Inside the Science: Brain-Computer Interface and ALS

A brain-computer interface (BCI) is a system that allows direct communication between the brain and an external device, such as a computer. BCI studies often include participants living with ALS, as the technology holds promise for people affected by paralysis. The two main areas of BCI research in ALS are focused on communication assistance and functional independence. Functional independence focuses on movement restoration, such as controlling a computer or smartphone, and potentially even assistive devices in the future, such as wheelchairs, robotic arms, smart home systems, etc., ultimately improving the quality of life for people affected by ALS.  

Although an exciting avenue of research, BCIs are still being thoroughly explored. Researchers are working to fully understand the safety and efficacy of these devices, especially long-term before they can be made widely accessible to the general population.

How does a BCI work?  

Brain-computer interfaces work by detecting small electrical charges when our brain cells are activated. A BCI can detect these signals using devices called electrodes when they are placed on the scalp (non-invasive) or implanted in the brain (invasive). An individual’s neuronal activity is then collected and interpreted, as different actions or intentions will have different electrical signatures in the brain. The BCI collects and learns to interpret what each electrical signature means. This interpretation is usually highly individualized as this electrical activity can vary slightly from person to person, so a training period after implantation is needed. Importantly, a BCI cannot read thoughts — by using the participant’s feedback, the technology is trained to associate a specific signal in the brain with the original intention or action that the participant wanted to convey.  

The concept of a direct interface between the brain and a computer was first explored in the 1970s, using electroencephalography (EEG), non-invasive electrodes placed on the scalp. This method is easier to set up and has fewer side effects; however, it provides lower accuracy as brain signals captured are weaker. 

It was only in the early 2000s that implantable BCI became a more popular area of research. An invasive BCI is implanted directly in the brain, providing more precise readings, but requiring a small surgery. It is usually placed in an area of the brain that the BCI is trying to target – for example, if the technology is aimed at restoring movement, it would be placed in a part of the brain responsible for movement, such as the motor cortex. An implantable BCI can be wireless or require external wires connected to the interface to transmit data, which could limit mobility and convenience and may increase adverse reactions. Because of their higher accuracy, invasive BCIs are more popular in ALS research, although non-invasive BCIs also exist in the field.  

BCI research in ALS 

Communication assistance in ALS 

Since the 2000s, researchers have made significant progress in using a brain-computer interface for communication assistance. Dr. Nick Ramsey, from the University Medical Center Utrecht, has been working with BCI technology since 2005. In a 2016 study led by Dr. Ramsay and his team, a participant living with ALS using a BCI was able to type words by selecting letters on the screen, at the rate of two letters per minute. At the time, the BCI did not associate electrical signatures with words – but rather allowed the participant to select commands on a tablet, working towards restoring communication this way. You can see Dr. Ramsey presenting his work during ALS Canada’s Virtual Research Forum, in 2018. 

Other current BCI studies are also working toward communication assistance via typing. Recently, however, an exciting advancement in speech facilitation has been made by BrainGate, a research consortium studying BCI technology in ALS for close to 20 years. 

Their recent study at the University of California, Davis, investigated the use of a BCI in facilitating communication for a 45-year-old man living with ALS. In the study, the participant could no longer speak after five years of disease onset, but by implanting the BCI in an area of the brain responsible for speech production, researchers were able to directly decode the participant’s brain signals as they tried to form words – no typing necessary. These decoded words were displayed on a computer screen and vocalized through a text-to-speech system.  

Over the years, the primary challenges for BCIs have been the high level of training required and the limitations in accuracy and speed. The results of this study also showed promise in addressing these limitations: the calibration process, which involves recording brain signals while the participant attempted to speak, took just 30 minutes. Additionally, on the first day of testing, 25 days after the surgery, the technology achieved a 99.6% accuracy in translating his brain activity into text, although with a limited vocabulary of 50 words. Over the next 8.4 months, the system maintained an accuracy of 97.5%, allowing the participant to engage in conversations at a speed of 32 words per minute, within a 125,000-word vocabulary. You can see a video of the participant communicating with his family here. 

At the 2024 International Symposium on ALS/MND, the annual Sean M. Healey International Prize for Innovation in ALS was awarded to Dr. Leigh Hochberg and the team behind the BrainGate Consortium.  

Maintaining independence in ALS 

BCI research has also progressed in helping people living with ALS to control external devices. Recent work in the area includes a wireless BCI called Stentrode, by Synchron. Stentrode targets the motor cortex, the area of the brain responsible for movement, and can be implanted through a blood vessel in the neck, bypassing the need for brain surgery.  

Its SWITCH study, completed in 2022, investigated the technology in four participants (living with ALS and PLS), studying the safety and efficacy of both the BCI alone and the BCI combined with eye tracking (ET). Participants were able to control the system with a mean selection accuracy of 93.9%, performing tasks like emailing, texting, and browsing the internet. The typing average reached 16.6 characters per minute, with 97.2% of the text typed being correct. The participant using only the brain-computer interface was able to successfully send text messages and make selections (out of five options) with a mean accuracy of 97.4%. No serious side effects were reported over a year, which holds promise for further studies exploring the technology and its efficacy.  

Additionally, another company called Neuralink is currently conducting a Phase 1 study (PRIME) to investigate the safety of their wireless BCI (N1) in helping people with paralysis control external devices. Their implant combines existing BCI technologies into a single device: it targets individual motor neurons (the brain cells responsible for voluntary movement control) and can wirelessly recharge and transmit data. A surgical robot does the BCI placement, and it is also made of thinner, more flexible material, potentially reducing the risk of inflammation or scarring. Although the interface could be promising, it is still in the very early stages, and research needs to be conducted to assess its safety and efficacy.

What does the future of BCI research look like? 

Although promising, researchers still need to evaluate the safety and functionality of different brain-computer interface technologies. The field still needs continued research and refinement, and it may still be years before a BCI can become a standard method for restoring communication and movement, compared to traditional assistive technologies that use eye movements or muscle control. Improving the technology for faster and more accurate readings is also a major focus point.   

Another potential limitation of the technology is longevity, as it has not been extensively examined in people living with ALS. A recent study  indicated that the accuracy of a BCI may decline over time as the disease progresses, which could be a limitation of these interfaces. Future research may need to investigate brain regions less prone to degeneration or more likely to be affected by disease progression.   

Like in all research, communication about these interfaces should be approached thoughtfully, with studies being conducted in a safe and transparent manner. Due to the excitement that a BCI holds over improving the quality of life for people living with ALS, companies and researchers need to ensure that study results and information about these technologies are clear and accessible.  

Inside the Science 

In our blog series, Inside the Science, we break down and discuss trending topics in ALS research, making complex science accessible to anyone affected by ALS.