Our nervous system operates through electrical impulses. Faint electric currents circulate through our nerves when they transmit impulses to the brain or the brain to effector organs.
The complexity of the brain and the structure of own ignorance prevents us to predict exactly which frequencies or signals can associate each type of activity. We can not, as in a digital circuit, separate impulses individually analyzing each type of transmitted signal. The complexity of the signals in the case is huge.
However, the research reveals the existence of some well-defined rhythms, like "clock signals" and responsible for the onset of electrical current intensities and frequencies in certain ranges and can be associated with important biological phenomena.
A deeper knowledge of such currents and rhythms can lead to its use in control and interfacing devices. Already known projects in which the rhythms or the signals generated in certain specific activities are used to control devices such as a cursor on a computer screen thus enabling the selection of automatic operations for a quadriplegic.
Below we give a description of these rhythms with their main characteristics.
ALPHA
This rhythm produces 10 to 100 uV intensity pulses in a frequency band going from 7 to 13 Hz. We may associate the alpha rhythm to quiet state, relaxation, weightlessness, etc.
THETA
This rhythm generates signals whose intensities are between 50 to 200 uV at a frequency range from 3 to 7 Hz. We can associate this rhythm doubt, solving difficult problems, concern for the future, daydreaming, etc.
DELTA
For this rhythm with intensities 10-50 uV a range of frequency is very low, between 0.2 and 3 Hz. This rhythm is associated with the state of deep sleep, hypnotic trance, etc.
BETA
The beta rhythm has signals whose strengths are in the range 10-50 uV and frequencies between 13 and 28Hz. We can associate this rhythm the state of worry, fear, attention, stress, surprise, etc.
They were also detected signals from 0.01 to 0.1 uV a range of very high frequencies between 50 MHz and 1 GHz and are little known.
These signals, by their frequency band can give rise to electromagnetic waves of greater penetration and, thus, can be detected at a distance of people's heads.
The detection of low frequency signals is usually done by means of electrodes that are attached to the patient's head. The generated signals are then passed by the liquid medium there between the brain itself and the electrodes, generating currents that are detected by the apparatus.
The eletroencefalógrafos are examples of devices that can be used in the recording of low frequency signals generated by brain activity.
SEARCH
Searches that use digital processing of these signals (using microprocessors or DSPs) can lead to very interesting practical applications involving directly mechatronics.
One of them, as already we said, would be to use rhythms or frequencies that can be generated in a conscious way to control automations such as the movement of wheelchairs or even mechanical arms.
Another possibility is to have practical applications, is the cursor control on a computer screen thereby enabling quadriplegics to use it without the need for any movement.
Maybe in the future (not very far) we have equipment that can identify specific signals that are generated when we express certain intentions and respond to them with effective actions. Suffice then think we want the light of our living light, so that the operator do from own signals generated by the brain.
Remember this is not science fiction, because 40 years ago no one believed that would be possible to have in the watch a world-wide intercom and that gives their position at any point on the globe (GPS). The stories of Dick Tracy were considered pure fiction making use of things that we have today in our power ...
