If an artifact appears only on channel 3 of a PSG recording, which electrode is likely causing the artifact?

The presence of an artifact only on a specific channel in a polysomnographic (PSG) recording suggests that the electrode associated with that channel is responsible for the artifact. In this case, since the artifact is seen only on channel 3, the electrode corresponding to that channel—identified as E2—would be the likely source of the artifact.

Electrodes E1 and E2 typically refer to specific locations on the scalp, such as those used for EEG monitoring, while M1 and M2 are usually referred to as electrodes for monitoring the chin or mentum muscle activity. Since the artifact is confined to channel 3, which corresponds to E2, it indicates that the signal captured by this electrode is being interfered with by some extraneous noise or disturbance, rather than a problem with the other electrodes (E1, M1, or M2). This is consistent with common practices in electrodiagnostic monitoring, where each channel represents a separate electrode's data, making it easier to identify and troubleshoot issues that arise from individual electrodes.