Bioelectricity is one of the basic characteristics of life activities, and all kinds of living things have electrical activities, from whales to bacteria, with bioelectricity of different strengths. In fact, the word "cell" in English also means battery. Countless cells are equivalent to miniature small batteries and are the source of bioelectricity.
Bioelectricity also exists widely in human body, because all tissues and organs of human body are composed of cells. For the brain, brain cells are "miniature power stations" in the brain.
Our brains have been generating brain waves. As early as 1857, R.Caton, a young British physiologist, recorded EEG activity in rabbit and monkey brains, and published a paper entitled "Study on gray matter electrical phenomena in the brain", but it did not attract attention at that time. 15 years later, A.Beck published a paper on brain waves again, which set off a craze for studying brain waves. It was not until 1924 that the German psychiatrist H.Berger really recorded the brain waves of the human brain, and the human EEG was born.
These are spontaneous rhythmic neuroelectrical activities, the frequency of which varies between 1-30 times per second, and can be divided into four bands, namely δ (1-3Hz), θ (4-7Hz), α (8- 13Hz) and β (/kloc-0).
Δ wave, the frequency is 1-3 times per second, which can appear when people are in infancy or immature intelligence, and when adults are in extreme fatigue and lethargy.
Theta wave, with a frequency of 4-7 times per second, is extremely significant when adults are depressed and mentally ill. But this wave is the main component of EEG in adolescents (10- 17 years old).
The frequency of alpha wave is 8- 13 times per second, with an average of about 10 times. It is the basic rhythm of normal people's brain waves, and its frequency is quite constant without external stimulation. This rhythm is most obvious when people are awake, quiet and close their eyes. When they open their eyes or receive other stimuli, the alpha wave will disappear immediately.
Beta wave, the frequency is 14-30 times per second. This kind of wave appears when people are nervous, excited or excited. When people wake up from sleep, the original slow-wave rhythm can be immediately replaced by this rhythm.
When people are in a happy mood or meditating, the stimulated β wave, δ wave or θ wave is weakened at this time, while the α wave is relatively strengthened. Because this waveform is closest to the bioelectric rhythm of the right brain, people's inspiration state appears.
The rhythm of brain waves comes from the thalamus. Scientists once cut off the connection between animal cerebral cortex and thalamus, and the rhythm of brain waves disappeared, while the electrical rhythm activity of thalamus still existed. If the thalamus is stimulated with an electric pulse of 8- 13Hz, brain waves similar to alpha rhythm can appear in the cerebral cortex. Therefore, the maintenance of normal brain waves requires that the brain and thalamus are intact.
In addition, everyone knows that "electricity generates magnetism, and magnetism generates electricity", which means that electric field and magnetic field are always accompanied. Since the human brain has changes in bioelectricity or electric field, there must be a magnetic field. Sure enough, the scientist Cohen first measured the brain magnetic field in 1968. Due to the weak magnetic field of human brain and the interference of the earth's magnetic field and other magnetic fields, it is necessary to have a good magnetic shielding room and a highly sensitive measuring instrument for measurement. 197 1 year, someone abroad recorded the magnetoencephalogram for the first time in the magnetic shielding room. Magnetoencephalography (MEG) is a non-invasive detection method, which can determine the exciting parts in the brain under different physiological activities or psychological States, and is undoubtedly one of the effective methods to detect brain diseases.
Brain wave or EEG is a sensitive objective index, which can not only be used in the basic theoretical research of brain science, but also has more important significance in its clinical practice and is closely related to human life and health.
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