Presented by Jeff Tarrant: To date, EEG mapping for assessment has been typically done using population-static z-scores, and EEG neurofeedback using live z-scores has used population-dynamic z-scores. In both cases, population means and standard deviations are being used as the references. This raises fundamental concerns when it is recognized that individuals are unique, and using a population-based statistic has the undesirable result of causing every subject to be compared to a group, raising concerns about the validity of these measurements.
This workshop describes and briefly characterizes a method for computing quantitative EEG (QEEG) z-scores based on a modification of the typical methods used for QEEG reporting. In particular, it describes using a sample of EEG from a single individual, and creating a reference database from the individual sample. The goal of this method is to quantify and localize within-subject changes, providing the ability to compare an individual to themselves at a different point in time. The resultant z-scores of this comparison provide a concrete measure of any significant changes from time 1 to time 2. These measurements can be calculated for all frequency bands, at all scalp locations, sLORETA voxels, and sLORETA Regions of Interest (ROIâ€™s). In addition, this information can be displayed on a 3D brain image, allowing the user to visualize the changes.
We refer to this approach as â€œz-builder,â€ because the z-score reference is constructed or â€œbuiltâ€ on a per-subject basis in the office or laboratory, and is not derived from a reference obtained from an outside source. This individual database can be used to examine state changes as a result of time, medications, or some other intervention. The individual database can also be used in z-score neurofeedback to train an individual toward a desired state which has been previously recorded.
In this workshop, we will present preliminary evidence that this approach is valid and statistically sound. We will present a variety of case studies that demonstrate the stability of individual EEG scores in the absence of intervention, as well as changes resulting from meditative states, vibroacoustic stimulation, virtual reality, and microdosing psilocybin. In addition, we will discuss the process of using z-builder neurofeedback applications for achieving specific peak states or improved cognitive functioning.