Question for the hippocampal ephys folks out there- I am trying to suss out some the intention behind colloquial words. Here is a power spectra density from Smith et al. (2000) collected during a rest period. WRT the question “How much power is in the 8 Hz band?”, a simple answer

is “more than in the 100-200Hz” band. However, theta is often described as 8Hz and rest is often described as a period when “theta is absent”. A dissociation is being applied between the power of the 8 Hz band (which is high) and what we mean by theta (which is absent?

“non-theta” state). What are the rules for this dissociation? Can we safely say “theta is absent”?