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‘Sticky synapses’ can impair new memories by holding on to old ones

A team of UBC neuroscientists has found that synapses that are too strong or ‘sticky’ can actually hinder our capacity to learn new things.

University of British Columbia researchers have discovered that so-called “sticky synapses” in the brain can impair new learning by excessively hard-wiring old memories and inhibiting our ability to adapt to our changing environment.

Memories are formed by strong synaptic connections between nerve cells. Now a team of UBC neuroscientists has found that synapses that are too strong or “sticky” can actually hinder our capacity to learn new things by affecting cognitive flexibility, the ability to modify our behaviours to adjust to circumstances that are similar, but not identical, to previous experiences.

“We tend to think that strong retention of memories is always a good thing,” says Fergil Mills, UBC PhD candidate and the study’s first author. “But our study shows that cognitive flexibility involves actively weakening old memory traces. In certain situations, you have to be able to ‘forget’ to learn.”

The study, published today in the Proceedings of the National Academy of Sciences, shows that mice with excessive beta-catenin – a protein that is part of the “molecular glue” that holds synapses together – can learn a task just as well as normal mice, but lacked the mental dexterity to adapt if the task was altered.

“Increased levels of beta-catenin have previously been reported in disorders such as Alzheimer’s disease and Huntington’s disease, and, intriguingly, patients with these diseases have been shown to have deficits in cognitive flexibility similar to those we observed in this study,” says Shernaz Bamji, an associate professor in UBC’s Dept. of Cellular and Physiological Sciences.

“Now, we see that changes in beta-catenin levels can dramatically affect learning and memory, and may indeed play a role in the cognitive deficits associated with these diseases,” she adds. “This opens up many exciting new avenues for research into these diseases and potential therapeutic approaches.”

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Feelings of Failure, Not Violent Content, Foster Aggression in Video Gamers

The disturbing imagery or violent storylines of videos games like World of Warcraft or Grand Theft Auto are often accused of fostering feelings of aggression in players. But a new study shows hostile behavior is linked to gamers’ experiences of failure and frustration during play—not to a game’s violent content.

The study is the first to look at the player’s psychological experience with video games instead of focusing solely on its content. Researchers found that failure to master a game and its controls led to frustration and aggression, regardless of whether the game was violent or not. The findings of the study were published online in the March edition of the Journal of Personality and Social Psychology.

“Any player who has thrown down a remote control after losing an electronic game can relate to the intense feelings or anger failure can cause,” explains lead author Andrew Przybylski, a researcher at the Oxford Internet Institute at Oxford University, who said such frustration is commonly known among gamers as “rage-quitting.”

Running, Cardio Activities in Young Adulthood May Preserve Thinking Skills in Middle Age

Young adults who run or participate in other cardio fitness activities may preserve their memory and thinking skills in middle age, according to a new study published in the April 2, 2014, online issue of Neurology®, the medical journal of the American Academy of Neurology. Middle age was defined as ages 43 to 55.

“Many studies show the benefits to the brain of good heart health,” said study author David R. Jacobs, Jr, PhD, with the University of Minnesota in Minneapolis. “This is one more important study that should remind young adults of the brain health benefits of cardio fitness activities such as running, swimming, biking or cardio fitness classes.”

Cardiorespiratory fitness is a measure of how well your body transports oxygen to your muscles, and how well your muscles are able to absorb the oxygen during exercise.

For the study, 2,747 healthy people with an average age of 25 underwent treadmill tests the first year of the study and then again 20 years later. Cognitive tests taken 25 years after the start of the study measured verbal memory, psychomotor speed (the relationship between thinking skills and physical movement) and executive function.

For the treadmill test, which was similar to a cardiovascular stress test, participants walked or ran as the speed and incline increased until they could not continue or had symptoms such as shortness of breath. At the first test, participants lasted an average of 10 minutes on the treadmill. Twenty years later, that number decreased by an average of 2.9 minutes. For every additional minute people completed on the treadmill at the first test, they recalled 0.12 more words correctly on the memory test of 15 words and correctly replaced 0.92 more numbers with meaningless symbols in the test of psychomotor speed 25 years later, even after adjusting for other factors such as smoking, diabetes and high cholesterol.

People who had smaller decreases in their time completed on the treadmill test 20 years later were more likely to perform better on the executive function test than those who had bigger decreases. Specifically, they were better able to correctly state ink color (for example, for the word “yellow” written in green ink, the correct answer was “green”).

“These changes were significant, and while they may be modest, they were larger than the effect from one year of aging,” Jacobs said. “Other studies in older individuals have shown that these tests are among the strongest predictors of developing dementia in the future. One study showed that every additional word remembered on the memory test was associated with an 18-percent decrease in the risk of developing dementia after 10 years.”