Discussion of imalsogreg's comment: Rats were made to 'walk' left while moving right (by putting them on a small treadmill mounted on a model train), while recording place cells. Does theta phase continue to correlate with absolute position within the place field? No. Phase precession is 'reversed'. Likewise, theta sequences start from where the rat came from, and extend to where he is going, regardless of the direction he faces while running. Interestingly contradicts most network models of theta sequences.