EEG signals are normally classified according to their frequency and signal level. The following tables shows some of the EEG signals, their location and its associated body function.
EEG frequency range, location, and mind state
The EEG acquired signals, frequency range and the associated brain activities are elaborated below Gamma 27 Hz and above Gamma is associated with the formation of ideas, language and memory processing, and various types of learning. Gamma waves have been shown to disappear during deep sleep induced by anaesthesia, but return with the transition back to a wakeful state.
Beta 12 Hz - 27 Hz Generally the mental state most people are in during the day and most of their waking lives. Usually, this state in itself is uneventful, but don't underestimate its importance. Many people lack sufficient beta activity, which can cause mental or emotional disorders such as depression and insomnia. Stimulating beta activity can improve emotional stability, energy levels, attentiveness and concentration.
Alpha 8 Hz - 12 Hz Awake but relaxed and not processing much information. When you get up in the morning and just before sleep, you are naturally in this state. When you close your eyes your brain automatically starts producing more alpha waves. Many studies monitoring the EEG activity of experienced mediators have revealed strong increases in alpha activity. Alpha activity has also been connected to the ability to recall memories, lessened discomfort and pain, and reductions in stress and anxiety.
Theta 3 Hz - 8 Hz Light sleep or extreme relaxation.Theta is also a very receptive mental state that has proven useful for hypnotherapy, as well as self-hypnosis using recorded affirmations and suggestions.
Delta 0.2 Hz - 3 Hz Deep, dreamless sleep. Delta is the slowest band of brainwaves. When your dominant brainwave is delta, your body is healing itself and "resetting" its internal clocks. You do not dream in this state and are completely unconscious.
mu 8-12 Hz spontaneous EEG wave associated with motor activities and Maximally recorded over motor cortex ,They diminish with movement or the intention to move. Mu wave is in the same frequency band as in the alpha wave , but is recorded over occipital cortex.