Quickamp amplifier system

The laboratory surveys took place in a sound- and magnetic field-isolated cabin from 03.05. to 02.07.2021 on the campus of the University of the Bundeswehr in Munich. Measurement times were between 8.00 a.m. and 3 p.m. Electrophysiological data was recorded using a 72 channels QuickAmp amplifier system (BrainProducts GmbH, Munich, Germany). EEG was measured with a 64-channel ANT Waveguard electrode cap (ANT B.V., Enschede, The Netherlands) with active shielding and Ag/AgCl electrodes, which were arranged according to the international 10/10 system. Vertical electrooculograms (EOGs) were recorded above and below one eye. Electrode impedances were kept below 10 kΩ. Data was sampled at 250 Samples/s in a range from DC to 70 Hz with a notch filter at 50 Hz. Data was acquired during a task-free resting state with eyes closed and eyes open for a duration of 3 min each.

All participants were measured with the same equipment. During all sessions, physiological data were recorded with a 72 channels QuickAmp amplifier system (BrainProducts GmbH, Munich, Germany). EEG was measured using a 64 channels ANT electrode cap with active shielding and Ag/AgCl electrodes which were arranged according to the international 10/10 system. The system was grounded at the participants' shoulder. Data were recorded at a sampling rate of 250 Hz and 22 bit resolution with a common average reference and filtered in a range from DC to 70 Hz. For correction of eye movement and blink artifacts, the vertical electrooculogram (EOG) was measured by placing two electrodes above and below one eye. Respiration was measured with a respiration belt and skin conductance at the second and third finger of the non-dominant hand. Additionally, for measuring heart rate variability, the electrocardiogram (ECG) was assessed with two more electrodes. The experimenter was monitoring the raw data during the recording. Due to meditators residing in different countries, the measurements were carried out at various locations, predominantly in rooms normally used for meditation or in the participants' homes.