Figure 1.
Cognitive bias test apparatus.
(A) Schematic diagram of the apparatus used in experiment I and II displaying the start box, the starting corridor, the central platform, the positive and negative reference arm, the three probe arms, and the sliding doors. In experiment I both reference arms had either a positive or a negative outcome and only the central probe arm was used for the probe trial. (B) Apparatus used in experiment III with the start cylinder positioned in the starting corridor, the central platform, the positive and negative reference arm, and the ambiguous probe arm. Unused arms were closed by reversing them so that their closed end functioned as barrier. Please note: The position of the positive and negative reference location in experiment II and III was counterbalanced between individuals.
Figure 2.
(A) Latency to reach the arm, (B) latency to reach the hole, and (C) percentage of time spent at the hole for mice being confronted with solely positive (optimistically-trained mice, n = 7) or solely negative (pessimistically-trained mice, n = 7) experience across the three days of training. Data are averaged per treatment group and day and are presented as means ±SEM. Day 1: 5 trials, day 2: 6 trials, day 3: 2 trials. See results section for details of statistical analysis.
Figure 3.
(A) Latency to reach the arm, (B) latency to reach the hole, and (C) time spent at the hole in the central probe arm for mice that have been confronted with solely positive (optimistically-trained mice, n = 7) or solely negative (pessimistically-trained mice, n = 7) experiences during training. Data are presented as means ±SEM. Statistics: ANOVA, main effect of treatment: *p≤0.05, tp≤0.1.
Figure 4.
(A) Latency to reach the arm, (B) latency to reach the hole, and (C) percentage of time spent at the hole in positive and negative trials across the four days of training for mice being later confronted with the near-negative (NN, n = 7), central (CE, n = 10), or near-positive (NP, n = 11) probe arm. Data are averaged per trial outcome and day and are presented as means ±SEM. Day 1: 5 positive trials, day 2+3: 3 positive and 3 negative trials, day 4: 2 positive and 2 negative trials. Statistics: day 1: ANOVA; day 2–4: Repeated Measures ANOVA for each day, main effect of trial outcome: ***p≤0.001, tp≤0.1, effect of group-by-trial outcome interaction: #p≤0.1.
Figure 5.
Experiment II: Cognitive bias test.
(A) Latency to reach the arm, (B) latency to reach the hole, and (C) time spent at the hole for mice being confronted with either the near-negative (NN, n = 7), central (CE, n = 10), or near-positive (NP, n = 11) probe arm. Data are presented as means ±SEM. Statistics: ANOVA, post hoc testing: Games-Howell test, **p≤0.01, *p≤0.05, tp≤0.1.
Figure 6.
Latency to reach the hole in positive and negative trials across the five days of training days for 5-HTT +/+ (n = 5), 5-HTT +/− (n = 9), and 5-HTT −/− mice (n = 6). Data are averaged per trial outcome and day and are presented as means ±SEM. Day 1: 5 positive trials, day 2+3+4: 3 positive and 3 negative trials, day 5: 1 positive and 1 negative trial. Statistics: day 1: ANOVA; day 2–4: Repeated measures ANOVA for each day, main effect of trial outcome ***p≤0.001; day 5: Wilcoxon signed-rank tests (two-tailed), *p≤0.05 within each genotype.
Figure 7.
Experiment III: Cognitive bias test.
Experiment III: Cognitive bias test. Latency to reach the hole in the central probe arm for 5−HTT +/+ (n = 5), 5−HTT +/− (n = 9), and 5−HTT −/− mice (n = 6). Data are presented as means ± SEM.