Some science behind the scenes

EEG - Electroencephalograph

An electroencephalograph (EEG) measures the electrical activation of the brain from scalp sites located over the human cortex. The EEG shows the amplitude of electrical activity at each cortical site, the amplitude and relative power of various wave forms at each site, and the degree to which each cortical site fires in conjunction with other cortical sites (coherence and symmetry). It  uses precious metal electrodes to detect a voltage between at least two electrodes located on the scalp.

It is not helpful to go into the very detailed workings of the instrument, all we need to know is that it measures brain waves and can measure the  main frequency ranges including delta, theta, alpha, the sensorimotor rhythm, low beta, high beta, and gamma. It is worth mentioning that the specific points defining the frequency ranges are not universally accepted, but if we take an approximate banding the ranges are as follows.

The synchronous delta rhythm ranges from 0.5 to 3.5 Hz. Delta is the dominant frequency from ages 1 to 2.

The synchronous theta rhythm ranges from 4 to 7 Hz. Theta is the dominant frequency in healthy young children and is associated with drowsiness or starting to sleep, REM sleep, hypnagogic imagery (intense imagery experienced before the onset of sleep) and hypnosis.

The synchronous alpha rhythm ranges from 8 to 13 Hz and is defined by its waveform and not by its frequency. Alpha activity can be observed in about 75% of awake, relaxed individuals and is replaced by low-amplitude desynchronized beta activity during movement, complex problem-solving, and visual focusing.
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The synchronous sensorimotor rhythm (SMR) ranges from 12 to 15 Hz and is located over the sensorimotor cortex (central sulcus). The sensorimotor rhythm is associated with the inhibition of movement and reduced muscle tone.

The beta rhythm consists of asynchronous waves and can be divided into low beta and high beta ranges (13–21 Hz and 20–32 Hz). Low beta is associated with activation and focused thinking. High beta is associated with anxiety, hypervigilance, panic, peak performance, and worry.

EEG activity from 36 to 44 Hz is also referred to as gamma. Gamma activity is associated with “perception of meaning and meditative awareness”.

Overall the feedback from an EEG may be a very useful training aid.  Though intrusive, this factor does not matter too much in the early training stages, when the principle objective is trying to learn if you have got it right.

The main disadvantage with EEGs are they are expensive and used principally for medical reasons, so you would undoubtedly have difficulty finding one and using one.

Observations

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