Brainamp dc

Reaction time (RT) was defined as the time between pattern onset and button press, as long as it did not exceed the inter-stimulus-interval. In accordance with signal detection theory, a button press in response to a deviant pattern (target) was treated as a hit, whereas a button press in reaction to a standard pattern (non-target) was registered as a false alarm. Discrimination sensitivity (d’) between standard and deviant patterns was estimated using the log-linear correction [61 (link)].
EEG data was recorded continuously at 64 Ag/AgCl active electrodes, mounted according to the 10–10 international system in a suitable head cap, and amplified with a BrainAmp DC (Brain Products GmbH, Germany) amplifier and digitised with a sampling rate of 500 Hz. Eye movements (EOG) were measured horizontally with two electrodes positioned at the outer canthi of the eyes and vertically with one electrode below the left eye which was bipolarised with Fp1. Impedances were kept below 5 kΩ at all electrodes.

Individual T1 weighted structural MR images (Phillips 3.0T Ingenia MR system, Philips Healthcare, The Netherlands) were obtained from each participant for spatial navigation to precisely locate the cortical target for TMS stimulation. For neuro-navigation we used the PowerMag View! system (MAG & More GmbH, München, Germany). This system uses two infrared cameras (Polaris Spectra) to track the position of the participant’s head and TMS coil in space. A figure-eight coil (Double coil PMD70-pCool, MAG & More GmbH, München, Germany) was used for stimulation (maximum field strength of 2T (~ 210 V/m), pulse length of 100 μs, winding diameter of 70mm, biphasic pulse form) driven by a PowerMag Research 100 stimulator (MAG & More GmbH, München, Germany). The RMT was determined using PowerMAG Control (MAG & More GmbH, München, Germany). EEG was recorded with two 32-channel TMS-compatible amplifiers (BrainAmp DC, Brain Products, Germany) connected to a 60 channel TMS-compatible EEG cap. In addition, two electrodes detected eye movements (EOG), and a common reference was positioned at the forehead with the ground electrode. The impedance of all EEG electrodes was kept under 10 kΩ. EEG signals were sampled at 5000 Hz with 16-bit resolution and a 1000 Hz low pass filter was applied upon acquisition.

Visual stimuli were presented through a RDT231WM-X monitor (Mitsubishi, Japan) and were controlled by PsychoPy version 1.83 [28 (link)]. EEG data were collected using BrainAmp-DC and ActiCap with 32 channels (Brain Products, Munich, Germany) at standard locations following the extended 10/20 international system referenced to the nose and grounded to the forehead. The sampling rate was 500 Hz, and the impedance was kept below 25 kΩ. The EEG filtering parameter was set to dc-to-70 Hz (12 dB/oct). All EEG data were recorded in a soundproof room using Brain Vision Recorder software from Brain Products.

During the experiments, EEG signals were recorded using 32 wet electrodes positioned over an actiCAP (Brain Products GmbH, Germany). Two additional electrodes, serving as ground and reference, were located on the ear lobes. Electrodes were placed following the 10–10 distribution, with four electrodes used for recording electrooculography (EOG), arranged in a cross shape with respect to the eye with the vertical ones around the left eye. The data were wirelessly transmitted using a WiFi MOVE unit (Brain Products GmbH, Germany) and amplified with BrainAmpDC (Brain Products GmbH, Germany).
The REX exoskeleton (Rex Bionics, New Zealand) was utilized for the experiments. This exoskeleton is capable of independently supporting both itself and the weight of the subject, making it suitable for individuals with complete spinal cord injury. It is comprised of powered hip, knee and ankle joints (bilaterally). This self-standing exoskeleton does not require crutches and can be controlled by high-level commands sent via Bluetooth to initiate or stop the gait. Real-time feedback on the exoskeleton status was also provided during the experiments. Figure 1 shows the equipment employed in the experiments.Fig. 1

Equipment employed in the experiments

Following the procedures described in Barraza et al. (2019) (link) for the implementation of the EEG hyperscanning setup, the EEG signals of the two participants were simultaneously recorded with two 32-channel BrainAmp DC amplifiers with an actiCap system (Brain Products GmbH). Each subject was connected through an individual Electrode Input Box to one amplifier, which allows for individual Reference and Ground electrodes. Each BrainAmp DC amplifier was battery-powered and coupled using a USB interface (BUA). Signals from the two participants were synchronously recorded in a 64-channel workspace of the BrainVision Recorder software. The data were continuously acquired during the whole experiment. The electrodes were placed at the standard positions based on the extended international 10–20 system. Ground electrodes were placed at AFz location and online reference at channel FCz. Electrode impedances were kept below 10 kΩ. The EEG was filtered online from 0.01 to 100 Hz with a sampling rate of 1000 Hz.

We measured STN LFPs from temporarily externalised DBS wires (4 electrode sites per lead) sampled at 5 kHz by a BrainAmp DC (Brain Products GmbH, Gilching, Germany) EEG recorder. A ground and a reference scalp EEG input were placed over the central midline region C_z (according to the international 10/20 system) and connected to the EEG recorder. All electrode impedances were < 5 kOhm and signal quality was checked visually for electrode or movement artefacts. All experiments were performed in a sitting or supine position such that patients were able to see the computer screen providing visual feedback. As a baseline condition, we first recorded a resting state condition in which patients looked at a blacked monitor for 60 s. Using the BrainVision Recorder and Analyzer (both from BrainProducts GmbH, Gilching, Germany), we then identified the pair of adjacent electrode contacts in the STN contralateral to the PD-dominant hand that showed the highest beta power in the power spectral density and determined the beta-peak frequency as an individual parameter to be used for signal processing^{11 (link)}. For patients 1, 8 and 10, the PD-dominant hand was the left, while for all others the PD-dominant hand was the right.

EEG was recorded from 32 electrodes placed according to the International 10–20 system, using active Ag/AgCl electrodes (ActiCAP), Brain Amp DC, and Brain Vision Recorder software (Brain Products GmbH, Germany). The FCz electrode was used as the on-line reference. Electro-oculogram (EOG) was recorded from electrodes above (Fp1) and below the eye, and at the outer canthi of the eyes (F9, F10). The recorded EEG electrodes were F7, F3, Fz, F4, F8, FC5, FC1, FC2, FC6, T7, C3, Cz, C4, T8, TP9, CP5, CP1, CP6, TP10, P7, P3, Pz, P4, P8, PO9, and Oz. The data were recorded with a sampling rate of 500 Hz and were filtered on-line with a time constant of 10 s and a high cutoff at 1000 Hz. Electrode impedances were typically kept below 25 kΩ.