When a large amount of electrode paste is used for EEG recording, what is the impact on the recording area?

Using a large amount of electrode paste during EEG recordings can lead to an expansion of the recording area to the total scalp surface area covered by the paste. The primary function of electrode paste is to improve the conductivity between the electrode and the scalp, enhancing the signal captured from the brain's electrical activity. When more paste is applied, it creates a larger conductive area, which can potentially allow the electrodes to pick up signals from a broader region of the scalp.

This means that as more paste is applied, the effective area from which the electrodes can collect EEG data increases, thereby expanding the overall recording area. It can enhance the coverage of the scalp, making it possible to gather data from regions that might otherwise not be captured effectively if the paste were applied in smaller amounts. This results in a more comprehensive representation of the brain's electrical activity across a wider area.

In contrast, excessive paste may lead to complications with impedance, background noise, or signal quality. However, the defining effect here is the physical expansion of the recording area due to the larger volume of conductive medium.