Anterior and posterior human hippocampus display different theta rates and functions (spatial vs non-spatial processing): www.nature.com/articles/s41...

Functionally distinct high and low theta oscillations in the human hippocampus - Nature Communicatio...

We show that the human hippocampus exhibits two distinct theta oscillations during spatial navigation with the faster oscillation in posterior regions showing movement modulation. This result suggests...

Oh yeah, I also just stumbled about this one. I am actually surprised that there doesn't seem to be review on this even though this has been discussed since the very first imaging studies and probably before in lesion studies.