Brainamp exg mr

EEG was recorded using an MR-compatible EEG cap (Braincap MR, Easycap, Herrsching, Germany) with 64 ring-type electrodes and two MR-compatible 32-channel amplifiers (Brainamp MR plus, Brain Products GmbH, Gilching, Germany). EEG caps included 62 scalp electrodes referenced to FCz. Two bipolar ECG recordings were taken from V2-V5 and V3-V6 using an MR-compatible 16-channel bipolar amplifier (Brainamp ExG MR, Brain Products GmbH, Gilching, Germany). Using high-chloride abrasive electrode paste (Abralyt 2000 HiCL; Easycap, Herrsching, Germany), electrode-skin impedance was reduced to < 5 KOhm. To reduce movement-related EEG artifacts, subjects' heads were immobilized in the head-coil by surrounding the subject’s head with foam cushions. EEG was digitized at 5000 samples per second with a 500-nV resolution. Data were analog filtered by a band-limiter low pass filter at 250 Hz and a high pass filter with a 10-sec time constant corresponding to a high pass frequency of 0.0159 Hz. Data were transferred via fiber optic cable to a personal computer where Brain Products Recorder Software, Version 1.x (Brain Products, Gilching, Germany) was synchronized to the scanner clock. EEG was monitored online with Brain Products RecView software using online artifact correction.

Simultaneously with fMRI acquisitions, we recorded scalp-surface EEG using a 64-electrode cap (BrainCap MR; Brain Products; referenced to FCz) and electrocardiography using 3 bipolar electrodes (Brain Products). Electrode–skin impedance was kept below 5 kΩ (plus 10 kΩ built-in resistors) using abrasive paste (Nuprep; Weaver and Company) and electrode gel (Electro-gel; Electro-cap International) to ensure stable data acquisition throughout the recording session. EEG data were recorded with two 32-channel amplifiers (BrainAmp MR plus, Brain Products) and ECG data with one 16-channel amplifier (BrainAmp ExG MR, Brain Products). Data were analog-filtered (0.016–250 Hz) and digitized (5 kHz sampling rate; 500 nV resolution) with BrainVision Recorder 1.20 (Brain Products).
fMRI time series were acquired in a 3.0-T scanner (Magnetom TIM Trio, Siemens) with an echo planar imaging sequence (voxel size = 3.4 × 3.4 × 3.0 mm; 32 transversal slices; [TR] = 2460 ms; [TE] = 40 ms; flip angle = 90°; [FOV] = 220 mm). A structural T1-weighted image was also acquired with a MP-RAGE sequence (voxel size = 1.0 × 1.0 × 1.0 mm; 176 sagittal slices; TR = 2300 ms; TE = 2.91 ms; flip angle = 9°; FOV = 256 mm).

To exclude involuntary writing or drawing during the MI tasks we recorded the muscle activity using an MRI compatible electromyogram (EMG) (BrainAmp ExG MR, Brain Products GmbH, Gilching, Germany) with two adjacent surface electrodes on the flexors and two on the extensors of the right forearm, resulting in two EMG-derivations, one for each of the corresponding muscular compartments of the forearm. The EMG signal was recorded using BrainVision Recorder and observed online via BrainVision RecView (Brain Products GmbH, Gilching, Germany). In addition, an online observation of the muscle activity was realized via the BrainVision RecView (Brain Products GmbH, Gilching, Germany).

We measured EDA with BrainAMP ExG MR, Acceleration Sensor (Brain Products,
www.brainproducts.com), and Ag/AgCI sensor
electrodes (Model F-EGSR, Grass Technologies). The signal was recorded with
Brain Vision Recorder (Brain Products) at a sampling rate of 5000Hz for the
first 8 participants and 1000Hz for all others, with low cut-off DC and high
cut-off 1000Hz. The reason for decreasing the sampling rate was to reduce
unnecessary memory requirements and processing time in the data analysis as we
were not interested in high-frequency components of the EDA signal. No other
filters were applied to the signal. Sensor electrodes for EDA were placed at the
middle phalanx of the index and middle finger of the non-dominant hand (right
hand for 4 people).
Questionnaire data were acquired with pen and paper, and later digitized
manually.