Eyes Closed vs. Activation Database Approach
One of the approaches relied upon historically in the field is use of eyes closed data to determine protocol interventions. In this situation the subject sits in a chair with their eyes closed and the qEEG data is collected. The subject is requested not to go to sleep or to think of anything in particular. The frequency range typically is not collected above the 32 Hertz range. The assumption behind this approach is that under task conditions the patterns will remain roughly the same and that deficits observed under the eyes closed condition will be present during the activation condition. This assumption has some value with children, but loses validity with adults (over age 14).
In the activation condition, the subject undergoes cognitive challenges which are particularly difficult, in order to avoid a ceiling effect. A ceiling effect occurs when the items are so easy that everyone is able to successfully accomplish the task and thus it is impossible to distinguish between who is a good performer on the task and who is not. The activation database employs a frequency range up to 64 Hertz, which offers considerable advantages in certain clinical situations.
A specific clinical example may help elucidate this difference. The following figure presents the results of the eyes closed data analysis. In this situation the results indicate high levels of delta and theta and low coherence values in the delta and theta frequency range.