studies, he said, his lab has observed that the information in neurons degrades as load increases, but there wasn't an obvious cut-off where working memory would just stop functioning.

 

"We knew that stimulus load degrades processing in these areas, but we hadn't seen any distinct change that correlated with reaching capacity," he said. "But we did see this with feedback coupling. It drops off when the subjects exceeded their capacity. The PFC stops providing feedback coupling to the FEF and LIP."

 

Two sides to the story

 

Because the study game purposely varied where the squares appeared on the left or right side of the visual field, the data also added more evidence for a discovery Miller and colleagues first reported back in 2009: Visual working memory is distinct for each side of the visual field. People have independent capacities on their left and their right, research has confirmed.

 

The Miller Lab is now working on a new study that tracks how the three regions interact when working memory information must be shared across the visual field.

 

The insights Miller's lab has produced into visual working memory led him to start the company SplitSage, which last month earned a patent for technology to measure people's positional differences in visual working memory capacity. The company hopes to use insights from Miller's research to optimize heads-up displays in cars and to develop diagnostic tests for disorders like dementia among other applications. Miller is the company's chief scientist and Buschman is chair of the advisory board.

 

The more scientists learn about how working memory works, and more generally about how brain waves synchronize higher level cognitive functions, the more ways they may be able to apply that knowledge to help people, Miller said.

 

"If we can figure out what things rhythms are doing and how they are doing them and when they are doing them, we may be able to find a way to strengthen the rhythms when they need to be strengthened," he said.

https://www.sciencedaily.com/releases/2018/04/180405093204.htm

Long-term benefits of improving your toddler's memory skills

Early intervention: New research shows that preschoolers with poor short-term recall are more at risk of dropping out of high school

January 12, 2016

Science Daily/Concordia University

Preschoolers who score lower on a memory task are likely to score higher on a dropout risk scale at the age of 12, new research shows. In a new article, the authors offer suggestions for how parents can help kids improve their kid's memory.

 

"Identifying students who are at risk of eventually dropping out of high school is an important step in preventing this social problem," says Caroline Fitzpatrick, first author of a study recently published in Intelligence, and a researcher at Concordia's PERFORM Centre.

 

She and the study's other researchers, who are affiliated with the Université Sainte-Anne and Université de Montréal, have suggestions for how parents can help kids improve their memory.

 

The study examines responses from 1,824 children at age two and a half, and then at three and a half. That data is then compared to the school-related attitudes and results of these children when they hit grade seven.

 

Results were clear: those that do better on a memory-testing imitation sorting task during toddlerhood are more likely to perform better in school later on -- and therefore more likely to stay in school. The imitation sorting task is specifically effective in measuring working memory, which can be compared to a childs mental workspace.

 

"Our results suggest that early individual differences in working memory may contribute to developmental risk for high school dropout, as calculated from student engagement in school, grade point average and whether or not they previously repeated a year in school," says Fitzpatrick.

 

"When taken together, those factors can identify which 12 year olds are likely to fail to complete high school by the age of 21."

 

Help at home

 

"Preschoolers can engage in pretend play with other children to help them practise their working memory, since this activity involves remembering their own roles and the roles of others," says Linda Pagani of the Université de Montréal, co-senior author.

 

"Encouraging mindfulness in children by helping them focus on their moment-to-moment experiences also has a positive effect on working memory."

 

Pagani also notes that breathing exercises and guided meditation can be practised with preschool and elementary school children. In older kids, vigorous aerobic activity such as soccer, basketball and jumping rope have all been shown to have beneficial effects on concentration and recall.

 

The researchers note that another promising strategy for improving working memory in children is to limit screen time -- video games, smartphones, tablets and television -- which can undermine cognitive control and take time away from more enriching pursuits.

 

"Our findings underscore the importance of early intervention," says Fitzpatick.

 

"Parents can help their children develop strong working memory skills at home, and this can have a positive impact on school performance later in life."

http://www.sciencedaily.com/releases/2016/01/160112125425.htm

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