Alpha waves are rhythmical waves that occur at frequencies between 8 and 13 cycles per second and are found in the EEG of almost all normal adult people when they are awake and in a quiet, resting state of cerebration.These waves occur most intensely in the occipital region but can also be recorded from the parietal and frontal regions of the scalp.Their voltage usually is about fifty microvolts.During deep sleep, the alpha waves disappear.
Beta waves occur at frequencies greater than 14 cycles per second and as high as 80 cycles per second.They are recorded mainly from the parietal and frontal regions during specific activation of these part of the brain.
Theta waves have frequencies between 4 and 7 cycles per second.They occur normally in the parietal and temporal regions in children, but they also occur during emotional stress in some adults,particularly during disappointment and frustration.Theta waves also occur in many brain disorders, often in degenerative brain states.
Delta waves include all the waves of the EEG with frequencies less than 3.5 cycles per second, and they often have voltage two to four times greater than most other types of brain waves.They occur in very deep sleep, in infancy, and in serious organic brain disease.Therefore delta waves can occur strictly in the cortex independent of activities in lower regions of the brain.
Beta waves occur at frequencies greater than 14 cycles per second and as high as 80 cycles per second.They are recorded mainly from the parietal and frontal regions during specific activation of these part of the brain.
Theta waves have frequencies between 4 and 7 cycles per second.They occur normally in the parietal and temporal regions in children, but they also occur during emotional stress in some adults,particularly during disappointment and frustration.Theta waves also occur in many brain disorders, often in degenerative brain states.
Delta waves include all the waves of the EEG with frequencies less than 3.5 cycles per second, and they often have voltage two to four times greater than most other types of brain waves.They occur in very deep sleep, in infancy, and in serious organic brain disease.Therefore delta waves can occur strictly in the cortex independent of activities in lower regions of the brain.