Abralyt hicl

The cEEGrid recording procedure was identical for both original studies. For better electrode to skin conductance, the skin around the ears was prepared with abrasive gel (Abralyt HiCl, Easycap GmbH, Hersching, Germany) and cleaned with 70% alcohol. Thereafter, a small amount of abrasive gel was placed on the cEEGrid electrodes (TMSI, Oldenzaal, Netherlands; Debener et al., 2015 (link)) before it was attached with double-sided adhesive around the ear. Impedances were kept below 20 kΩ. Each participant was equipped with two cEEGrids, one around the left and one around the right ear. Electrodes R4a and R4b of the right cEEGrid served as ground and reference, respectively (Figure 1B). The two cEEGrids were connected to a 24-channel mobile amplifier (SMARTING, mBrainTrain, Belgrade, Serbia) which transmitted the data via Bluetooth to a recording computer. The cEEGrid data were acquired with a sampling rate of 500 Hz. The transmitted cEEGrid data as well as the onset markers of the 10-min blocks were integrated using the Lab Recorder software based on the Lab Streaming Layer¹ to time synchronize these data streams (Mullen et al., 2015 (link)).

EEG was recorded from 64 scalp electrodes, positioned according to the international 10–20 system using a TMS-compatible amplifier (Bittium, NeurOne, Bittium Corporation, Finland) with a sampling rate of 2 KHz. The scalp electrodes site included Fp1, Fp2, F7, F3, Fz, F4, F8, FC5, FC1, FC2, FC6, T7, C3, Cz, C4, T8, FPz, CP5, CP1, CP2, CP6, PO9, PO5, P7, P3, Pz, P4, P8, FCz, O1, Oz, O2, AF7, AF3, AF4, AF8, F5, F1, F2, F6, TP9, FT7, FC3, FC4, FT8, TP10, C5, IZ, PO10, C6, TP7, CP3, CPz, CP4, TP8, P5, P1, P2, P6, PO7, PO3, POz, PO4, and PO8 and were mounted on the head with a cap (EASYCAP, Herrsching, Germany). The reference electrode was positioned on FCz, and the ground electrode was placed at the AFz. The electrodes were connected to the head using high-viscosity electrolyte gel (Abralyt HiCl, EASYCAP, Herrsching, Germany). All impedances were kept below 5 kΩ throughout the experimental sessions. During EEG recording, participants were asked to wear noise canceling headphones on top of earphones playing a noise specifically designed to mask the TMS click [28 (link)]. Raw EEG data were recorded and stored for offline analysis.