
Brain Training The Why? & How?
Various forms of mental illness and issues are associated with abnormal patterns of resting electroencephalogram (EEG) activity (Zietsch et al 2007). EEG measures the electrical activity of the brain produced by the circuitry and function of the underlying pyramidal cells (Schaul, 1998). Quantification of EEG activity is achieved by dividing the frequency spectrum into discrete ranges (bands), and with a transformation of the data, determining the amplitude or ‘power’ of each range. EEG band power varies greatly between individuals (Vogel, 2000), is stable within an individual in a given condition (Williams et al., 2005), and changes according to mental state (Moretti et al., 2004), task demands (Klimesch, 1999), and age (Li et al., 1996; McEvoy et al., 2001). The frequency spectrum of the bands can be divided into fixed bands: delta (up to 3 Hz), theta (3–8 Hz), alpha (8–13 Hz), beta (13–25 Hz)) or other individually aligned bands (Klimesch, 1999). These fixed bands, measured by EEG, are related to a continuum of states ranging from stress state, alertness to resting state, hypnosis, and sleep.
BRAIN WAVE | Frequency Range (Hz) | Associated Mental State |
Gamma Waves | 25.0 – 60.0 | Scientist still researching. Time and Space seem to be likely. |
Beta | 15.0 – 25.0 | Awake, normal alert consciousness |
Sensory Motor Response (SMR) Low Beta |
12.0 – 15.0 | Voluntary body functioning |
Alpha | 7.5 – 12.0 | Relaxation, calm, lucid, not thinking |
Theta | 3.0 – 7.5 | Deep relaxation, emotions, memories |
Delta | 0 – 3.0 | Deep dreamless sleep, sustains the functioning of the physical body |
Table 1. Classification of common frequencies of brain waves measured by EEG and associated mental states.
