Figure 5.

Velocity and acceleration modulation of theta power. A–C, 3D plots showing the interaction between velocity, acceleration, and normalized theta power for the stratum pyramidale (PYR; A), stratum radiatum (RAD; B), and the stratum lacunosum moleculare (LM; C) across all animals. A robust linear regression was fit to a plot of theta power versus velocity for LFP data from three hippocampal layers of each rat. The y-intercept given by the model was used to normalize theta power. D–F, 2D figures representing the top-down view of the 3D surface. Overlaid white arrows show the direction and magnitude of the local slope. G–I, Compass plots showing the average of the slope vectors (white arrows) from plots D–F. An average vector was generated for both the positive and negative acceleration halves of each plot. The average of each animal is shown in various colors, with the cohort mean shown in black. The angle of the cohort means are shown in bold outside of each compass plot. Note that vector angles close to 0° indicate that theta power was primarily modulated by velocity. As the vector angle increases toward 90°, acceleration makes more of a contribution.