qEEG-Pro Report Generator
qEEG Pro Quick Guide
A quick guide on how to navigate the qEEG Pro software
Classical Power Analysis
- Absolute Power
- Relative Power
- Amplitude Asymmetry
Burst Metrics
The analysis of Burst activity is calculated in several steps. First, the second derivative of the power in 9 frequency bands was calculated. In this time series, peaks in power are defined by the points in time in which the value of the second derivative turns from positive to negative. After the peak power detection, bursts were identified by the evaluation of two criteria. The first criterion evaluates the duration of the full-width half-maximum (FWHM) around a peak in the power within a frequency band of interest. When the FWHM is larger than 2* and smaller than 10* the average cycle duration of the center frequency within a frequency band of interest, the first criterion is met. The second criterion evaluates the difference between the power at the start of the burst period and the peak power of the burst period. When this difference exceeds the median band power + 1* the standard deviation, the second criterion is met.
Extreme Z-Score Development
For 9 frequency bands the frequency is analyzed in which the most extreme Z-score is found.
Comodulation
Power fluctuations within the recording of each 1 Hz bin are correlated with the whole frequency spectrum (1-40 Hz). The resulting heatplot represents the correlations between all 40 X 40 possibilities. The red diagonal line that is present in all of these heatplots represents the correlations between identical power bins, which are always 1. As a reference, the Alpha Peak Frequency is marked with a white cross (Eyes Closed condition only).
Alpha Peak Frequency
Alpha oscillations in the EEG signal are one of the best studied phenomena in EEG literature. Alpha oscillations occur within the 8-12 Hz frequency range and can often be easily observed in raw EEG when the eyes of your subject are enclosed.
Connectivity Measures
When assessing the brain activity of a patient it is not only relevant to see what the deviations are in any particular brain area but also whether there are deviations in the communications between brain areas. QEEG Pro distinguishes three ways of assessing communication between brain areas.
Fluctuation Time
In this analysis, power fluctuations respective to the median power is calculated 9 frequency bands. Next, the average duration between two crossings of the median is calculated. By definition, the average duration above the median threshold is identical to the average duration below the median threshold. This analysis can be used to study the variability of the power for a frequency bin of interest and may function as a guide for setting the time above or below threshold criterion in Neurofeedback protocols.
Percentage Deviant Activity
In this analysis, the power fluctuations are compared with the normative database. The percentage of the time in which the z-score is above or below 2.3 is calculated. When the z-score analyses for an electrode site and frequency bin depicted on page 2 and 3 is positive, the percentage from 0 up to100 percent is scaled from green to red (0 up to 100 percent). When the z-score analyses for an electrode site and frequency bin depicted on page 2 and 3 is negative, the percentage from 0-100 percent is scaled from green to blue (0 down to -100 percent). The reason a z-score cutoff value of 2.3 was chosen is that this zscore value corresponds with a p-value of .001, which is a commonly used threshold for comparisons that are uncorrected for multiple comparisons in neuroscience literature.
