I have one question: Why is a baseline theta needed in order to get the model (any OI model) to work?
I understand, that we have a bunch of oscillators. When the animal moves in the preferred direction of the oscillator, then this oscillator speeds up slightly. For whatever reason, the oscillators never slow down. So if we think of a 1D case with 2 oscillators, then movement in one direction, makes one of the oscillators go faster. Movement in the other direction lets the other oscillator go faster. Interference occurs at the readout node (grid-cell).
But I do not understand, why a baseline frequency is needed. The model seems to work without it. Or is a baseline frequency just helpful, because it replaces the need for an extra oscillator, but the model works as well without the baseline, and another oscillator.