Fig. 4

Entrainment of low/high theta rhythm according to different locomotive states. (A) Example frame of a group session recording and the position trace of 8 mice and a robot. Colored squares indicate past positions (from −1 s to 0 s). Positions further in the past are represented in dim colors, while recent positions are depicted vividly. Note that even in the same threat situation, there were mice actively fleeing (e.g., M3) while others remained motionless in corners (e.g., M8). (B) Example of LFP traces in the time domain (left) and frequency domain (right) recorded from the mPFC. Note that, within the recent 1-second relative to the frame, high theta (~10 Hz) activity is prominent in M3 (flight-like locomotion), whereas low theta (~5 Hz) activity is prominent in M8 (freezing-like immobility). (C) Example LFP amplitude spectra as a function of mouse movement speed (Greenish color: slow movement; Reddish color: fast movement) from a solitary recording. (D) Similar to (C), but in a group recording. (E) Theta ratio (i.e., amplitude of 8–12 Hz divided by 3–8 Hz amplitude) derived from (C) and (D). (F) Grand-averaged theta ratio derived from the entire dataset. Error bars indicate ± 1 the standard deviation of the mean.