A Brief Introduction to Brain-Computer Interfaces

Image of the Neuralink Implant

If you’ve been paying any attention to technological developments lately, you’ve probably heard of Neuralink. If you haven’t, Neuralink is a brain-computer interface company founded by Elon Musk focused on bringing powerful brain-computer interface technology to the masses. Neuralink is special in that it pairs together a small, powerful implant that interprets brain activity and a simple yet super-precise robotic surgery method for inserting neural threads into one’s brain for an extremely effective brain-computer interface. They claim that such an implant can one day be used to help people with paralysis and allow people to control their devices simply with their thoughts. Now, you might be wondering, what even is a brain-computer interface?

What is a brain-computer interface?

In short, a brain-computer interface (BCI) is a device that can read and interpret the neural signals sent out by our brain to perform a variety of tasks. To better grasp how this can be done, we first need to gain an understanding of how our brains work.

Basic diagram of a neuron

Our brain consists of nearly 85 billion neurons, also known as nerve cells. These nerve cells are made up of 5 main parts: dendrites, the soma, the axon hillock, the axon, and synaptic buttons. Whenever we perform any action in our body, the process to do so begins in our neurons, with the signal moving through our central nervous system (CNS) to its end destination. It starts as a chemical signal that interacts with the dendrites in our neurons, producing an electrical signal. This signal is then sent into the soma, or the cell body, which interprets it and places the information into the axon hillock. Here, if the signal is strong enough, it will then proceed into the next part of the neuron, the axon. At this point in the process, the signal is called an action potential, which travels down the axon (covered in myelin, an insulative material that prevents signal degradation). The signal enters the axon terminals, also known as the synaptic buttons, where new neurotransmitters may be released. This portion of the neuron is connected to the dendrites of other neurons and the process repeats until the signal reaches its destination, where it becomes an action, thought, or feeling.

Think of it like sending mail internationally. At the post office, you address and send your mail, the signal, which is then sent to another post office closer to your destination, another neuron. There, the address is interpreted and sent to another post office, likely one that is in the country to which it is addressed. The address is once again interpreted here and sent to the post office closest to the recipient. The mailman, another neuron, would then deliver this mail to the end recipient, who will then open the mail. We can consider the opening of the mail analogous to an action being performed from the transmission of neural signals throughout our central nervous system.

Now that you understand how our nervous system works, you’re probably wondering how BCIs come into the picture? Well, BCIs measure this neural activity and interpret it, measuring the neural activity that stems from various actions and mapping these to different actions in the real world. An example would be measuring the neural activity from clenching your jaw and mapping that to increase the volume on your phone, or mapping your blinking to be used as a select button on a device. To better understand this, it’s better to jump right into one of the most popular methods used for measuring neural activity, electroencephalography.

Okay, so what is electroencephalography?

Electroencephalography, also known as an EEG, is a non-invasive technique usually performed by placing electrodes on the scalp to record the electrical activity in one’s cerebral cortex. EEGs do not record the activity of individual neurons, but rather the signals from large groups of neurons that are active all at once. It records activity from the small areas of the brain surrounding the electrodes, primarily measuring postsynaptic potentials, which are not action potentials, but rather the signals emitted after the action potential has already fired.

Sample graphic of EEG electrodes and an EEG reading

These measurements can be used to create a picture of electrical activity in the brain, which can be shown as waves of varying frequencies, amplitudes, and shape. EEGs measure brain activity that occurs during an event, or spontaneous brain activity. This activity that occurs in association with an event is called event-related potential. Events such as blinking or clenching one’s jaw can easily be recorded on an EEG. Some of the most common clinical applications of EEGs include but are not limited to characterizing seizure activity, diagnosing epilepsy, or monitoring the brain to gain information about a variety of other brain dysfunctions.

Although they lack in pinpointing where the activity occurs on the brain and cannot accurately record activity from structures deeper than the cortex, EEGs are popular amongst researchers because of their relatively low cost and the ability to measure brain activity on the order of milliseconds. This lack of spatial resolution makes it difficult in developing complex EEG-based BCIs though, as you can only perform so many neural activity-intensive actions for various tasks. At some point, you would want to just think of an action and have it performed, without the need for an unnecessary event like blinking. This is where electrocorticography comes in.

Wait, electrocorticography?

Yup. You heard that correctly. Electrocorticography, also known as ECoG, is an invasive neuroimaging method that possesses extremely high spatial and temporal resolution. Through an ECoG, you would be recording neural activity directly from the brain, which can not only be used to precisely map electrical activity throughout the brain but also ensure that intracranial recordings such as blinking do not lower the resolution of the measurements as they usually do with EEGs. The one huge downside to this method is that it is invasive and requires surgery to place into the patient.

ECoG placement relative to an EEG

Alright, I think I get it, but what can BCIs even be used for?

BCIs are already being used to try new methods of treatment for people with certain disabilities or neural diseases. With the versatile nature of this technology, BCIs can be used in several ways to improve the lives of everyone. One such application is being developed at UCLA health using a BCI implanted into the visual cortex of Jason Esterhuizen, who lost his sight in a car accident. In the video shown below, visuals from a video camera are converted into electrical pulses to the brain that restores a basic sense of light and dark back to Jason.

Currently, the company Neuropace is even working towards using BCI technology to help epilepsy patients by preventing seizures before they even occur by detecting unusual electrical activity and delivering electrical pulses to the brain.

BCI company Neurable is developing ways to bring the worlds of augmented reality and BCIs together to control devices simply with your mind, whether this is in the real world or a virtual world. Their software is making strides in taking in EEG data and converting it to user intent, figuring out what you are trying to do.

These are just some of the many possible applications of BCIs that people are already working on, and as this technology continues to gain momentum, novel applications for BCIs will keep emerging. The possibilities are endless, as this technology has the potential to intersect with various other emerging technologies such as artificial intelligence, nanotechnology, or the internet of things (IoT).

Does this mean we will be able to download information directly into our brain like in The Matrix?

Well, maybe. With BCI research growing rapidly, a time in the near future may come when we will be able to download martial arts straight into our heads just like Neo.

In the coming decades, we might live in a world where our thoughts have the power to control everything around us, as the line between science fiction and reality become blurred. Who knows, maybe getting a Neuralink implant will become something as common as buying an iPhone, connecting everyone and the world around them.

Key Takeaways:

  • The human brain is made up of tens of billions of neurons and all of our actions, feelings, and thoughts are a result of chemical and electrical signals that are transmitted between the neurons in our body, throughout our central nervous system (CNS).
  • By measuring and interpreting these electrical signals, we can use brain-computer interfaces to perform a variety of tasks.
  • The most common technique used in measuring neural activity is electroencephalography, which is non-invasive and measures electrical activity from large groups of neurons through electrodes placed on one’s scalp.
  • Electrocorticography can also be used to measure neural activity, being much more spatially accurate than electroencephalography, but also invasive.
  • BCIs have nearly endless applications, being able to interconnect with almost any other modern technology in the world.

Thank you for reading my article! If you have any questions or wish to have a discussion with me on BCIs, feel free to contact me via email (smitbhagat522@gmail.com) or LinkedIn.

Hello! I'm Smit Bhagat, a senior at Warren High School and an innovator interested in brain-computer interfaces at The Knowledge Society LA.