Figure 3
From: Novel insights into the behavioral analysis of mice subjected to the forced-swim test
The distribution of the durations of bouts of immobility (tim). (a) Examples of one mouse with longer tims (filled circles) and the other with shorter tims (open circles) during the entire swim session of 6 min. The tims are plotted against the time at which the immobility occurred. The two dashed lines show the traditional arbitrary thresholds of 1 s and 2 s for screening the first bout of immobility. (b) Cumulative probability of the tims of the two mice shown in a. (c) Cumulative probability of the tfirst_ims of 57 mice used in the 6-min FST. The open and filled triangles show the traditional arbitrary thresholds of 1 s and 2 s, respectively, for the calculation of tlat. (d) The histogram of the log values of all the tfirst_ims shown in c. The histogram follows a log-normal distribution. (e) Immobility durations of a mouse (tim) plotted against the time at which the immobility occurred during the 6-min FST. The two dashed lines show the traditional arbitrary thresholds of 1 s and 2 s for screening the first bout of immobility. (f) Cumulative probability of the tims shown in a. The open circles are fitted with either two normal distributions (black line) or one normal distribution (green line). The residual sum of squares (RSS) when fitting with one or two distributions are RSS1=0.201 and RSS2=0.007, respectively. The F-value calculated with RSS1 and RSS2 is 223.689 (P=1.897e−19). When fitting with two normal distributions, the blue dashed line is the mean of the first distribution, the red dashed line is the mean of the second distribution and the open triangle shows the new threshold (tc) for screening the first critical immobility calculated as the weighted mean of the two distributions. FST, forced-swim test; tc, critical threshold.
