The performance of electroencephalogram (EEG) recordings is affected by electrode type, electronic parameters such as filtering, amplification, signal conversion, data storage; and environmental conditions. However, no single method has been identified for optimal EEG recording quality in all situations. Therefore, we aimed to provide general principles for EEG electrode selection as well as electronic noise reduction, and to present comprehensive information regarding the acquisition of satisfactory EEG signals. The standards provided in this document may be regarded as Korean guidelines for the clinical recording of EEG data. The equipment, types and nomenclature of electrodes, and the details for EEG recording are discussed.

Citations

• Basics of Electroencephalography for Neuropsychiatrist
  Hun Jeong Eun
  Journal of Korean Neuropsychiatric Association.2019; 58(2): 76.     CrossRef

Background
: Posterior tibial nerve somatosensory evoked potentials (PTSEP) have cortical potentials on primary sensory area of foot around 40 msec. The direct cortical recordings of the cortical potentials shows high voltage positive wave on medial hemisphere, especially on paracentral lobule (PCL). However, it is so diffcult to record the potential directly on PCL that the cortical potential of PTSEP is not well understood. We investigated the cortical potential of PTSEP on subdural electrodes. Methods : We recorded cortical potentials to posterior tibial nerve stimulation on subdural electrodes which were on medial hemisphere near PCL in 15 intractable neocortical epilepsy patients. The numbers of subdural electrodes were 8 in 10 subjects(1x8 array) and 16 in 5 subjects (2x8 array). Seven subjects had three-dimensional imaging fusion (3D-fusion) of MRI and the electrodes using Analyze program. We investigated the amplitude, latency, polarity, and phase of the waves regarding location. Results : The wave had maximal amplitude on PCL in 4 subjects, precuneus in 1, cingulate gyrus nearest to PCL in 2 among 7 subjects with 3D-fusion. Also the electrodes were located on posterior area of PCL (2 out of 2 subjects with more than two electrodes put on PCL in 3D-fusion) and superior area of it ( 5 out of 5 subjects with 2x8 arrays). All the high (more than 20 uV) amplitude around 40msec had positive polarity in 7 subjects. The phase reversals were detected between the electrodes with the highest amplitude and the just posterior (2 subjects) or anterior (6 subjects) located electrodes. The just posterior located electrodes had sharper phase reversal than the anterior one. Conclusion : PTSEP might have maximal amplitude of cortical potentials on the more superior and posterior area of PCL. The highest amplitude potential has positivity. The wave with maximal amplitude could have phase of cortical potentials with surrounding electrodes, especially shaper with posterior part than with anterior one.

and others underwent flash goggle VEPs. Results : Brain imaging were abnormal in 29 and were normal in 2. Of the 29 abnormal scans, lesions in posterior visual pathway were detected in 21 scans(predictive value=68%). The predictive value ws not significantly different between flash goggle VEP(75%) and pattern reversal VEP(68%). The predictive value was higher in patient with visual field defect(100%) than those without visual field defect(25%). The pathologic nature of lesion also showed close relations to the predictive value. VEPs is usually paradoxically lateralized(78%), but in all patients. Conclusion : VEPs abnormalities suggesting retrochiasmal lesion were usually corresponded with brain MRI findings. Diagnostic reliability could be increased when considering the visual field defect and nature of lesion. Therefore, the authors suggest that VEPs studies could be useful in evaluating the patients with the retrochismal lesion.

Background
Background: In belly-tendon (bipolar) montage, reference (R2) electrode placed on muscle

Background
A dry-type electrode is an alternative to the conventional wet-type electrode, because it can be applied withoutany skin preparation, such as a conductive electrolyte. However, because a dry-type electrode without electrolyte has highelectrode-to-skin impedance, an impedance-converting amplifier is typically used to minimize the distortion of the bioelectricsignal. In this study, we developed an active dry electroencephalography (EEG) electrode using an impedance converter, andcompared its performance with a conventional Ag/AgCl EEG electrode. Methods: We developed an active dry electrode withan impedance converter using a chopper-stabilized operational amplifier. Two electrodes, a conventional Ag/AgCl electrodeand our active electrode, were used to acquire EEG signals simultaneously, and the performance was tested in terms of (1)the electrode impedance, (2) raw data quality, and (3) the robustness of any artifacts. Results: The contact impedance ofthe developed electrode was lower than that of the Ag/AgCl electrode (0.3