Neurons Create Brainwaves

The human brain is made up of billions of interconnected neurons about the size of a pinhead. As neurons interact, patterns manifest as singular thoughts such as a math calculation, and broad emotional states such as attention. The average human thinks 70,000 thoughts each day. As a by-product, every interaction between neurons creates a miniscule electrical discharge, measurable by EEG (electroencephalogram) machines. By themselves, these charges are impossible to measure from outside the skull. However, a dominant mental state, driven by collective neuron activity created by hundreds of thousands concurrent discharges, can be measured.

Through a century of experimentation, neuroscience experts have determined where specific activity occurs within the brain. Motor control of limbs occurs in the top of the brain, for example. Vision is processed in the back of the brain. From an evolutionary point of view, these basic functions are present in most animals. As humans evolved into more intelligent creatures, the pre-frontal cortex in the front of the brain is where higher thinking occurs. Emotions, mental states, concentration, etc. are all dominant in this area. This is the primary reason for NeuroSky’s main sensor placement on a position known as FP1.

Different brain states are the result of different patterns of neural interaction. These patterns lead to waves characterized by different amplitudes and frequencies. As examples, brainwaves between 12 and 30 hertz, Beta Waves, are associated with concentration, while waves between 8 and 12 hertz, Alpha Waves, are associated with calm relaxation. Often overshadowing brainwaves, the contraction of muscles is also associated with unique wave patterns, called EMG. Isolating these EMG patterns is how some NeuroSky devices detect eye blinks.


The single sensor on FP1 provides a high degree of freedom; NeuroSky devices can measure multiple mental states simultaneously. The physics of brainwaves is virtually identical to the physics of sound waves where a single microphone can pick up the complexity of a concert.

All electrical devices, including computers, lightbulbs, wall sockets, etc., leak some level of ambient “noise”. This noise is often loud enough to obfuscate brainwaves. As a result, laboratory EEG devices will pick up random readings when both the reference electrode and the primary electrode are connected to an object that is not emitting brainwaves. Sensing mental activity through electrical noise is like trying to eavesdrop on a conversation at a loud ballgame - from outside the stadium. In the past, traditional EEG devices have circumvented this problem by measuring brainwaves in strictly controlled environments where no lights, devices, etc. interfere with the EEG signal. To increase the EEG brainwave signal, a thick medical gel is used for conductivity. As EEG devices migrate from the laboratory to homes, most people do not have rooms devoid of electronic interference, nor do they want to apply a conductive liquid to their head every time they use an EEG device. NeuroSky’s approaches to gel-free sensors and noisy environments mitigate these challenges.

Part of NeuroSky’s IP involves noise cancellation. Signal amplification makes the raw brainwave signal stronger. Filtering protocols eliminate known noise frequencies such as muscle, pulse and electrical devices. Notch filters eliminate electrical noise from the grid, which varies from 50Hz to 60Hz, depending on worldwide geography. Filter technology remains at the forefront of NeuroSky R&D, and future products will refine this imperfect capability.

Additional IP involves electrical engineering. Extrapolating EEG brainwave signals from noise requires both a reference point and an electrical circuit grounding. The grounding makes the body voltage the same as the headset. The reference is used to subtract the common ambient noise through a process known as common mode rejection. The earlobe is a location that experiences the same ambient noise as the NeuroSky forehead sensor but with minimal neural activity. Hence, it is crucial that the ear connection be securely fit.


Electrical signals in neurons are not transmitted the same way electrical signals that travel along wires are nor do they have a source of electricity being fed into them. Instead each neuron creates its own electrical charge. Every time one of these electrical signals reach the end of a neuron, chemicals are released that tell the surrounding neurons to create their own electrical signals. These signals are called “action potentials” and when a neuron creates one it is said to have “fired”.

It is possible for atoms and molecules to have a positive or negative charge, these charged particles are known as ions; positive and negative ions want to be paired together like the positive and negative poles of two magnets. When no signal is being transmitted a neuron uses pumps to move positive ions outside of the cell. These pumps require a great deal of energy because the positive ions want to go back into the now negatively charged cell. The energy required to power these pumps comes from ATP, the same molecule that carries energy to muscles throughout the body.

The first law of thermodynamics states that energy can only change forms but cannot be created or destroyed. The energy used to power the pumps becomes stored as the charge differential between the inside and outside of the cell. When that differential is removed by the flow of positive ions into the cell, the stored energy is released in the form of small waves. Like little waves combining to create big waves in the ocean, as thousands of neurons fire, the little waves come together to create the larger waves knows as brain waves. It is these dominant brainwaves that are measured by NeuroSky devices.

Brain computer interface (BCI) is a system that translates the electrophysiological activity or metabolic rate of an organic organisms’ nervous system into signals that can be interpreted by a mechanical device. The idea of BCI has captured the public imagination for a century; Baby Boomers grew up with the Six Million Dollar Man, a television series featuring a man outfitted with neural prosthesis after an injury. As early as 1908, Le Nyctalope, arguably the first super hero, was also the first BCI described in literature (sporting an artificial heart.) BCI is no longer relegated to fiction, in fact research into the subject has flourished throughout the last decade in which humans, nonhuman primates, and rodents have directly communicated with electrical devices through neural activity (Ganguly and Carmen, 2009; Stieglitz 2009).

Despite the explosion of research into BCI, just a few years ago one would be hard pressed to find a device recording central nervous system activity and using it to control an electronic device below tens of thousands of dollars.


NeuroSky is the world leader in bringing BCI capabilities out of the laboratory and to the general public. Because of NeuroSky’s advances, anyone can now influence the functions of an electronic device by thought alone, in the privacy of their own home. Research institutions can collect previously unprecedented levels of field data on brain functions. And businesses can add BCI capabilities to their products.

NeuroSky devices are affordable, portable, and wireless. Most EEG based consumer devises on the market are essentially stripped down versions of medical EEGs. The core technology behind NeuroSky devices has been built from the ground up. This has allowed NeuroSky to inexpensively produce a chip that that filters out the ambient waves present in most uncontrolled conditions and effectively measures neural activity in virtually any condition with 96% the accuracy of similarly configured research grade EEGs.

A number of companies claim to have been the first to release a consumer based EEG. The first was actually produced by Interactive Product line. Though NeuroSky developed the first BCI device available to the general public under a thousand dollars, NeuroSky’s primary product is chips. These have been the basis for every commercially successful consumer BCI product every created. NeuroSky allows for companies with no experience in EEG based technology to effectively incorporate it into their products.

NeuroSky does not control thoughts

All NeuroSky technology is unidirectional; where information travels from the brain to the device but not the other way around. It would be physically impossible to use a NeuroSky product to control someone’s thoughts. That said, using a NeuroSky device on a regular basis might make it easier to reach certain mental states but only in the way doing math problems can make one better at math.

Safety is Paramount

NeuroSky devices only receive data the brain is always emitting. Moreover, the wireless signals are purposely kept to a minimum because they would interfere with the brainwave recording itself. Thus the strength of wireless signals produced by NeuroSky devices make those produced by cell phones look like a jet engine.

Other BioSensors

Galvanic skin response is a technology that has been available to the general public for decades; best known for its use in the classic “lie detector”. Often confused with EEG, galvanic skin response can be used to approximate a narrow range of mental states through measuring the electrical resistance of skin. Skin conductivity changes based on hormones the brain produces when in a state of emotional arousal. Galvanic skin response cannot distinguish between different forms of arousal ie. anger, fear, startle response, and sexual arousal.

It is important to note that galvanic skin response does not directly measure states of mind directly, but rather their effects on the body. Neurosky devices measure local field potentials, aka brain waves, which are directly caused by neural activity - No NeuroSky device has ever used galvanic skin response.

In the future, galvanic skin response (GSR), muscle electromyography (EMG), heartbeat electrocardiography (ECG or EKG), retinal electrooculography (EOG), blood oximetry and other biosensor areas will be logical areas of innovation for NeuroSky. For information concerning our next generation sensor, which will measure EMG, EOG and EKG, please speak with a NeuroSky sales rep.