There are a few things that can be done to optimize the settings for EEG recording in cases where the quality of the EEG recording might be suffering.
One problem that can occur with EEG recording will be a wandering baseline, or movement of the EEG signal away from 0V. If this occurs, it can affect the users ability to see the signals well (which may only be as much as 50uV in amplitude). To remedy this, make sure that wherever the electrodes are placed, specifically the ground electrode, that it is on a more bony part of the head. This means that if it is placed behind the ear, you should find the bone protrusion behind the ear (mastoid process) for proper electrode placement. If electrodes are on a more fleshy part of the head, the signal will be a bit more unstable.
Another issue might be a low resolution, or improper range. The default range in the EEG Experiment Settings file is set at 20mV. Because the signal may often be much smaller than that, lowering the range to something closer to the amplitude of the signal of interest (100uV) may result in a higher quality recording.
Good electrical contact of the electrodes to the skin is another driver of EEG signal quality. Proper skin preparation should be a focus, as well as utilizing proper electrodes. For use with ADInstruments Equipment, the MLAWBT9 EEG Flat Electrodes
are a quality choice for electrodes, along with the MLA1095 Electrode Paste
. If an electrode impedance or contact issue is suspected, users can ensure a quality connection by utilizing the MLE2002 Model 1089 MK III Checktrode.