Delta wave – (0.1 – 3 Hz)
A delta wave is a high amplitude brain wave with a frequency of oscillation between 0–4 hertz. Delta waves, like other brain waves, are recorded with an electroencephalogram (EEG) and are usually associated with the deep stage 3 of NREM sleep, also known as slow-wave sleep (SWS), and aid in characterizing the depth of sleep. Wikipedia, Delta Wave
Theta wave – (4 – 7 Hz)
The theta rhythm is an oscillatory pattern in electroencephalography (EEG) signals recorded either from inside the brain or from electrodes glued to the scalp. Two types of theta rhythm have been described. The "hippocampal theta rhythm" is a strong oscillation that can be observed in the hippocampus and other brain structures in numerous species of mammals including rodents, rabbits, dogs, cats, bats, and marsupials. "Cortical theta rhythms" are low-frequency components of scalp EEG, usually recorded from humans. Theta rhythms can be quantified using Quantitative electroencephalography (qEEG) using freely available toolboxes, such as, EEGLAB or the Neurophysiological Biomarker Toolbox (NBT). Wikipedia, Theta Wave
Alpha wave – (8 – 15 Hz)
Alpha waves are neural oscillations in the frequency range of 7.5–12.5 Hz arising from synchronous and coherent (in phase or constructive) electrical activity of thalamic pacemaker cells in humans. They are also called Berger's wave in memory of the founder of EEG.
Alpha waves are one type of brain waves detected either by electroencephalography (EEG) or magnetoencephalography (MEG) and predominantly originate from the occipital lobe during wakeful relaxation with closed eyes. Alpha waves are reduced with open eyes, drowsiness and sleep. Historically, they were thought to represent the activity of the visual cortex in an idle state. More recent papers have argued that they inhibit areas of the cortex not in use, or alternatively that they play an active role in network coordination and communication.2 Occipital alpha waves during periods of eyes closed are the strongest EEG brain signals.
Alpha waves can be quantified using Quantitative electroencephalography (qEEG) using freely available toolboxes, such as, EEGLAB or the Neurophysiological Biomarker Toolbox. Wikipedia, Alpha Wave
Mu wave – (7.5 – 12.5 Hz)
An alpha-like variant called mu (μ) can be found over the motor cortex (central scalp) that is reduced with movement, or the intention to move. Alpha waves do not start to appear until three years of age. Wikipedia, Mu Wave
SMR wave – (12.5 – 15.5 Hz)
The sensorimotor rhythm (SMR) is brain wave rhythm. It is an oscillatory idle rhythm of synchronized electromagnetic brain activity. It appears in spindles in recordings of EEG, MEG, and ECoG over the sensorimotor cortex. For most individuals, the frequency of the SMR is in the range of 13 to 15 Hz. Wikipedia, SMR Wave
Beta wave – (16 – 31 Hz)
Beta wave, or beta rhythm, is the term used to designate the frequency range of human brain activity between 12.5 and 30 Hz (12.5 to 30 transitions or cycles per second). Beta waves are split into three sections: Low Beta Waves (12.5–16 Hz, "Beta 1 power"); Beta Waves (16.5–20 Hz, "Beta 2 power"); and High Beta Waves (20.5–28 Hz, "Beta 3 power"). Beta states are the states associated with normal waking consciousness. Beta waves can be quantified using Quantitative electroencephalography (qEEG) using freely available toolboxes, such as, EEGLAB or the Neurophysiological Biomarker Toolbox. Wikipedia, Beta Wave
Gamma Waves - (32 – 100 Hz)
A gamma wave is a pattern of neural oscillation in humans with a frequency between 25 and 100 Hz, though 40 Hz is typical.
According to a popular theory, gamma waves may be implicated in creating the unity of conscious perception (the binding problem). However, there is no agreement on the theory; as a researcher suggests: