Brain–computer interface

Your brain sends tiny signals.

These signals help you move. Now, computers can read them. This helps people move robot arms.

It can even help people talk. Some tools sit on the skin. Others go inside the head. This helps people who cannot move. It can even help people see or hear. It is like magic! Can you imagine thinking to move a toy?

Your brain is always busy. It sends out tiny electrical signals.

A brain-computer interface, or BCI, links these signals to a device. This device can be a computer or a robot arm.

BCIs help people move or talk. They can even help people see or hear.

There are different ways to use a BCI. Some are active. This means the person must think hard to give a command. They might do math in their head to move a cursor. Other BCIs are passive. These do not need a command. Instead, they watch the brain. They can see if a person is tired or focused.

Some tools sit on the skin. Others are placed closer to the brain. This is called being invasive. Scientists use these tools to study how the brain works. They have even used them with monkeys. Some monkeys used their thoughts to move robot arms.

This research helps us learn how to fix the body.

A brain-computer interface, or BCI, is a direct link between the brain and a device.

This link uses the brain's electrical activity to talk to computers or robotic limbs. Most BCIs aim to help people with sensory or motor functions. They can assist with moving or even help people communicate. These systems often skip the need to move body parts like hands or feet. This makes them very useful for people with severe impairments. Scientists use them to map how the brain works every day.

BCIs work in a few different ways depending on the goal. Active BCIs require a person to consciously change their brain activity. A user might use mental math or focused attention to send a command. This can help someone move a cursor or spell out words.

Passive BCIs are different because they do not need intentional commands. Instead, they monitor brain states like fatigue or alertness all the time. These systems can change how a computer behaves without being told. Reactive BCIs sit in the middle by responding to outside stimuli.

Research into these tools began many years ago. Hans Berger first recorded human brain activity using EEG in 1924.

He used silver wires and later silver foils to find brain waves. Jacques Vidal is known as the inventor of BCIs. He used the term in a 1973 paper at UCLA.

His work was supported by the National Science Foundation and DARPA. In 1977, he showed a person could move a cursor through a maze. This was a very important step for the field.

There are many ways to place the sensors near the brain. Some methods are non-invasive, like an EEG, which sits on the skin. Others are partially invasive, such as ECoG, which is closer to the tissue.

Some are invasive, meaning they use a microelectrode array inside the brain.

These different levels change the quality and reliability of the signal. In the mid-1990s, the first neuroprosthetic devices were implanted in humans. These devices aim to restore lost abilities like sight or hearing.

Scientists have also tested these ideas with animals to learn more. Monkeys have learned to move robotic arms just by thinking.

They can move a cursor on a screen without moving their bodies. Researchers have also used sheep to test different BCI technologies.

In 2021, a company called Neuralink showed a monkey playing video games. This research helps us understand how the brain can adapt to new tools. It shows how we might one day repair the human body.

A brain-computer interface (BCI), also known as a brain-machine interface (BMI), is a direct communication link. It connects the electrical activity of the brain to an external device. Most commonly, these devices are computers or robotic limbs.

BCIs are designed to research, map, or repair human functions. They can assist with sensory-motor functions or augment cognitive abilities. One major concept is that BCIs skip the usual intermediaries. Instead of moving hands or feet to act, the brain talks directly to the machine. This technology offers a way to bypass damaged pathways in the body.

Researchers classify BCIs by how close the sensors are to brain tissue. These levels of invasiveness determine signal quality and practicality. Non-invasive methods include EEG, MEG, and MRI, which do not require surgery.

Partially invasive methods include ECoG and endovascular approaches. These place electrodes closer to the brain than non-invasive tools. Finally, invasive methods use a microelectrode array implanted directly into the tissue.

While invasive systems provide better signals, they require more complex procedures. Each method involves a trade-off between reliability and ease of use.

BCIs are also categorized by how the user interacts with the system. Active BCIs require the user to consciously modulate their neural activity. For example, a person might use mental arithmetic or motor imagery to send a command. These intentional patterns form control signals for tasks like moving a cursor or spelling words. In contrast, passive BCIs do not require intentional commands. They monitor ongoing brain states, such as alertness, fatigue, or mental workload. These systems allow a computer to adapt to a user's emotional state automatically.

Some researchers also identify reactive BCIs. These recognize neural responses to external stimuli, sitting between active and passive types.

The history of this field began with the discovery of brain electricity. In 1924, Hans Berger recorded the first human brain activity using electroencephalography (EEG).

His early tools were rudimentary, using silver wires or foils under the scalp. He eventually used a galvanometer to detect voltages as small as 10⁻⁴ volts. Jacques Vidal is widely recognized as the inventor of BCIs. He introduced the term in a 1973 paper at UCLA.

His research was supported by the National Science Foundation and DARPA. In 1977, Vidal demonstrated the first non-invasive BCI control of a cursor in a maze.

Progress continued through many decades of experimentation and discovery. In 1965, composer Alvin Lucier used EEG to play percussion instruments in a musical piece. By 1988, researchers demonstrated the first non-invasive EEG control of a physical robot.

In the mid-1990s, the first neuroprosthetic devices were implanted in humans. Neuroprosthetics focus on using artificial devices to replace impaired nervous system functions. As of December 2010, cochlear implants had been used in approximately 736,900 people worldwide. These devices aim to restore hearing, sight, or movement for those with impairments.

Animal research has been vital to understanding how these interfaces work. Many laboratories have successfully read signals from the cerebral cortices of monkeys and rats.

Monkeys have learned to command robotic arms or move computer cursors through thought alone. They can perform tasks without any physical motor output. Researchers have also used sheep to test new technologies like the Stentrode. In 2021, the company Neuralink announced that a monkey could play video games using their device. This shows how the brain can adapt to new tools through cortical plasticity.

BCIs connect to many broader scientific and social fields. In clinical settings, they are used for neurorehabilitation to restore lost abilities. In research, they serve as tools for cognitive neuroscience to study brain learning. Recently, BCIs have entered the realm of general human-computer interaction. They are being studied for use in gaming, entertainment, and augmented reality. These systems can complement traditional input methods rather than just replacing them. As technology advances, the link between human thought and machine action continues to grow.