Article Figures & Data
Figures
- Figure 1.
Simple Discrimination task. A, Four example Simple Discrimination trials. Bottom, Correct and incorrect choices are indicated by an orange dot and red X, respectively. The first two examples show the last two trials of Problem (Prob) 1. The next two examples show the first two trials of Problem 2. B, Errors to criterion by age group. Aged marmosets made more errors to criterion than young marmosets when performance was averaged across all six Simple Discrimination problems. Bars show mean ± SEM; *p < 0.05. C, Correlations between errors to criterion and problem by age group. Young marmosets (open circles) performed equally well on all problems, whereas aged marmosets (black circles) improved their performance over the six Simple Discrimination problems. D, Correlations between errors to criterion and age for each of the Simple Discrimination problems. Strong and significant positive correlations between age and errors to criterion were observed for Problems 1 and 2 but not for Problems 3–6.
- Figure 2.
Age-related impaired Simple Discrimination performance is accounted for by increased duration of the Latent Phase. A, Representative marmoset learning curve showing performance on one Simple Discrimination problem. Open circle on the curve marks the point at which performance was significantly above chance (50%) and remained so for the duration of the problem. B–C, Correlations between age and number of trials in the Latent Phase (B) and Criterion Phase. C, The duration of the Latent Phase accounts for the age-related impairment on Problems 1 and 2 *p < 0.05.
- Figure 3.
Serial Reversal task. A, Example of four Serial Reversal task trials. Bottom, Correct and incorrect choices are indicated by an orange dot and red X, respectively. The first two examples show the last two trials of the Simple Discrimination problem that precedes the first reversal. The next two examples show the first two trials of Reversal 1. B, Errors to criterion by age group. Aged marmosets made more errors to criterion than young marmosets when performance was averaged across all five reversals. Bars show mean ± SEM; *p < 0.05. C, Correlations between errors to criterion and reversal by age group. Young marmosets (open circles) performed equally well on all problems, whereas aged marmoset (black circles) performance worsened over the five reversals. D, Correlations between errors to criterion and age for the Simple Discrimination problem and each of the reversals. Strong positive correlations between advancing age and poorer performance existed for all the reversals.
- Figure 4.
Age-related impaired Serial Reversal performance is accounted for by increased duration of the Dynamic Phase. A, Representative marmoset learning curve showing performance on one reversal. The first trial on the x-axis corresponds to the first trial after the reward contingencies were switched. Bottom left, The lower circle on the curve marks the point at which performance was statistically above 10% accuracy and remained so for the duration of the reversal. Trials before this point are included in the Transition Phase. Top right, The open circle indicates the point at which performance exceeded chance levels (50%) and remained above chance for the remainder of the reversal. Trials above this point are included in the Criterion Phase. Trials between the end of the Transition Phase and beginning of the Criterion Phase are included in the Dynamic Phase. B–D, Correlations between age and number of trials in the Transition Phase (B), Dynamic Phase (C), and Criterion Phase (D). The duration of the Dynamic Phase accounts for the overall age-related impairment in cognitive flexibility (B–D); *p < 0.05.
Tables
Problem Latent Phase Criterion Phase Problem 1 rs(9) = 0.68, p = 0.02 rs(9) = −0.21, p = 0.54 Problem 2 rs(9) = 0.61, p = 0.05 rs(9) = −0.16, p = 0.63 Problem 3 rs(9) = 0.17, p = 0.61 rs(9) = 0.03, p = 0.94 Problem 4 rs(9) = 0.47, p = 0.15 rs(9) = 0.30, p = 0.38 Problem 5 rs(9) = 0.38, p = 0.25 rs(9) = 0.15, p = 0.66 Problem 6 rs(9) = 0.45, p = 0.16 rs(9) = 0.19, p = 0.58 The length of the Latent Phase changed as a function of age for the first two Simple Discrimination problems but not for any of the later four. The length of the Criterion Phase did not change as a function of age for any of the Simple Discrimination problems.
Reversal Transition Phase Dynamic Phase Criterion Phase Reversal 1 rs(5) = 0.67, p = 0.12 rs(5) = 0.86, p = 0.02 rs(5) = −0.29, p = 0.56 Reversal 2 rs(5) = 0.13, p = 0.79 rs(5) = 0.89, p = 0.01 rs(5) = 0.07, p = 0.91 Reversal 3 rs(5) = 0.68, p = 0.11 rs(5) = 0.68, p = 0.11 rs(5) = 0.50, p = 0.25 Reversal 4 rs(5) = 0.71, p = 0.09 rs(5) = 0.89, p = 0.01 rs(5) = −0.25, p = 0.59 Reversal 5 rs(5) = 0.02, p = 0.67 rs(5) = 0.79, p = 0.04 rs(5) = 0.21, p = 0.66 The length of the Dynamic Phase significantly increased as a function of age, whereas the lengths of the Transition and Criterion Phases did not vary significantly as a function of age.
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