Brain stimulation improves motor skill learning at older age

Even though we don’t think about it, every movement we make in our daily life essentially consists of a sequence of smaller actions in a specific order. The only time we realize this is when we have to learn a new motor skill, like a sport, a musical instrument, a new dance routine or even a new electronic device such as a smart phone or videogame controller.

Perhaps unsurprisingly, there is a lot of research invested in figuring out how humans acquire sequential motor skills, with a majority of studies in healthy young adults. Studies involving older individuals (and common experience) show that the older we get, the harder it is and the longer it takes to learn new motor skills, suggesting an age-related decrease in learning ability.

“As learning is crucial for continuously adapting and staying integrated in daily life, improving these impaired functions will help to maintain the quality of life as we age, especially in view of the constant increase in life expectancy seen worldwide,” says Professor Friedhelm Hummel who holds the Defitech Chair of Clinical Neuroengineering at EPFL’s School of Life Sciences.

In a new study, Hummel and his PhD student Pablo Maceira-Elvira have found that transcranial brain stimulation can improve the age-related impairment in learning new motor skills.

The study used a common way of evaluating how well a person learns new motor skills called the “finger-tapping task.” It involves typing a sequence of numbers as fast and as accurately as possible. The task is popular in studies because it simulates activities that require high dexterity — such as playing the piano or typing on a keyboard — while providing an objective measure of “improvement,” defined as a person increasing their speed without losing accuracy.

Scientists refer to this as a “shift in the speed-accuracy tradeoff,” and it constitutes a key feature of learning. One of the ways the brain achieves this shift is by grouping individual motor actions into so called “motor chunks”: spontaneously emerging brain structures that reduce a person’s mental load, while optimizing the mechanical execution of the motor sequence. “Motor chunks emerge reliably when young adults train on the finger-tapping task, but previous studies show either lacking or deficient motor chunks in older adults,” says Pablo Maceira-Elvira.

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