What type of artifact is indicated if there are readings from only one EEG channel?

When readings are observed from only one EEG channel, it typically indicates an electrode artifact. This scenario suggests that there may be an issue with the electrode placement, connection, or functionality. If an electrode is displaced or poorly attached, it may fail to accurately record data, leading to the appearance of activity only from the functioning electrode. This can result in a misleading representation of brain activity, whereby the data from the single channel could be either genuine or reflecting artifacts that do not occur at other electrode locations.

In contrast, physiological artifacts would involve inherent biological variations that affect the entire EEG recording rather than just one channel. Motion artifacts arise from patient movements, which would influence multiple channels simultaneously rather than being isolated to one. Environmental artifacts include external electromagnetic interference, which would also typically affect multiple channels across the system. Therefore, the isolation of readings to just one channel points clearly to an issue related to the electrode itself rather than these other possible forms of artifacts.