If the exploring and reference electrodes are close to one another, what happens to the amplitude?

When exploring and reference electrodes are positioned close to one another, the amplitude of the recording generally decreases. This is attributed to the phenomenon known as the "volume conduction effect." When electrodes are too close, they pick up similar electrical signals from the underlying tissue, which reduces the differences in the potential readings. This leads to a lesser amplitude because the signals from each electrode cancel each other out to some extent, resulting in a reduced net signal.

In contrast, when electrodes are placed further apart, the likelihood of capturing distinct signals increases, which can enhance the amplitude of the recorded potential. Therefore, the positioning of electrodes is critical in polysomnography as it can significantly impact the quality and clarity of the data obtained.