Brain waves are the physical representation of the brain’s electrical charge and activity. Electroencephalography (EEG) is the technique used to record electrical activity. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. Brain wave activity is recorded from different standard sites on the scalp according to the international electrode placement system. Recording electrical activity requires measurement of voltage between two electrode sites. The electrical activity between electrode pairs is evaluated in terms of amplitude and frequency. Amplitude ranges from 5 to 200 μV. Frequency of EEG activity generally ranges from 0 to 100 Hz (American EEG Society 1994; Niedermeyer and da Silva 2004; Towle et al. 1993).
Brain wave activity can be recorded during wakefulness as well as sleep. With regards to sleep, stage N1 sleep or drowsiness is characterized by a fading of the alpha waves and...
References and Further Reading
- Niedermeyer, E., & da Silva, F. L. (2004). Electroencephalography: Basic principles, clinical applications, and related fields. Philadelphia: Lippincot Williams & Wilkins.Google Scholar