Which artifact may be observed during an EEG recording?

In the context of EEG (electroencephalography) recordings, artifacts refer to extraneous signals that can interfere with the interpretation of brain activity. The presence of various physiological signals can indeed produce artifacts in an EEG recording.

Respiratory patterns can introduce artifacts primarily through changes in thoracic movement, which can affect the placement and quality of the electrodes. Cardiac signals are another significant source of artifact; electrical activity from the heart can be detected by the electrodes and may appear as rhythmic waveforms that can be mistaken for brain activity. Muscle tensions, such as those generated by facial muscles, can produce high-frequency noise or spikes in the EEG data.

As all these physiological signals—respiratory, cardiac, and muscular—can have an impact on the EEG recording, the presence of all these potential artifacts makes the chosen answer comprehensive. Identifying and differentiating between these artifacts and genuine brain activity is an essential aspect of interpreting EEG data accurately.