Heart Rate Complexity and Autonomic Modulation Are Associated with Psychological Response Inhibition in Healthy Subjects

Figures

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  Figure 1. Experimental detail: Subject comfortably sits in front of the screen at 70 cm of distance from the monitor with the hand positioned near the spacebar of the computer keyboard. In the first task, the GO is represented by the white square, and the subject must hit the spacebar when it appears, and inhibit the response when the red square appears (the chess pattern with squares was the distractor). In the second task, the GO is represented by the appearance of a square with color equal to the previous square, while the NoGo is represented by a change in the appearance of the square color. The first square of the tasks appeared after 30 s of a black image. The stimulus duration was 500 ms and the interval of time between the stimuli was 1500 ms.

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  Figure 2. Multiscale Entropy and Complexity Index Scheme. (A) For each subject the tachogram was extracted in baseline, task 1, and task 2. N represents the length of each original detrended (trend line in red) time series (baseline N = 422 ± 100; task 1 N = 509 ± 83; task 2 N = 524 ± 102). (B) The sample entropy (SampEn) was calculated for the original and coarse-grained series A and B, setting the parameters m and r at 2 and 0.2, respectively. The complexity index (CI) was calculated as the sum of the SampEn of the scales 1 (original series), 2 (a), and 3 (b).

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  Figure 3. Mean errors during the tasks: number of errors during task 1 (green line) and task 2 (red line) along the time.

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  Figure 4. Boxplot of the HRV parameters: Boxplot of the natural logarithm of low-frequency power (LnLF) and high-frequency power (LnHF), and Complexity Index (CI) in resting-state (baseline) and during task 1 and task 2.

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  Figure 5. Correlations among HRV parameters and performance: Correlation among HRV parameters (SampEn (SE), Complexity Index (CI), HF power (LnHF), LF power (LnLF), LF/HF), performance levels (errors and Reaction Time) and age of the group. In red and black are the negative and positive correlations, respectively. (A) baseline; (B) task 1; (C) task 2.