Mar 16, 2026
Methodology for EEG and Reference Values of the Software Analysis
- Christiyan Naydenov1
- 1Department of Neurology, Medical Faculty, Trakia University, Stara Zagora, Bulgaria
- EEG
Protocol Citation: Christiyan Naydenov 2026. Methodology for EEG and Reference Values of the Software Analysis. protocols.io https://dx.doi.org/10.17504/protocols.io.14egn5ydzg5d/v1
Manuscript citation:
Naydenov C, Yordanova A, Mancheva V. Methodology for EEG and Reference Values of the Software Analysis. Open Access Maced J Med Sci. 2022 Sep 23; 10(B):2351-2354. https://doi.org/10.3889/oamjms.2022.10751
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: March 14, 2026
Last Modified: March 16, 2026
Protocol Integer ID: 313275
Keywords: EEG methodology, EEG reference values, Normal EEG, EEG software analysis, Calibrating EEG, EEG software errors, EEG technical manual, software analysis of modern eeg equipment, eeg software analysis, frequency composition of the eeg signal, main parameters of the eeg, methodology for eeg, eeg study, modern eeg equipment, electroencephalographic study, digital eeg, eeg signal, channel digital eeg, eeg under physiological condition, eeg office of the medical faculty, eeg office, eeg, individual frequency component, ratios between the individual frequency component, determination of the reference value, electrical potentials of the brain, sampling frequency, frequency composition, statistical error, ep device, mean value, reference value, software analysis, probability of statistical error, amplitude
Disclaimer
This research did not receive any financial support.
Abstract
**BACKGROUND: EEG is a way of graphically recording the electrical potentials of the brain. The main parameters of the EEG are related to the ratios between the individual frequency components, their amplitude and characteristic waveforms.
**AIM: The aim of the study was to develop and describe a consistent and detailed methodology for the technical conduct of an EEG study, as well as to find the reference values of some of the most frequently derived average values of parameters from the software analysis of modern EEG equipment. TOOLKIT: The EEG office of the Medical Faculty at Trakia University is equipped with a multifunctional 31-channel digital EEG/EP device with a sampling frequency of 1000 Hz.
**METHODOLOGY: Unification of the technical implementation is necessary so that the results can be compared with the maximum cleared probability of statistical error due to controllable factors. The outlined sequential steps can serve any technical contributor.
**RESULTS: Electroencephalographic study of 100 clinically sound participants and determination of the reference values of the indicators. We have created a table with the mean values of the EEG Software Analysis.
**CONCLUSION: The frequency composition of the EEG signal includes four types of waves or rhythms: delta/0.5–3.5Hz/, theta/4–7.5Hz/, alpha/8–12Hz/ and beta/13–30Hz/. The amplitude of the EEG under physiological conditions ranges from 15 microvolts/low-amplitude/to 150 microvolts/high-amplitude/. Average limits are between 30 and 80 microvolts.
Materials
The office of electroencephalography of the Medical Faculty at Trakia University is equipped with a multifunctional 31-channel digital EEG/EP device, with the following minimum and mandatory characteristics: Channels for EEG and long-latency EP: 25; Bipolar polygraphs channels (EEG, ECG, EOG, EMG, and EP): 6; Built-in channel impedance meter with indication on the front panel of the device for the state of the electrodes in the registration process; ADC: 24 bit; frequency range for EEG channels: 0 Hz–600 Hz; Sensitivity for EEG channels: 0.01–10000000 μV/mm; possibility of cascading the channels with an additional amplifier of the same type sampling rate: 1000 Hz.
Troubleshooting
Safety warnings
Factors changing the quality of the EEG recording and the most common errors: broken or tangled cables; poor contact of the electrodes with the scalp; dirty hair or oily scalp; poor relaxation of the patient, blinking of eyes, clenching of teeth, shaking of the head; wide smearing of the contact gel or the physiological solution, which turns the electrodes into one electrode.
Ethics statement
Each healthy participant included in the database was informed in advance about the benefits and risks of EEG and have signed an informed consent.
Before start
The following preparation and implementation is required. Notifying the patient about the upcoming examination and mental preparation; providing a patient information application and an informed consent form. Restful sleep of the patient is ensured, except in cases where sleep deprivation is necessary. On the day of the examination - washed hair with soap to reduce the resistance of the contact surface. Placing the patient on the couch or in the chair and sedating to relax; explaining that it won’t hurt; familiarization with the helmet and technique; we instruct him to cooperate during the whole study and the challenge samples. Fitting the helmet - well tightened so that the electrodes do not move during the recording. Clearing the hair and placing the electrodes pre-soaked in physiological solution in standard places according to the international 10/20 system connecting the electrodes to the cables from the EEG device. Enter the passport part in the system and record it in the laboratory journal. Measure the electrode impedance and ensure that it is within the allowable limits.
EEG Methodology
Unification of the technical implementation is necessary so that the results can be compared with the maximum cleared probability of statistical error due to controllable factors. The outlined sequential steps can serve any technical contributor. The study is carried out in an electrophysiology laboratory.
The following preparation and implementation is required. Notifying the patient about the upcoming examination and mental preparation; providing a patient information application and an informed consent form. Restful sleep of the patient is ensured, except in cases where sleep deprivation is necessary.
On the day of the examination - washed hair with soap to reduce the resistance of the contact surface. Placing the patient on the couch or in the chair and sedating to relax; explaining that it won’t hurt; familiarization with the helmet and technique; we instruct him to cooperate during the whole study and the challenge samples.
Fitting the helmet - well tightened so that the electrodes do not move during the recording. Clearing the hair and placing the electrodes pre-soaked in physiological solution in standard places according to the international 10/20 system connecting the electrodes to the cables from the EEG device. Enter the passport part in the system and record it in the laboratory journal.
Measure the electrode impedance and ensure that it is within the allowable limits. During the examination, the patient is in a soundproof, darkened room with closed eyes. Spontaneous or background activity is recorded first.
To activate changes in brain biocurrents, the following methods are applied: hyperventilation, photo stimulation, opening and closing eyes, recording during sleep deprivation, recording during natural sleep, mind counting; recording duration of at least 20 min with artifact-free epochs at 15–30 mm/s.
During the recording, the patient is actively monitored, the quality of the recording is also monitored, and if there are problems, the recording is interrupted until they are eliminated, and then continued.
Protocol references
1. Medical Standard "Nervous Diseases", 02/06/2014, "Nervous Diseases". Available from: https://www.mh.government.bg/media/filer_public/2015/11/18/nervni-bolesti.pdf (government.bg)
2. European Charter of Patient Rights, 2015. Available from: https://www.mh.government.bg/bg/informaciya-za-grazhdani/prava-i-zadlzheniya-na-pacienta/evropejska-harta-za-pravata-na-pacientite/ (government.bg)
Acknowledgements
The authors would like to thank Trakia University. The authors have declared that no competing interests exist. Open Access: This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0)
The authors would like to thank Trakia University.
Authors Contributions
Christiyan Naydenov – constructing and processing the research; writing, revising and releasing the article; exam the patients, taking the ICF, processing the EEGs; Antoaneta Yordanova - creating the database and processing the statistics; language edition; Velina Mancheva – scientific supervisor, team coordinator; final approval.
Data Availability Statement
The datasets generated and analyzed in the current study are available from the corresponding author on reasonable request.