Interpret the tracing in context of wakefulness, drowsiness, and visual exploration, because the same pattern can be normal in one state and misleading in another. Asymmetry or absence of an expected hyperventilation response deserves closer scrutiny.

Mu rhythm over C3-C4 can be mistaken for alpha because it shares the same frequency range; Sleep spindles and K complexes are typical of stage N2 sleep; Lambda waves and POSTs are benign occipital sleep or visual exploration patterns; Hyperventilation in normal young subjects typically causes generalized high-voltage slow waves; Marked asymmetry or absent hyperventilation response is abnormal