Kawahara

Today we have three researchers who are working on the research and development of minimally invasive BMI as part of the Internet of Brains (IoB) project. It’s a pleasure to meet you all. Thank you for joining us.

Yanagisawa
Sekitani
Nakamura

 
Nice to meet you, too.

Kawahara

Is this the first time the three of you have collaborated on a project?

Yanagisawa

Yes. Dr. Nakamura and I were both in the same neurosurgery department at Osaka University, and I have known Dr. Sekitani for some time, but this is our first time collaborating closely.

<strong><span style="font-size: 15pt; line-height: 23px; font-family: 'Yu Gothic', sans-serif;">Gentle on the Brain, Yet Reaching Deeper</span></strong>

Kawahara

Could you briefly explain what BMI is?

Yanagisawa

BMI (Brain-Machine Interface) is an interface that connects the brain and machines. It allows individuals who are unable to move to type or control avatars using brain signals, it can also enable people who have lost sensory perception to regain artificial sensations.

Kawahara

What is minimally invasive BMI?

Yanagisawa

I am currently working with epilepsy patients who have implanted electrodes for measuring brain waves, using this data to estimate their intentions. When electrodes are implanted directly into the brain (this is called invasive), we can already extract a significant amount of information.

Yanagisawa

However, this requires a craniotomy (a surgical procedure to open a part of the skull), which carries risks. That’s why we are researching and developing minimally invasive BMI, which allows electrodes to be placed inside blood vessels in the brain without the need for open surgery. This way, we can obtain brainwaves with minimal impact on the brain.

Kawahara

How does the minimally invasive BMI being developed in the IoB project differ from previous research?

Yanagisawa

An American company called Synchron is developing a minimally invasive BMI device called Stentrode. This device can be implanted into a large, rigid blood vessel known as the superior sagittal sinus (SSS), which runs along the top of the brain, between the left and right hemispheres.

Sekitani

However, since Stentrode has a rigid, tubular structure, it has limitations in navigating smaller, more intricate blood vessels.

Yanagisawa

To fully utilize BMI, we need to collect brain signals related to movement, including hand motions or mouth motions for speech. However, these regions of the brain are located far from the SSS.

Sekitani

To reach small blood vessels branching from the SSS, the IoB project is developing a thin, flexible sensor that uses a spiral-shaped film that expands inside the blood vessels.

A one-yen coin and the small measuring device that wraps around a wire

The measuring device magnified under a microscope 

Sekitani

We have designed the film to remain flexible even when integrated with electrodes and other components.

Nakamura

This flexibility allows the device to be delivered through complex blood vessels and reach deep brain structures that would be inaccessible via traditional craniotomy. In the future, this technology could enable us to capture signals from deep brain regions that were previously undetectable.

<strong><span style="font-size: 15pt; line-height: 23px; font-family: 'Yu Gothic', sans-serif;">Integrating Medicine, Engineering, and Information Technology</span></strong>

Kawahara

Could you share us the current status of your research?

Nakamura

We couldn’t start with human trails right away, so we first conducted an experiment using pig models to measure brain activity via blood vessels. As expected, we found that we could obtain more precise EEG signals compared to the SSS. 

Kawahara

How do you insert an electrode into a pig brain?

Nakamura

This is a life-sized model of a pig brain. It’s about 1/3 the size of a human brain, and our target vessels running on the brain surface are extremely small—about 0.8 mm.

Human brain model (top), and pig brain model (bottom)

Nakamura

In the experiment, we first inserted a 3 mm-wide catheter into the pig’s groin (femoral vein) and guided it to the internal jugular vein in the neck. Through this catheter, we inserted a thinner microcatheter and carefully navigated it to the target blood vessel in the brain.
We used X-ray to visualize the target vessels. Under fluoroscopic guidance, we navigated a soft, ultra-thin guidewire with a curved tip into the target vessel, then we advanced the microcatheter along the guidewire. Once the microcatheter reached the desired location, we removed the guidewire and inserted the electrode device via the microcatheter.

（YouTube links）Minimally Invasive BMI Electrode Placement / Wireless Power and Data Transfer System

Yanagisawa

For these experiments, we all travel from Osaka to the Fukushima Medical Development Support Centre in Fukushima Prefecture.

Sekitani

Dr. Nakamura is incredibly skilled at navigating microcatheters through tiny blood vessels that I can’t even see. If he makes even one mistake, the day’s experiment is over, so I imagine the pressure is immense.

Nakamura

I deal with this kind of challenge daily, so I believe I’ve gotten used to it.

Kawahara

So, I see that, thanks to your combined knowledge and skills, minimally invasive BMI is now becoming a reality.

<strong><span style="font-size: 15pt; line-height: 23px; font-family: 'Yu Gothic', sans-serif;">Balancing Safety with Speed</span></strong>

Kawahara

What challenges remain in bringing this technology to society?

Yanagisawa

I think it is important to take one step at a time and make sure that each step is safe. At the same time, there are people waiting for treatment, so it is also important to move the project forward as quickly as possible.

Sekitani

In the future, if the temperature of the device rises significantly as the functions of the device increase, it won’t be possible to place it in the body. I want to take measures to deal with this issue as well.

Nakamura

Blood vessel structures vary from person to person. That’s why device placement should be tailored to each patient’s unique vessel structure, and the device should be guided safely and reliably. We believe that by creating 3D models of individual patients and training with them in advance, we can deliver devices more safely to their destinations.

<strong><span style="font-size: 15pt; line-height: 23px; font-family: 'Yu Gothic', sans-serif;">A New Pathway Opens Up from Blood Vessels</span></strong>

Kawahara

If minimally invasive BMI becomes available in the future, in what situations would you like to see this technology used?

Yanagisawa

Many patients struggle with physical mobility issues, so I think the first step is to use it for motor function restoration. Considerable research has already been accumulated in the field of BMI for motor function.

Sekitani

I want to deepen our understanding of brain function itself. The brain consumes little power yet exhibits remarkably high cognitive abilities. Understanding brain functions will contribute to the development of sustainable electronic devices with lower power consumption. Ultimately, I dream of realizing an artificial brain.

Nakamura

Blood vessels serve as wide-open pathways throughout the body. For example, if our device were used to stimulate the gastrointestinal tract when it isn’t functioning properly, it might help improve its condition. It may sound like science fiction, but as the technology advances, we’ll likely see applications in other organs as well.

<strong><span style="font-size: 15pt; line-height: 23px; font-family: 'Yu Gothic', sans-serif;">Further Collaboration for Social Implementation</span></strong>

Kawahara

Who would you like to work with moving forward?

Yanagisawa

I’m eager to hear from companies not only interested in device manufacturing but also in social implementation and application, as well as researchers and medical professionals.

Sekitani

Since this device directly measures signals from within the brain and body, it’s essential to respect the cultural values of countries and regions. I’d like to collaborate with experts who have that knowledge to ensure compliance with international safety standards.

Nakamura

If you work in the medical field and have an idea you’d like to bring to life, we would love to hear from you.

Writing and Video Editing by Space-Time Inc.