Heart Rate and Heart Rate Variability Assessment Identifies Individual Differences in Fear Response Magnitudes to Earthquake, Free Fall, and Air Puff in Mice
(A) Instant HR responses of an individual mouse during three free fall stimuli, trial #1, trial #4 and trial #7. The red vertical dashed lines indicate the onset of the free fall stimuli (13 cm high). (B) Poincaré plots of the same mouse’s R-R intervals of 30-s pre-stimulus (grey line) and 30-s post-stimulus (red line) period in trial #1, trial #4 and trial #7. Immediate decrease in dynamic patterns in HRV after stimulus onset was noted at trial #1, but more diffused distribution in the 30-s post-stimulus period in trial #4 and trial #7. (C) The average HR response to free fall (1st trial). (D) The average CV of R-R intervals upon 1st trial of free fall. (E) The average RMSSD of R-R intervals upon 1st trial of free fall. The average curves of 30-s pre-stimulus period were plotted as grey lines, whereas the average curves of 90-s post-stimulus period were plotted as red lines. The shadows around the average curves indicate error bars (SEM); n = 7.