Nerve stimulation after practice could help new skills stick

Stimulating the vagus nerve after practising a new skill could help the brain remember it for longer, according to research from Tohoku University in Japan.

The study, carried out in mice, found that stimulation delivered after training sessions, rather than during them, strengthened long-term retention of a motor skill. The results are published in the journal iScience.

The vagus nerve

The vagus nerve is the longest of the cranial nerves. It runs from the brainstem through the neck to the chest and abdomen, carrying signals between the brain and organs including the heart, lungs and gut. It plays a central part in controlling heart rate, digestion and other functions that happen without conscious thought.

Vagus nerve stimulation, using small electrical pulses, is already used as a medical treatment for some people with epilepsy and depression that have not responded to other treatments. Researchers have also been testing it to help stroke patients recover movement.

What the study did

The researchers fitted mice with small electrode cuffs around the vagus nerve. The animals were trained on a task in which their eyes learned to follow a moving visual pattern, a kind of learning that depends on the cerebellum, the part of the brain at the back of the head that co-ordinates movement.

When stimulation was applied after training, the mice retained what they had learned better over the following days.

A role for blood flow

The team found that stimulation produced rhythmic changes in the volume of blood in a part of the cerebellum called the flocculus. Mice with larger blood volume oscillations showed better learning by the fifth day.

The researchers suggest that stimulation during the period when memories are being consolidated "may open a hidden window of opportunity for enhanced learning by making the brain environment more receptive to long-lasting change".

"Our brains may be more strongly influenced by the body than we imagine," they said.

Who did the research

The work was led by Junyu Chen, with Yoko Ikoma and Ko Matsui at Tohoku University.

A note of caution

The study was carried out in mice, and it is not yet known whether the same effect would happen in people. More research will be needed to work out the right timing and strength of stimulation before it could be tested in humans.

People should not try to stimulate their own vagus nerve using devices bought online, which are not a substitute for medical treatment.

Why it matters

If the findings are confirmed in humans, they could help with rehabilitation after strokes and brain injuries, where patients need to relearn movements, as well as with learning new physical skills such as playing an instrument or a sport.

The findings add to a growing body of research showing how closely the body and brain are linked, from the gut to the heart, and how signals from the body can shape how we think, feel and learn.

The science of sleep and memory

Scientists already know that much of the consolidation of new memories happens after practice, including during sleep. That is one reason why spacing out practice sessions and getting a good night's sleep can help people learn new skills more effectively than cramming.