What is the primary benefit of achieving balanced impedances in EEG recording?

Achieving balanced impedances in EEG recording is primarily beneficial for maximizing common mode rejection. When the impedances across electrodes are equalized, it ensures that the electrical signals picked up by each electrode are more comparable. This uniformity allows the amplifier to effectively differentiate between the desired brain activity (which is a common signal across multiple electrodes) and unwanted noise or interference (which often appears differently across electrodes).

By maximizing common mode rejection, the EEG system can better suppress artifacts and noise that can distort the recorded signals, leading to clearer and more accurate representations of brain activity. This is critical for following accurate clinical interpretations and ensuring reliable data collection during EEG studies. Achieving and maintaining balanced impedances is therefore a key practice in EEG preparation and recording procedures.