<p>The definition of quantitative EEG is very broad and encompasses all quantified EEG in term of phase, coherence, power and/or other brain-computer interfaces. However, for the sake of simplicity, we will refer to the quantitative EEG as a test comparing the electroencephalography of the individual (EEG) to a normative database, which is a database of “normal” people within the clients age range who are physiologically and psychologically healthy. The individual is assessed from the perspective of how many standard deviations from the norm their EEG data occurs within.&nbsp; This creates what we know as a “brain map.” Maps are taken using standard deviations from the norm by way of or power output (measured in microvolts squared or microvolts—amplitude and magnitude, respectively).&nbsp; &nbsp; &nbsp;</p><p>When recording, traditionally in the field of neurotherapy, the international 10-20 system for electrode placement is used (a 19-channel cap) and electrode impedance of less than five kilo ohms is used. Activity at the functional regions of the brain, including Brodmann areas, can be incorporated into the findings with the use of Low Resolution Brain Electromagnetic Tomography (LORETA) software.</p><p>Typically, an EEG is recorded in two conditions: eyes open and eyes closed. A clinician can use as many or as few databases as they wish, each database has its own high points and short comings.&nbsp; Depending on the database, data can be understood from a variety of different montages.&nbsp;</p><p>The images created by quantitative EEGs will show an overall view of the client’s brain waves (EEG) relative to a normative database of other people their own age. Colors are often used to indicate how many standard deviations they are from the normal population. Also (often) shown are connectivity issues in coherence (the stability of the phase relationship between different sites in the brain) and phase lag (a measure of how waveforms come into and out of synchronization).&nbsp;</p><p>Quantitative databases usually give an overall view of the individual’s data from a Fast Fourier Transform (FFT) perspective.&nbsp; Absolute Power is the total voltage, or energy, that the brain is emitting, measured in microvolts squared in disparate frequencies. Relative Power is a measure of clients’ EEGs, viewed in relation to their absolute power profile, used to determine what may be deviant, in relative terms. Magnitude is measured in pure microvolts.</p><p>A measure of clients’ EEGs, viewed in relation to their absolute power profile, used to determine what may be deviant, in relative terms.&nbsp; Coherence is the stability of phase relationship between any two areas of the brain. Two areas are said to be coherent if they have constant respective relative phase. Coherence in excess is hypercoherence; coherence in deficiency is hypocoherence. Phase is any one point or portion in a recurring series of changes, as in the changes of motion of one of the particles constituting a wave or vibration; the metrics of phase are very similar to coherence.</p><p>When reading a Z-score map, 1.64 standard deviations is considered the threshold of clinical significance.&nbsp;</p>