Scientists develop a new brake pedal for the brain

Peter, 29 years old, experiences epileptic seizures several times a week. They strike out of the blue. An electrical storm disables his brain. The medications meant to reduce the excessive electrical activity do not work. Nor do surgical options. Peter therefore rarely leaves home and is increasingly wasting away inside his apartment.

But now there is hope for Peter.

In a new study, a team led by Danish researchers has developed a method in which tiny magnetic coils generate electric fields that can precisely dampen activity in nearby nerve cells.

This is a breakthrough that, until recently, was considered impossible. So far, all attempts at stimulating brain tissue have only increased activity. The neurons went into overdrive.

“Imagine if you only had an accelerator before but now you also have a brake. It opens up an entirely new world,” says Anpan Han, Senior Researcher at the Department of Civil and Mechanical Engineering of the Technical University of Denmark. He just published the study in the respected journal Advanced Science alongside an international team of researchers from Harvard Medical School, Yale School of Medicine, the University of Copenhagen and other universities.

Anpan Han is confident that the discovery could lead to new treatments – potentially curing people with epilepsy and other conditions characterised by excessive activity in specific brain regions.

Until now, doctors have only been able to reduce brain activity indirectly and imprecisely. Now, for the first time, there is a real brake that directly inhibits neurons.

“If your car only has an accelerator, the best you can do is lift your foot and hope it slows down. This is imprecise and hard to control. That is how we used to see the brain – as something we could activate but not really calm down. But it turns out that the brain actually has a built-in braking system. And now we have found a way to engage it,” he says.

The invention worked in a way no one expected

The discovery came as a surprise. Anpan Han and his colleagues at the Technical University of Denmark had spent years developing magnetic microcoils – tiny components that can be placed directly in the brain to influence nerve cells using electric fields. The idea was to develop a new way to activate brain cells – a softer, more precise form of stimulation than existing electrodes provide.

Unlike traditional electrodes, which deliver direct current straight into brain tissue and drive neurons to fire, these microcoils use alternating current – constantly switching direction – to generate an electric field. The field spreads more gently and diffusely through the tissue.

But when they tested the coils in live mouse brains, something unexpected happened. Instead of revving up the neurons, the coils calmed them down. Rather than being activated, the cells were inhibited.

“This was a huge surprise,” says Anpan Han. “We thought we had built a new kind of accelerator. But it turned out to be a brake.”

To understand what was going on, the researchers had to examine intact brain tissue. Petri dish cell cultures were not enough – they only contain isolated cells. Human brains were out of the question, both ethically and practically. Mouse brains, however, enabled the team to track how signals move through layers of tissue and between different types of neurons.

Using advanced microscopy and image analysis, they observed the cells’ responses in real time. The more they looked, the clearer it became: the electric field from the coil was dampening brain activity with precision – targeting an area just one seventh the size affected by conventional electrodes.

The battle for an idea

Once the team realised that they had discovered something new – maybe even groundbreaking – the real work began. Not in the laboratory but in the legal and strategic backroom, where scientific ideas are turned into protected technologies. Anpan Han and his collaborators filed a patent application. For more than a year, they worked quietly to refine the system and collect data. They built collaborations to help to mature the discovery into a practical foundation for future breakthroughs.

“We could not say anything publicly,” Anpan Han explains. “We had to protect the idea until the patent was in place. Now it is, and that gives us the freedom to move forward – and perhaps, in time, others will benefit from it too.”

This field is competitive. Research groups around the world are racing to develop alternative neuromodulation methods using magnetic fields – hoping to avoid the side-effects and blunt effects of traditional electrodes.

Some, especially in the United States and Asia, are pursuing transcranial magnetic stimulation, which uses large external coils to stimulate the brain from the outside. But this struggles to reach deep brain structures with precision. The new microcoil is implantable and works exactly where it is placed – with high accuracy and fewer side-effects. What makes the Danish project unique is how it combines microscopic scale, implantability and inhibitory function into one system.

That is why this is not just a race to understand the brain – but to deliver technologies that doctors and patients can actually use.

A breakthrough for brain treatment

Epilepsy is an obvious first target. As many as one in three people with epilepsy do not respond to medication, and surgical alternatives are invasive and risky. An implantable brake that can stop seizures at their source – without damaging the surrounding brain areas – would be a game-changer. In mouse experiments, the new method already reduced seizure strength by more than 50%. For Peter, this opens a door – a chance to be part of the world again.

But epilepsy is only one piece of the puzzle.

Chronic pain, which often stems from long-term overactivation of nerve pathways, could also be addressed. The same goes for tinnitus, in which faulty signals in the brain’s auditory cortex create a constant, disruptive perception of sound.

And in cases such as overeating or arrhythmia, carefully targeting hyperactive brain regions could offer a side-effect-free alternative to current medications, which affect the entire body.

Today, researchers are collaborating with clinicians and technology partners to decide where to apply the method first. A spin-out company is now preparing to bring the microcoil out of the laboratory and into clinical practice.

The need is enormous. Most neurological and mental disorders boil down to disruptions in the brain’s electrical balance.

“This discovery gives us real hope for future treatments that work by harnessing the brain’s own way of regulating itself,” says Anpan Han.