|
| Frequently Asked Questions |
| 1- How do you know that
the Lexicor, Mindset, DeyMed, Mitsar, BrainMaster, etc. Amplifier
characteristics match the ampliferier characteristics of the
normative database? 2- What units are the Current Source Density norms in and why do you need 19 channels? 3- Are there any free updates to NeuroGuide? 4- What operating systems does NeuroGuide run under? 5- Does NeuroGuide Generate a Clinical Report? 6- Does NeuroGuide Compute Comparative Statistics such as Pre vs. Post Treatment etc. and/or Group Comparison Statistics? 7- How is LORETA Implemented by NeuroGuide? 8- How do you do the Artifacting to Patch Together Small Segments of EEG? 9- How Can NeuroGuide help in evaluating EEG using BrainMaster or CapScan or ProComp? 10- Does NeuroGuide Acquire EEG or Evoked Potentials? 11- Reserved for Future questions 12- Reserved for Future questions 13- Reserved for Future questions 1- How do you know that the Lexicor, Mindset, DeyMed, Mitsar, BrainMaster, etc. Amplifier characteristics match the ampliferier characteristics of the normative database? We inject microvolt calibration signals of different amplitudes and frequencies into the input of the respective EEG machines. We then compute correction curves to exactly match the amplifier characteristics of the norms and discriminant functions. The units of comparison are in microvolts and a match within 3% is generally achieved. We double check the amplifier match by computing FFT and digital spectral analyses on calibration signals used to acquire the norms with the calibration signals used to evaluate a given manufacturers amplifiers. Back to Top 2- What units are the Current Source Density norms in and why do you need 19 channels? We use the Laplacian spherical harmonic method to compute current source density as described by Pascual-Marqui et al, (Int. J. Neurosci., 43: 237-249). Current source density is represented in microamps (ua) and not microvolts. This methodology is superior to the Horth method and it is not influenced by edge effects (e.g., T3/4, T5/6, etc.). However, it does require 19 channels in order to estimate the current source density. Back to Top 3- Are there any free updates to NeuroGuide? Yes, new EEG formats are free updates in NeuroGuide Deluxe and we are regularly improving and adding new features and better user friendly options. Back to Top 4- What operating systems does NeuroGuide run under? Windows NT, 95, 98, ME, 2000, XP, Vista run with the current NeuroGuide. Back to Top 5- Does NeuroGuide Generate a Clinical Report? No. NeuroGuide produces tab delimited text files of a patient's spectral values and Z scores and color maps. NeuroGuide is designed for use by a qualified professional in EEG/QEEG who is trained to export numbers to Worksheets like Excel, Statistic programs and databases liken Access and other database programs. Send your raw unedited EEG samples to: qeeg@appliedneuroscience.com for expert clinical neurophysiological evaluation. Back to Top 6- Does NeuroGuide Compute Comparative Statistics such as Pre vs. Post Treatment etc. and/or Group Comparison Statistics? Yes, by the use of the add on product called NeuroStat ($500) one can easily compute absolute differences and percent differences with topographic color maps and tab delimited outputs that are ready for publication. NeuroStat also computes repeated measures analysis of variance (ANOVA) and paired t-tests as well as correlations and R square (percent variance accounted for) in a format that is ready for publication. NeuroStat will in the future, as a free upgrade, compute eyes open vs. eyes closed difference Z scores including 1 Hz topographic color maps and tab delimited output. Automatic analysis and Group comparisons of hundreds of subjects are accomplished by the add-on program called NeuroBatch ($200) which allows users to create NeuroGuide output files in batch mode as well as group means and standard deviations which can be imported into NeuroStat to compute 1 Hz topographic color maps and tab delimited ascii output (NeuroBatch is expected to be released in October 2004), free updates of NeuroBatch and NeuroStat are included with all 2003 purchases. Back to Top 7- How is LORETA Implemented by NeuroGuide? NeuroGuide Deluxe exports frequency domain and time domain edits of 19 channel x 256 point digital EEG in microvolts (or uv^2) in the Lexicor electrode order and using the Key Institute T-Matrix. Rows are the 256 microvolt time points and the columns are 19 channels at a sample rate of 128 thus producing 0.5 Hz resolution from 1 to 30 Hz. The frequency domain cross-spectra are automatic and can be launched by a single mouse click. Manual time series ASCII files are also exported to the Key Inst. LORETA programs. The time domain exports are especially optimized for import using the "EEG cross-spectra > A1EEGs -> 1Spec(aut)" option, which computes 1 single cross-spectral file for each 256 time point. The exported ASCII values can be used as scalar multipliers of the 'T' matrix as computed by the Key Institute software which is free to down load from http://www.unizh.ch/keyinst/NewLORETA/Software/Software.htm. The step by step procedures to link NeuroGuide to the LORETA-Key software is described in the NeuroGuide Manual. The competent use of LORETA is not easy to learn, it does require advanced training and experience. For educational purposes, NeuroGuide provides cross-spectral and time domain ASCII output files from the same samples of EEG as well as calibration sine waves from the NeuroGuide Signal Generator program so that a user can mathematically and physiologically validate LORETA for themselves. One such validation is a Eyes Open vs. Eyes Closed alpha EEG validation of LORETA which is recommended for the users of LORETA. The digital EEG or the alpha frequency spectra should be localization in posterior cortex and reduced LORETA posterior alpha currents are expected in the Eyes Open condition relative to the Eyes Closed condition. An Eyes Open vs. Eyes Closed LORETA validation procedure is illustrated in the NeuroGuide Users Manual. The NeuroGuide Signal Generation program is also useful to validate LORETA by mathematical simulation of the EEG. NeuroGuide provides easy access and a gateway to this new world of 3-D electrophysiology so that any user of NeuroGuide by visual examination of the EEG/EP scalp distributions and knowledge of known anatomical and physiological properties can validate LORETA and other inverse solutions using NeuroGuide exports. Back to Top 8- How do you do the Artifacting to Patch Together Small Segments of EEG? We achieve stable and reproducible FFTs in three steps: 1- splice together EEG segments to form 2 second epochs of EEG (gives 0.5 Hz resolution and 256 points, minimum segment length = 800 msec), 2- filter to remove any high frequencies due to the splicing and 3- use sliding averages of overlapping 64 point windows (75% overlap as Kaiser and Sterman, J. Neurotherapy, 2001). We experimented with different overlapping windows and different filters and we computed the cross-validated Z scores for each of these experiments. We essentially replicated Kaiser and Sterman's method to reduce window effects and we achieved quite reliable results no matter what the splice segment lengths with overlapping of the 2 second epochs of EEG for both the normative EEG samples and patient EEG samples. Tests using the worst case scenario of segment splicing of the troughs and peaks of sine waves revealed side band ringing in the FFT which was maximally about 3% of the signal. This worst case scenario is never obtained in practice and the effects of splicing are < 3% by limiting the minimal segment length to 800 msec and by filtering. When filtering and 800 msec. segments are used, then the side band ringing is not measurable. The users of NeuroGuide can compare for themselves the effects of windowing in the FFT by comparing the ASCII FFT spectral values for overlapping vs. non-overlapping FFTs. Click on the menu Analysis>LORETA Export>Overlapping Windows and save. Repeat by clicking Analysis>LORETA Export>Successive in order to save non- overlapping FFTs of the same data. Back to Top 9- How Can NeuroGuide help in CPT Code billing using BrainMaster or CapScan or ProComp? NeuroGuide is a standalone software program that is intended for research and education. NeuroGuide provides a suite of analytical tools that allows for spectral analyses of EEG samples from 1 to 19 channels from EEG machines that have been calibrated using standardized sine waves. The research and educational tools in NeuroGuide allow the user to probe more deeply into the dynamic structure of the electrical activity of the brain and to perform statistical analyses with a few mouse clicks. Back to Top 10- Does NeuroGuide Acquire EEG or Evoked Potentials? Yes, NeuroGuide can acquire EEG and Evoked Potentials using the Mindset amplifiers. The acquisition module is sold only with NeuroGuide Deluxe or NeuroGuide for Mindset for $500 extra. Back to Top 11- Reserved for Future questions Back to Top 12- Reserved for Future questions Back to Top 13- Reserved for Future questions Back to Top |
Mindset
24 Channel QEEG Clinical System (Only $4995!) | Impedance
Tester | Electro-caps
for QEEG | Mindset Calibrator