Activation of the orbitofrontal cortex by both meditation and exercise: A near-infrared spectroscopy study

Figures

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  Fig 1. Experimental protocol. First, the CES-D was administered to the participants, and then 3 tasks: meditation, exercise, and a control task, were performed by the participants in a randomly selected order. After each task, a 2-back test was administered while the NIRS measurement was simultaneously performed.

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  Fig 2. NIRS measurement. A. A typical picture of a participant equipped with NIRS optodes. B. The NIRS comprised 8 elements for the NIR light emitter (red) and 7 elements for the detector (blue). The numbers indicate the channels (green) recorded. The NIRS channels were placed above the dorsolateral prefrontal cortex (DLPFC) and the orbitofrontal cortex (OFC). C. The channels between the optodes measured on the skull were assigned to the brain regions using the virtual registration method.

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  Fig 3. Scores (correct answer rate) in the 2-back tests. All participants performed the 2-back tests after meditation (red), exercise (blue), and control (yellow) tasks. The scores are shown as mean ± SEM. There is no significant difference.

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  Fig 4. Representative NIRS signals and their FFT data. A. At CH14 in a participant, the oxyhemoglobin NIRS signals (red lines) were obtained during the 2-back tests after meditation, exercise, and a control task. These figures show only typical signal changes as examples. B. FFT values calculated from the data of a left-handed participant. C. FFT values calculated from the data of a right-handed participant. Red line indicates the meditation data; blue line indicates those of exercise; and yellow line indicates those of control.

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  Fig 5. Correlation coefficients of the FFT-analyzed NIRS frequency at the DLPFC and the OFC for the meditation-control pair (red), the exercise-control pair (green), and the meditation-exercise pair (blue). A Mann-Whitney U-test was performed after an F test for equal variance. *p < 0.05. The diagonal lines show the changes in mean values obtained from the 2 left-handed participants.

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  Fig 6. Coefficient correlations of FFT-analyzed NIRS frequencies at each channel among the meditation-control pair (red), the exercise-control pair (green), and the meditation-exercise pair (blue) analyses. The CH14 and CH18 showed significant differences only in the meditation-exercise pair (blue). One-way analysis of variance (ANOVA) followed by a post-hoc Tukey test was performed. For CH14, F(2,48) = 3.407, *p < 0.05; for CH18, F(2,48) = 3.207, *p < 0.05.

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  Fig 7. Signal source analysis for CH14 and CH18. A. Representative data of spread of signals originating in CH14 and CH18 are shown. Numbers indicate the time at the maximum peak value of the correlation coefficients after the peak emergence of CH14 or CH18. B. Ratios of CH14 or CH18 recognized as the signal source are shown for the 17 participants. Error bars indicate 95% CI (e.g., 10.4% for both CH14 and CH18), and if the error bars did not overlap, we determined that there was a significant difference between the tasks. * indicates a significant difference.