Figure 1.
The grey mouse lemur (Microcebus murinus) represents the smallest primate aging model.
Photograph taken by Dr. Christian Schopf.
Table 1.
Performance of the mouse lemurs during the acquisition of the visual discrimination (PD) and the reversal learning (PDR).
Figure 2.
Test chamber (PD+ PDR task, top view).
TS = touchscreen device; RW1, RW2 = response windows; RT = reward tray.
Figure 3.
Representative learning curves of young and old mouse lemurs in the visual pair-wise discrimination task (PD) and its reversal (PDR).
A Learning curves of a good (POP, UND) and a bad (PEA, WIL) PD learner from each age category (red = young subjects; blue = old subjects). B Learning curves of a good (PEG, URS) and a bad (PAU, WIL) PDR learner from each age category (red = young subjects; blue = old subjects).
Figure 4.
Performance of young and aged mouse lemurs in the visual discrimination task (PD).
** Indicates a significant difference with p<0.01. Nyoung = 15, Naged = 9. The box represents the lower quartile, median, and upper quartile, the whiskers represent the minimum and maximum values.
Figure 5.
Performance of males and females in the visual discrimination task (PD).
A Results for the young mouse lemurs and B results for the aged mouse lemurs. + Indicates a trend with 0.05<p<0.1. Nyoung males = 7, Nyoung females = 8, Naged males = 3, Naged females = 6. The box represents the lower quartile, median, and upper quartile, the whiskers represent the minimum and maximum values.
Figure 6.
Performance of young and aged mouse lemurs in the reversal learning task (PDR).
* Indicates a significant difference with p<0.05. Nyoung = 20, Naged = 10. The box represents the lower quartile, median, and upper quartile, the whiskers represent the minimum and maximum values.
Figure 7.
Performance of males and females in the reversal learning task (PDR).
A Results for the young mouse lemurs and B results for the aged mouse lemurs. + Indicates a trend with 0.05<p<0.1. Nyoung males = 10, Nyoung females = 10, Naged males = 4, Naged females = 6. The box represents the lower quartile, median, and upper quartile, the whiskers represent the minimum and maximum values.
Figure 8.
Perseverance of young and aged mouse lemurs in the reversal learning task (PDR).
A Number of trials needed to reach the 50% criterion in the PDR. B Number of perseverative errors made until reaching the 50% criterion in the PDR. * Indicates a significant difference with p<0.05. Nyoung = 20, Naged = 10. The box represents the lower quartile, median, and upper quartile, the whiskers represent the minimum and maximum values.
Figure 9.
Correlation between individual PD and PDR performances.
Number of trials needed to reach criterion in the reversal learning task (PDR) plotted against the number of trials needed to reach criterion in the visual discrimination task (PD) (Ntotal = 24). The solid black line represents the regression line, the dashed red lines represent the 95% confidence interval as estimated from the linear regression model. The individual performances in PD and PDR are highly significantly correlated (Spearman's rank correlation, r = 0.72, p = 0.00007).