Better memory at ideal temperature

People’s working memory functions better if they are working in an ambient temperature where they feel most comfortable. That is what Leiden psychologists Lorenza Colzato and Roberta Sellaro conclude after having conducted research. They are publishing their findings in Psychological Research.

Studied for the first time
Everyone knows from experience that climate and temperature influence how you feel. But what about our ability to think? Does ambient temperature affect that too? The little research that has been done on this question shows that cooler environments promote cognitive performance when performing complex thinking tasks. Colzato and Sellaro are the first to investigate whether a person’s working memory works better when the ambient temperature perfectly matches his or her preference.

N-back test
To study the influence ambient temperature has on cognitive skills, Colzato and Sellaro performed tests on two groups of participants. One group had a preference for a cool environment, the other group preferred a warm one. The test subjects had to carry out thinking tasks in three different spaces. In the first the temperature was 25 degrees Celsius (77 Fahrenheit), in the second it was 15 degrees (59 Fahrenheit), and in the third the thermostat was set to 20 (68 Fahrenheit). The thinking task that the subjects had to perform was the so-called N-back task. Different letters would appear one after the other on the computer screen. Subjects had to indicate whether the letter that they saw was the same as the one they had seen two steps earlier.

Idea confirmed
Test subjects proved to perform better in a room with their preferred temperature. The conjecture is that working in one’s preferred temperature counteracts ‘ego depletion’: sources of energy necessary to be able to carry out mental tasks get used up less quickly. ‘The results confirm the idea that temperature influences cognitive ability. Working in one’s ideal temperature can promote efficiency and productivity,’ according to Colzato and Sellaro.

Head injuries can make children loners

New research has found that a child’s relationships may be a hidden casualty long after a head injury.

Neuroscientists at Brigham Young University studied a group of children three years after each had suffered a traumatic brain injury – most commonly from car accidents. The researchers found that lingering injury in a specific region of the brain predicted the health of the children’s social lives.

“The thing that’s hardest about brain injury is that someone can have significant difficulties but they still look okay,” said Shawn Gale, a neuropsychologist at BYU. “But they have a harder time remembering things and focusing on things as well and that affects the way they interact with other people. Since they look fine, people don’t cut them as much slack as they ought to.”

Gale and Ph.D. student Ashley Levan authored a study to be published April 10 by the Journal of Head Trauma Rehabilitation, the leading publication in the field of rehabilitation. The study compared the children’s social lives and thinking skills with the thickness of the brain’s outer layer in the frontal lobe. The brain measurements came from MRI scans and the social information was gathered from parents on a variety of dimensions, such as their children’s participation in groups, number of friends and amount of time spent with friends.

A second finding from the new study suggests one potential way to help. The BYU scholars found that physical injury and social withdrawal are connected through something called “cognitive proficiency.” Cognitive proficiency is the combination of short-term memory and the brain’s processing speed.

“In social interactions we need to process the content of what a person is saying in addition to simultaneously processing nonverbal cues,” Levan said. “We then have to hold that information in our working memory to be able to respond appropriately. If you disrupt working memory or processing speed it can result in difficulty with social interactions.”

Separate studies on children with ADHD, which also affects the frontal lobes, show that therapy can improve working memory. Gale would like to explore in future research with BYU’s MRI facility if improvements in working memory could “treat” the social difficulties brought on by head injuries.

“This is a preliminary study but we want to go into more of the details about why working memory and processing speed are associated with social functioning and how specific brain structures might be related to improve outcome,” Gale said.

The effects of working memory training on functional brain network efficiency

The human brain is a highly interconnected network. Recent studies have shown that the functional and anatomical features of this network are organized in an efficient small-world manner that confers high efficiency of information processing at relatively low connection cost. However, it has been unclear how the architecture of functional brain networks is related to performance in working memory (WM) tasks and if these networks can be modified by WM training. Therefore, we conducted a double-blind training study enrolling 66 young adults. Half of the subjects practiced three WM tasks and were compared to an active control group practicing three tasks with low WM demand. High-density resting-state electroencephalography (EEG) was recorded before and after training to analyze graph-theoretical functional network characteristics at an intracortical level. WM performance was uniquely correlated with power in the theta frequency, and theta power
was increased by WM training. Moreover, the better a person’s WM performance, the more their network exhibited small-world topology. WM training shifted network characteristics in the direction of high performers, showing increased small-worldness within a distributed fronto-parietal network. Taken together, this is the first longitudinal study that provides evidence for the plasticity of the functional brain network underlying WM.

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New Studies Show Promise for Brain Training in Improving Fluid Intelligence

Whether computerized games designed by psychologists and neuroscientists can literally make people smarter has been hotly debated by scientists, with a small but outspoken cadre of skeptics demanding stronger proof. Now two new studies have found the kind of real-world benefits from the brain-training games that skeptics have been calling for.

The first, published today in the Proceedings of the National Academy of Sciences, found that less than six hours of brain games played over the course of 10 weeks enabled poor first-graders who attend school irregularly due to family problems to catch up with their regularly-attending peers in math and language grades.

The second, presented over the weekend at the Cognitive Neuroscience Society meeting in Boston, combined the results of 13 previous studies of computerized brain-training in young adults to conclude that training significantly enhances fluid intelligence—the fundamental human ability to detect patterns, reason, and learn.  That is, practicing the games literally makes people smarter.  

Together with other recent studies demonstrating real-world benefits of brain training in healthy older adults, preschoolers, and school children with ADHD, the new papers appear to provide fresh ammunition to psychologists and neuroscientists whose research has been under attack by a handful of skeptics who insist that the training is a waste of time.

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Green tea boosts your brain

Green tea is said to have many putative positive effects on health. Now, researchers at the University of Basel are reporting first evidence that green tea extract enhances the cognitive functions, in particular the working memory. The Swiss findings suggest promising clinical implications for the treatment of cognitive impairments in psychiatric disorders such as dementia. The academic journal Psychopharmacology has published their results.

In the past the main ingredients of green tea have been thoroughly studied in cancer research. Recently, scientists have also been inquiring into the beverage’s positive impact on the human brain. Different studies were able to link green tea to beneficial effects on the cognitive performance. However, the neural mechanisms underlying this cognitive enhancing effect of green tea remained unknown.

Better memory

In a new study, the researcher teams of Prof. Christoph Beglinger from the University Hospital of Basel and Prof. Stefan Borgwardt from the Psychiatric University Clinics found that green tea extract increases the brain’s effective connectivity, meaning the causal influence that one brain area exerts over another. This effect on connectivity also led to improvement in actual cognitive performance: Subjects tested significantly better for working memory tasks after the admission of green tea extract.

For the study healthy male volunteers received a soft drink containing several grams of green tea extract before they solved working memory tasks. The scientists then analyzed how this affected the brain activity of the men using magnetic resonance imaging (MRI). The MRI showed increased connectivity between the parietal and the frontal cortex of the brain. These neuronal findings correlated positively with improvement in task performance of the participants. «Our findings suggest that green tea might increase the short-term synaptic plasticity of the brain», says Borgwardt.

Clinical implications

The research results suggest promising clinical implications: Modeling effective connectivity among frontal and parietal brain regions during working memory processing might help to assess the efficacy of green tea for the treatment of cognitive impairments in neuropsychiatric disorders such as dementia.

Study reveals workings of working memory

Keep this in mind: Scientists say they’ve learned how your brain plucks information out of working memory when you decide to act.

Say you’re a busy mom trying to wrap up a work call now that you’ve arrived home. While you converse on your Bluetooth headset, one kid begs for an unspecified snack, another asks where his homework project has gone, and just then an urgent e-mail from your boss buzzes the phone in your purse. During the call’s last few minutes these urgent requests — snack, homework, boss — wait in your working memory. When you hang up, you’ll pick one and act.

When you do that, according to Brown University psychology researchers whose findings appear in the journal Neuron, you’ll employ brain circuitry that links a specific chunk of the striatum called the caudate and a chunk of the prefrontal cortex centered on the dorsal anterior premotor cortex. Selecting from working memory, it turns out, uses similar circuits to those involved in planning motion.

In lab experiments with 22 adult volunteers, the researchers used magnetic resonance imaging to track brain activity during a carefully designed working memory task. They also measured how quickly the subjects could choose from working memory — a phenomenon the scientists called “output gating.”

“In the immediacy of what we’re doing we have this small working memory capacity where we can hang on to a few things that are going to be useful in a few moments, and that’s where output gating is crucial,” said study senior author David Badre, professor of cognitive, linguistic, and psychological sciences at Brown.

From the perspective of cognition, said lead author and postdoctoral scholar Christopher Chatham, input gating — choosing what goes into working memory — and output gating allow people to maintain a course of action (e.g., finish that Bluetooth call) while being flexible enough to account for context in planning what’s next.

Of cognition and wingdings

In their experiments Badre, Chatham, and co-author Michael Frank, associate professor of cognitive, linguistic, and psychological sciences, provided their volunteers with four different versions of a similar working memory task. The versions distinguished output gating from input gating so that the anatomical action observed in the MRI could reliably associate with output gating behavior.

In each round, volunteers saw a sequence of characters — either letters of the alphabet or wingdings (typographical symbols like stars and snowflakes). Before or after the sequence, the volunteers were also given a context cue in the form of a numeral that told them which kind of character would be relevant at end of the task (e.g., “1” might mean a wingding while “2” might mean a letter). The last step for volunteers was to select between groups of characters on the screen that included whichever contextually relevant character they had seen in the sequence (e.g., if the subject had seen a “1” and later a snowflake during the sequence, they should select the group that included a snowflake).

When the context numeral came first, say a “2,” volunteers would “input gate” only letters into their working memory. When it came time to make a selection, they’d simply “output gate” the correct letter from the letters in working memory. If the context came last, people would have to input gate everything they saw into working memory, making all the real thinking a matter of output gating. If the context cue came last, they would carry a higher load of characters in working memory. To address this disparity, the experimenters created two more conditions in which a global context indicator, “3,” required people to keep everything they saw in working memory whether it came before the sequence or after.

With this experimental design the researchers could measure performance and monitor brain activity with subjects who had distinct moments of input and output gating, regardless of the character load in working memory.

People accomplished the tasks with a range of speeds, which the researchers regarded as a proxy for the amount of cognitive work volunteers had to do. People were slowest in making a selection when they got the context cue last and then had to gate just one specific symbol out of memory (e.g., they saw the sequence, then saw a 1, and then had to choose the option with a wingding they had seen). People were fastest at making a selection when they were given the context first and then had to pick the one character of that kind that they saw (e.g., they saw a “2,” then the sequence in which only letters mattered, and then had to choose the option with a letter they had seen).

In analyzing the results, Chatham and his co-authors found that the caudate and the dorsal anterior premotor cortex, contributed distinctly to the reaction times they saw. These separate roles in the partnership agree with computational models of how the brain works.

“The division of labor that’s specifically posited by these computational models is one in which there is a basically a context being represented in the prefrontal cortex that determines the overall efficiency of going from stimulus to response – like a route,” Chatham said. “The striatum is involved in the actual gating of that flow of information,” he said, “like traffic lights along the route.”

So the cortex interprets the context, while the striatum implements the gating. When the context is unhelpfully general and the gating is very specific, for example, the task takes a lot of time.

The findings help advance studies of how cognition works in the brain and could help psychiatrists analyze behavior in people where those areas of the brain have been injured, the researchers said. It also highlights how similar brain circuits can execute different functions – motion and working memory gating.

The brain’s RAM: Rats, like humans, have a “working memory”

Thousands of times a day, the brain stores sensory information for very short periods of time in a working memory, to be able to use it later. A research study carried out with the collaboration of SISSA has shown, for the first time, that this function also exists in the brain of rodents, a finding that sheds light on the evolutionary origins of this cognitive mechanism.

In computers it’s called “RAM”, but the mechanism is conceptually similar to what scientists call a “working memory” in the brain of humans and primates: when we interact with the environment our senses gather information that a temporary memory system keeps fresh and readily accessible for a few minutes, so that the body can carry out operations (for example, an action). For the first time, a research team coordinated by Mathew Diamond of the International School for Advanced Studies (SISSA) in Trieste has shown that this memory system also exists in simpler mammals like rodents.

Working memory has been studied in detail in humans and primates, but little was known about its existence in other animals. “Knowing that a working memory also exists in the brain of evolutionarily simpler organisms helps us to understand the origins of this important cognitive mechanism”, explains Diamond. “Comparative psychology studies have historically helped scientists not only to trace the evolutionary roots of human brain functions but also to gain deeper insight into human cognitive processes themselves”.

The type of sensory memory studied by Diamond and co-workers in rats is tactile memory. The performance of rodents in tasks assessing recognition of vibratory stimuli was compared with that of humans performing similar tasks (rats used their whiskers and humans their fingertips). “Rats exhibited similar behaviour patterns to humans, demonstrating that these animals use a tactile working memory that enables them to recognise and interact with environmental stimuli”. The research paper has been published in The Proceedings of the National Academy of Sciences (PNAS).

More in detail…

“Working memory is an extraordinary cognitive mechanism”, comments Diamond. “It’s like a container where the brain stores little bits of very recent experience, to be able to assess the best course of action. Without this temporary memory, experience would slip away without any chance of being used”.

“Working memory can hold only a limited amount of information for a fairly short period of time. These limits are the result of a cost-benefit balance: the brain’s computational capacity is fixed and decisions as to what action to take often need to be quick and effective as the same time. Our working memory’s capacity is therefore the best we can achieve in terms of accuracy and speed with our brain”.

“The brain regions responsible for working memory have not yet been identified in rats. Some believe that rats don’t have the brain centres known as “prefrontal cortex” which are involved in this function in primates”, continues Diamond. ”Our surprise was to discover that rodents realize memory in a manner similar to humans. Now we are continuing our studies to understand how these mechanisms work in detail”.

Motor Excitability predicts Working Memory

Humans with a high motor excitability have a better working memory than humans with a low excitability. This was shown in a study conducted by scientists from the Transfacultary Research Platform at the University of Basel. By measuring the motor excitability, conclusions can be drawn as to the general cortical excitability – as well as to cognitive performance.

Working memory allows the temporary storage of information such as memorizing a phone number for a short period of time. Studies in animals have shown that working memory processes among others depend on the excitability of neurons in the prefrontal cortex. Moreover, there is evidence that motor neuronal excitability might be related to the neuronal excitability of other cortical regions. Researchers from the Psychiatric University Clinics (UPK Basel) and the Faculty of Psychology in Basel have now studied if the excitability of the motor cortex correlates with working memory performance– results were positive.

«The motor cortical excitability can be easily studied with transcranial magnetic stimulation», says Nathalie Schicktanz, doctoral student and first author of the study. During this procedure, electromagnetic impulses with increasing intensity are applied over the motor cortex. For subjects with high motor excitability already weak impulses are sufficient to trigger certain muscles – such as those of the hand – to show a visible twitch.

Conclusions for other cortical regions
In the present study, that included 188 healthy young subjects, the scientists were able to show that subjects with a high motor excitability had increased working memory performance as compared to subjects with a low excitability. «By measuring the excitability of the motor cortex, conclusions can be drawn as to the excitability of other cortical areas», says Schicktanz.

«The findings help us to understand the importance of neuronal excitability for cognitive processes in humans», adds Dr. Kyrill Schwegler, co-author of the study. The results might also have important clinical implications, as working memory deficits are a component of many neuropsychiatric disorders, such as schizophrenia or attention deficit hyperactivity disorder. In a next step, the scientists plan to study the relation between neuronal excitability and memory on a molecular level.

The study is part of a project lead by Prof. Dominique de Quervain and Prof. Andreas Papassotiropoulos. The project uses transcranial magnetic stimulation to study the cognitive functions in humans. The goal is to identify the neurobiological and molecular mechanisms of human memory.