EEG will combine with TMS in future BCIs

Published in

Embla Tech

6 min readApr 8, 2018

Electroencephalography (EEG) is one of the well-known medical procedure using for capturing human brain behavior. Basically, EEG scan is recording electrical activity of the human brain so doctors can use these data to diagnose diseases. In the past EEG was used by doctors and researchers but now it is becoming a basic computer activity for everyday use. There are lot of EEG headsets out in the market. Some are very cheap while others are expensive. These EEG headsets are mentioned in different terms such as “Mind Controller”, “Brainwave Controller”, “Brain Computer Interface”, etc. Main functionality of an EEG headset is to capture brain waves. Some people may refer to Brain Computer Interface is only powered by EEG technology. This is not completely correct. There can be lot of variations. In this article I will also look at Transcranial Magnetic Stimulation (TMS) powered Brain Computer Interfaces (BCI) and their usage.

Emotiv Epoc+ hi-resolution 14 channel mobile EEG headset

Neurosky mindwave single channel mobile EEG headset

EEG Brain Computer Interfaces

Most EEG headsets contain one or more EEG recorders and Signal encoder. EEG recorder is a simple electrode that should be placed on top of a specific point on the human head. When you wear these devices, electrodes will be self-placed at correct locations according to the headset design. These electrodes have some basic sensors to detect voltage variations around it simply by using electric induction principals. Inbuilt microprocessor will encode these voltage variations as digital signals and transmit them to the host. The host can be a computer, a mobile phone or any other processing device. This system is functioning as a simple Brain Computer Interface.

Applications of modern commercial EEG headsets

Usage can be divided into several fields, especially medical science and computer science. This technology is becoming a main bridge between medical science and computer knowledge. Doctors and engineers are getting together and develop different devices to make human life better. Together they have built robotic solutions for disable people. Using thoughts to control a robot arm is a good example. For a person who lost an arm can function using a robotic arm controlled by that person’s thoughts. Mind-controlled wheel chair is another example. It is basically used by paralyzed people. Prof Stephen Hawking was one of the well-known scientist who used this type of chair. Engineers and computer scientists have developed some entertainment stuff like mind-controlled drones, meditation visualizers, mind-controlled toys and a lot more devices.

Technical backend of a mobile EEG devices

Basic functionality of a mobile EEG device is to capture brain waves, encode them as digital signals and send them to the host. The host has code (the driver software and the utility software) running in the background, so the signals received from the headset will be processed in order to output useful information. Some predefined wave patterns are used to compare with the inputs. The computer (or the host device) can interpret brain state and the brainwave activities. For each and every complex activity, the brain emits complex brainwaves, a combination of primitive waves.

Brainwave types and Brain Activities

For now, scientists have defined 6 brainwave categories based on their frequency. (Refer the below table) Inside the brain these waves are actually electric impulses which are transmitted through neurons. Scientists have already studied the relationship between mental states, brain commands, and brainwaves. For each brain command there is a specific brainwave pattern. Brain command can sometimes be called as a behavior. “Move my left hand and scratch my head” is a brain command. These are dynamic actions controlled by our brain.

Imagine what if we can record brainwave patterns for a specific action (or a command). Once we record a brainwave pattern, computers can use this pattern to trigger an electric device, for example a robot-arm. This is the core concept behind the mind-controlled devices. Computer software can be trained for a specific task which can be triggered by our thoughts. Once it triggers a predefined, trained task, software will activate relevant sections of the electric hardware device. One example is servo motors.

Infra-low (<0.5Hz)
Delta waves (0.5–3Hz)
Theta waves (3–8Hz)
Alpha waves (8–12Hz)
Beta waves (12–38Hz)
Gamma waves (38–42Hz)

Brainwaves also defines current static states, like mental state — how you feel right now. For each emotion there is a specific brainwave pattern. This can be a basic signal or a combination of several categories shown above. Some meditation practitioners are wearing EEG headsets to monitor their own meditation progress. Muse is a dedicated headset designed for meditation.

EEG to control own body elements

BCIs are mainly used to control external electric devices but still they can be used to control your own body parts to re-grant missing control. For example, if someone faced an accident and partially damaged the nerve system at the middle of the arm, this person won’t be able to control the fingers. Because the Central nerve system can’t transmit signals to the finger control muscles. In this case scientists have discovered a way to re-grant control using a BCI device and implanted electrodes. These electrodes should be planted at the exact locations where they meet control nerves in the hand. While EEG headset captures finger movement command pattern, these electric signals must be redirected to the implanted electrodes via a special amplification and routing device, so the exact brain command will bypass the damaged area of the nerve system and reach the control nerve of the destination. With aid of these kind of BCI devices, patients can re-grant control over body parts that is not directly damaged but are rendered useless by other body damages. Some advanced BCI’s require brain gate (a small electrode chip) to be planted inside the brain which also requires a small surgery.

TMS to connect two discrete brains together

TMS which is called “Transcranial Magnetic Stimulation” is the most advanced type of BCI. It has inverse functionality of typical EEG Interface. Basically, EEG Interface transmit signals to the computer while TMS Interface transmit signals to the brain, which will open the gate to communicate between two brains directly. TMS headset is not simple like EEG because it has a lot of electrodes (channels) and magnetic field generators. High resolution TMS devices may have at least 48 channels. This BCIs looks like a hat and covers the entire head. Basic functionality is exactly the inverse of EEG. Each electrode has a magnetic field generator, each electrode can generate different magnetic fields, which may induce currents around the electrodes. Since the electrodes are placed on the head and close to the brain, particular areas will get artificial stimulation based on the TMS device inputs.

When TMS technology is mixed with EEG, we have a brain gate. One brain can directly communicate with another intelligence. Let me quickly add that this is still in an experimental stage. Scientists have practically proven this concept onto a certain level. Still we have doubts about the positive benefits of BTB communication, and I can sense there are some dangerous aspects to it. In the future, there will be bio locks. Instead of locking a one person in jail, TMS device will take control over that person. This is a common scenario found on several sci-fi movies. Instead of mind-controlled robots, there will be mind-locked humans as slaves. There are lot more harmful issues of the TMS technology.

Using a EEG headset, BCI and a couple of electrodes, one person can also control body parts of another person. This is practically proven by some scientists. First EEG device will capture brain commands from the first person. The command is transmitted to the computer software. Imagine this command is to bend the fingers. Instead of direct brain TMS, the computer bypass signals directly to the control nerve of the hand of second person. Second person should have implanted electrodes. When the first person thinks about moving fingers, signal will stimulate second persons hand control nerves, which may result action execution. Fingers will get bend without control. This procedure is sometimes called “Functional Electrical Stimulation”.

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