Do you ever feel like sometimes you can master a new dance step almost immediately, while other times you struggle to nail it despite repeated practice? This might be due to skill or effort, but also to something less obvious: whether the brain is in a state that allows learning to take hold.

The brain does not learn in isolation from the rest of the body. Signals from internal organs continuously reach the brain through a key part of our nervous system called the vagus nerve. Researchers at Tohoku University specializing in super-network brain physiology have now demonstrated in mice that stimulating this nerve after training can promote lasting motor learning. This study reveals a previously underappreciated way in which body-to-brain signaling may support long-term learning.

The findings were published in iScience on August 25, 2026.

The vagus nerve is a major communication route between the body and brain, carrying information from internal organs to the brain and signals from the brain back to internal organs. This pathway can be modulated through vagus nerve stimulation (VNS), a clinically approved treatment for several disorders. Previous studies have investigated VNS as a neuromodulation technique that alters neurotransmitter systems, but this new study reveals another possible mechanism behind VNS: rhythmic changes in brain blood vessels.

The researchers developed a small cuff electrode that could remain attached to the left cervical vagus nerve of mice. They then examined VNS during horizontal optokinetic response (HOKR) learning, a cerebellum-dependent eye-movement task in which mice learn to track moving visual stripes more effectively. The response resembles the reflexive eye movements you make when standing on a platform and watching a train pass by.

VNS was delivered after each training session. It did not improve performance during training itself; instead, its effects emerged later. Mice receiving VNS showed stronger long-term learning on subsequent days, suggesting that stimulation acts on post-training processes supporting memory consolidation.

"The key point is that VNS was delivered only after training," says Professor Ko Matsui. "Our findings suggest that VNS may open a hidden window of opportunity for enhanced learning by making the brain environment more receptive to long-lasting change."

To explore the accompanying brain changes, the team measured blood-volume dynamics near the cerebellar flocculus, a region involved in HOKR learning. Fiber photometry revealed that a single VNS train produced a biphasic vascular response: a brief decrease in local blood volume followed by a delayed increase. Repeated VNS induced rhythmic blood-volume oscillations, and mice with larger oscillations tended to show better learning on Day 5.

"Our brains may be more strongly influenced by the body than we imagine," says lead author Junyu Chen. "By tuning the brain's metabolic environment, including rhythmic vascular movements, we may eventually unlock capacities that would otherwise remain latent."

Future studies will aim to optimize stimulation protocols in order to further clarify how the brain-body axis supports long-term plasticity. Studying this two-way route between the brain and the body will help us better understand the details of learning - and how we can facilitate it.