Spike vs electrode artefact v2

 The following two images of the same page, viewed on different montages, illustrate the problem discussed in the previous post,  emphasising rule 2.

in the image above, while the patient is asleep, there appear to be theta waves and low amplitude spikes at T6. However, they do not involve adjacent electrodes.

 when viewed on the bipolar montage, electrode artifact at T6 becomes apparent (the trace moves in opposite directions

This is a different page from the same patient, illustrating the point above again. Notice the wave on the left-hand side of the page below. Ask yourself what you would have thought of the waves had you only seen the referential montage. By the way, this is one of the several significant disadvantages of the referential montage.