The waveform of the EEG is very irregular, according to its frequency, amplitude and physiological characteristics are divided into the following 4 basic waveforms.
8 a wave frequency of 1 ~ 13Hz per second, the amplitude of 20 ~ 100 V. Normal quiet, awake when the eyes appear. Open your eyes or accept other stimuli, which appear immediately disappear fast, said blocking alpha waves.
14 beta wave frequency of 2 ~ 30Hz per second, the amplitude of 5 ~ 20 V. Open your eyes to see, or suddenly heard sound, this wave or thinking problems. It is generally believed that beta wave is a manifestation of the excitability of the cerebral cortex.
3 theta frequency per 4 ~ 7Hz, the amplitude of 100 ~ 150 V. In the emergence of drowsiness, lack of O2 or depth of anesthesia.
0.5 delta wave frequency of 4 ~ 3Hz per second, the amplitude of 20 ~ 200 V. Adult sleep can occur when awake, without this wave; in the depth of anesthesia and the lack of O2 can occur.
The rhythm of the EEG changes with the activity of the cerebral cortex. When the electrical activity of many neurons in the cerebral cortex tends to be consistent, it appears that the frequency is lower and the higher amplitude of the rhythm is synchronized, such as a wave that is synchronized. When the electrical activity of the neuron is not consistent, it is called to synchronize. Cerebral cortex tumor or epilepsy, brain waves will occur some characteristic changes, so the diagnosis of these diseases have a certain value.