Proposed term	Assessment method	Morphology / physiology	Frequency	Unit
Slow oscillation (SO)	Intracellular, extracellular unit firing, cortical LFP and cortical EEG	De- and hyperpolarized membrane potential states, cycles of spiking activity, positive and negative field deflections. Each state lasts more than 100 ms (typically above 200 ms).	< 1 Hz	Hz
Slow wave (SW)	Intracellular, extracellular unit firing, cortical LFP and scalp EEG	Same as above, but individual wave, number / density / morphology thereof		Single wave
Slow wave activity (SWA)	Intracranial EEG, scalp EEG	Integrated signal, representing multiple overlapping SW	0.5–4.5 Hz	μV2