What is a brain-computer interface?
Who are the intended users of a BCI?
Can a BCI be used to read people’s thoughts?
Can I buy a BCI?
Which technologies are used for BCIs?
What can be done with a BCI today?
Why is more BCI research needed?

What is a brain-computer interface?
A brain-computer interface (BCI) is a technology that uses observed brain signals to control a computer or device. The brain signals can be observed with multiple technologies, such as fMRI, EEG (electroencephalography, electrodes on the head), ECoG (electroencephalography, electrodes in the head), or MEG (magnetoencephalography, measurement of the magnetic field produced by the brain).
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Who are the intended users of a BCI?
BCIs are currently focused on people who are suffering from some form of paralysis (inability to control one’s muscles) due to disease, an accident, or birth abnormality. With the help of a BCI brain signals can bypass the muscles and directly control a computer mouse or other device. It is also conceivable that a BCI could be used to control a robot arm in the near future. In addition research is currently being done to develop BCIs for rehabilitation purposes and to help speedup other recovery therapies. A third application domain is BCI’s designed to add functionality to healthy people in contexts such as gaming or military operation.
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Can a BCI be used to read people’s thoughts?
No, it is not possible to read a person’s with a BCI. BCI’s are also not being developed with the goal of reading inner thoughts. Users of a BCI must fully concentrate and engage in a specific task that increases the activity of specific brain areas. The increase in brain activity can be detected and used to control a computer program. Hence, a BCI cannot decode what you are thinking but simply that you are thinking.
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Can I buy a BCI?
To date there is just one BCI focused on people suffering from paralysis that is commercially available. This BCI (http://www.intendix.com) uses EEG technology.

However, more and more devices based on EEG technology that can be coupled to a computer are appearing in stores. These BCI’s are generally intended for game play and are not suitable for use as an assistive communications device.

Implantable BCI’s are being developed. Prototypes have already been used, and an implantable BCI that works at home without the assistance of technicians is scheduled to be tested in 2014.
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Which technologies are used for BCIs?
At this time several different technologies are used to detect brain activity. Each of these technologies has its own pros and cons.

EEG uses electrodes placed on the head with adhesive or a special hat or headband. The electrodes can pick up the electrical signals produced by brain activity. Because the electrodes are some distance from the brain and the brain activity must travel though the scalp, the signal is faint and noisy. In addition hourly adjustments are often needed and require a highly trained technician.

Another technology involves small needle electrodes that are inserted into to brain tissue. Such implants are able to measure the activity of multiple individual brain cells (neurons). By using the precise activity of  a small group of neurons it is possible to control the movement of a robot arm. This technology has been used by a handful of subjects in the US for short periods, but is not yet ready for more general use. It remains unclear whether this technology can be made suitable for long term use or affordable for use outside of highly funded research groups.

It is also possible to place electrodes directly on the surface of the brain without penetrating or damaging the brain tissue. This technology is referred to as electroencephalography (ECoG). Because the brain signal does not have to travel though the skull to the electrodes the received brain signal is many times stronger than that measured with electrodes on the head (EEG). In addition due to the close proximity of the electrodes to the origin of the brain activity, the precise area of the brain that is active can also be much more accurately determined. An advantage that ECoG electrodes have over the needle electrodes is that they do not penetrate the brain tissue and thus the chance of an adverse reaction and/or the forming of scare tissue that renders the electrodes insensitive to brain activity is mush smaller. It is expected that ECoG electrodes will provide usable high quality BCI signal for many years. The Utrecht Neuro-Prosthesis uses ECoG electrodes placed on the surface of the brain.

Other technologies used to measure brain activity are only available in the lab or special centers. For example functional MRI can be used to record what area of the brain is active when a person performs a mental task in an MRI scanner. This signal can then be used for BCI. However, it is unlikely that MRI scanners will ever become small and simple enough for at home use. Functional MRI is a powerful tool for determining the best places on the brain to place other types of BCI sensors (such as ECoG) in an individual before surgery.

MEG (Magnetoencephalography) is another technology that can measure brain activity but requires a large machine that is not suitable for home use. However, MEG is another powerful tool in researching how the brain works, which is important for making BCI’s better and available to more people who can benefit from them .
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What can be done with a BCI today?
Today it is possible to control simple aspects of a computer, such as mouse position, or a device, such as opening or closing a robot hand. Films of BCI control of computer games and robotic devices with and without surgically implanted technology can be found on the internet. In addition more and more small companies are producing BCI or BCI-like game devices. For multiple reasons these gaming systems are not suitable for medical BCI applications, such as assistive communication devices.

Several labs in the US have recently shown that BCI control of a robot-arm is possible using needle electrodes implanted into the brain tissue. However, successful control has so far been limited to short sessions and has required the close assistance of technicians to keep the system working. Due to the risk of injury presented by a unintended robot are movement  the reliability of such a system has to be guaranteed for unassisted use. There is ongoing development of a robot arm that is coupled to sensors and cameras that allow it to detect and avoid movements that may cause injury. However, it is not clear whether the brain signal amplifiers and robotic equipment needed for such a device can be made suitable for at home use and if so how long it will be until such a device is commercially available.

A simpler BCI implant for people suffering from LIS is also being developed. Many BCI’s capable of producing a simple on/off signal that could be used to control button operated assistive technology devices (such as text generators) have been demonstrated. However, a major challenge for even such simple BCI systems is the reliability. Frequent mistakes (even if not dangerous) can quickly lead to frustration and disinterest of the user (and thus system failure). For this reason  it is important to develop a BCI system of sufficient quality to actually be used on a daily basis even if the system is very simple and limited in its capabilities. For example, a system that allowed a person suffering from LIS to slowly type a message without a assistance of a care giver, would already be a breakthrough in the field in that it would break the current barrier between what is theoretically possible with BCI systems and what an person in need of such a device can actually do with it.
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Why is more BCI research needed?
The technical capabilities of BCI systems are advancing a rapid rate as more and more interest in the field is generated. Improvements in the understanding of how the brain works, advances in the technology used to measure brain signal, more powerful and portable amplifiers, improved algorithms used to interpret the brain signal, faster and more powerful computers, and advancements in assistive devices have all contributed to advancing the field. However, the creation of usable BCI systems that help people suffering from function loss on a day-to-day basis requires continued improvements in each of these fields and their integration.

In addition, questions such as what it is like to use a BCI system on a daily basis and whether a BCI can improve the quality of life of an user (for example someone suffering from LIS) are just now starting to be explored. Even the most simple BCI system is extremely complex and the effects of many aspects of a BCI system important to usability and user satisfaction can only be tested when BCI systems are being used on a more routine basis. In addition, the effect of continuous use of a BCI system on the brain activity and functioning itself remain an important area to be explored. For these reasons BCI research will need to continue even after the technical challenges have been sufficiently met.
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