Figure 8.

Spike precession with respect to LFP during place fields. (A) Magnification of first spike timing of all 19 cells (sample of cells with increasing mean) from a single run superimposed on extracellular theta within the third place field (B) For each spike in (A), phase with respect to LFP, with outer hull fit. (C) Location of spikes with respect to theta waveform. (See text, n = 30 fields). (D) Representative sample for clarity (25%) of outer hull fit of precession during third place fields; statistics were performed on all 30 runs (472 control cells, with increasing mean). Black dashed line, true center of place field; red dashed line, mean timing of the troughs (maximal precession). Because spikes occur reliably at or near the peak of intracellular oscillation (i.e., there is no intracellular precession per se), and the intracellular oscillation frequency increases near the middle of the field, spike timing will appear to precess with respect to extracellularly measured theta LFP.