EEG and Brain Connectivity: A Tutorial - Bio-Medical Instruments, Inc.

Multiple frequencies and multiple metrics may be selected in which a
threshold must be reached before a visual and/or auditory reward is given
(e.g., Z < 2.0). The 19 channel Z score approach provides for seamless
integration of QEEG assessment and 19 channel Z score neurofeedback or
treatment. Because there are approximately 8,000 possible instantaneous Z
scores, it is important to limit and structure the biofeedback protocol in a
manner that best links to the patient’s symptoms and complaints. The
linkage of patient’s symptoms and complaints as hypotheses that are
confirmed or disconfirmed by QEEG assessment are used to develop a
neurofeedback protocol. Blind and random selection of Z score metrics
runs the risk of altering “compensatory” systems and not focusing on the
weak or “loss of function” systems that are linked to the patient’s symptoms
and complaints.
The figure below shows an example of a simple 10/20 head display
for feedback where the circles turn green when threshold is met (e.g., Z <
2.0) and provides feedback about the scalp locations that are meeting
threshold.