It is well established that myelin – a protective layer that forms around the nerve fibers – is important for effective brain connectivity. Now, researchers from University College London in the UK claim the substance is crucial for learning new practical skills, such as playing a musical instrument, but it is not necessary for retaining the information.
The research team, led by Prof. Bill Richardson, director of the Wolfston Institute for Biomedical Research at the university, publish their findings in the journal Science.
Myelin is a fatty material that forms a part of the white matter in the central nervous system. Produced by the brain and spinal cord up until early adulthood, myelin acts as an insulator for nerve fibers, protecting them from damage and enabling them to quickly and efficiently transmit signals between nerve cells.
The research team says past studies have suggested that myelin is important for learning new skills, but theirs is the first study to confirm this through experiments.
The researchers explain that effective skill learning requires new, high-speed electrical signaling between neurons that are connected by axons, which the researchers refer to as the “wires” in the electric circuit. Repetition of the new signaling along the axons boosts connections between the neurons, meaning the neurons find it easier to remember the signaling pattern the next time it is required.
Oligodendrocytes (OLs) – cells located next to the neurons that produce myelin – can recognize this repeat signaling. They then produce myelin and wrap it around the newly-activated circuit. The team’s study shows that this process is vital for learning a practical skill.
To reach their findings, Prof. Richardson and his team analyzed 32 mice that were treated with a drug that halted the development of OLs. These mice were compared with 36 normal mice.
The researchers monitored the ability of both groups of mice to learn how to run on a complex wheel that had ladders, or rungs, with irregular spacing.
They found that after 2 hours, the normal mice were able to learn how to run the wheel effectively. However, the mice that were prevented from producing myelin were unable to learn how to run the wheel.
“We were surprised how quickly we saw differences in the ability of mice from each group to learn how to run on the complex wheel, which shows just how fast the brain can respond to wrap newly-activated circuits in myelin and how this improves learning,” says Prof. Richardson, adding:
“This rapid response suggests that a number of alternative axon pathways might already exist in the brain that could be used to drive a particular sequence of movements, but it quickly works out which of those circuits is most efficient and both selects and protects its chosen route with myelin.”
In another experiment, the team treated mice with the OL-blocking drug after they had learnt how to run the complex wheel. On re-introducing these mice to the wheel, the researchers found they were able to run the wheel as they did prior to being treated with the drug, indicating that the inability to produce new myelin does not hinder the ability to recall and perform tasks.
Prof. Richardson says the team’s findings are “really exciting,” noting that they could lead to new ways to boost skill learning and pave the way for assessing how OLs and myelin play a part in other brain processes, such as cognitive function.
“I’m keen to find out the precise sequence of changes to OLs and myelin during learning and whether these changes are needed more in some parts of the brain than others,” he adds, “which might shed light on some of the mysteries still surrounding how the brain adapts and learns throughout life.”
In August, Medical News Today reported on a study claiming memories of error improve learning speed.