Use CBL205-MRI when more than one ground is required while recording electrodermal activity (a.k.a. galvanic skin response). To record EDA with other biopotential signals (ECG, EEG, EOG, EGG, EMG, ERS), BIOPAC recommends using CBL205-MRI connected to one ground on any of the biopotential amplifiers. The subject will be grounded through the Vin- of the EDA electrodes, but in some cases it is necessary to have more than one ground; in such cases, use an AC-coupled lead adapter (CBL205-MRI) to prevent galvanic ground loops. For example, if—while recording a biopotential and EDA—the EDA electrode is removed during a stage of the experiment, you will want to maintain ground for the biopotential. To always have a ground and no ground loops: connect the Vin- lead of the EDA as ground and connect an AC-coupled ground to the biopotential amplifier GND.
Safety Note—If using any two EDA100C-MRI or NICO100C-MRI modules at the same time on the same MP System, ground loops can be a problem due to non-isolation between module excitation currents. A possible solution is to record with one module connected to a separate IPS100C and HLT100C, and the remaining module to the MP System. Use OUTISO signal isolators to connect the first module outputs (via HLT100C) to the UIM100C on the MP System side.