Enhancing Attention by Synchronizing Respiration and Fingertip Pressure: A Pilot Study Using Functional Near-Infrared Spectroscopy

Figures

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  FIGURE 1. Experimental procedures. (A) Experiment 1. Twelve participants carried out HAM and BCM on two consecutive days. (B) Experiment 2. Twenty participants were allocated randomly to the experimental or control group who conducted 5-day training of HAM or BCM, respectively. Both groups conducted a battery of tests before and after the training. For the experimental group, fNIRS signals during ANT and SART before and after the training, and during the last training session were recorded. HAM, haptics-assisted meditation; BCM, breath-counting meditation; fNIRS, functional near-infrared spectroscopy; ANT, attention network task; SART, sustained attention to response task.

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  FIGURE 2. Haptics-assisted meditation. Participants conducted the breath-counting task in block 1. In block 2, “positive mapping” mode, participants were required to increase the fingertip pressure when inhaling and decrease when exhaling. Block 3, “negative mapping” mode, is similar to block 2 with the difference that participants decreased the fingertip pressure when inhaling and increased when exhaling. In block 4, “hybrid mapping” mode, participants performed the positive mapping or negative mapping mode every 10 respiratory cycles.

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  FIGURE 3. Gabor patch discrimination task. (A) Procedure of one trial. (B) Eighteen pictures that could be presented in the task.

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  FIGURE 4. Example data of respiration signals and forces from bilateral index fingers in (A) positive mapping and (B) negative mapping.

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  FIGURE 5. fNIRS measurement. (A) Photograph of fNIRS measurement on a participant. (B) Schematic of imaging pad. Twenty-two emitters (red dots) and 24 detectors (blue dots) were symmetrically placed on the bilateral hemispheres and constituted 64 measurement channels (gray lines), allowing for the prefrontal and sensorimotor cortices to be measured. The emitter R was placed in Cz of the international 10–20 system. (C) Anatomical position of each measurement channel.

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  FIGURE 6. (A) Number of mind-wandering self-reports during HAM (red bars) and BCM (black bars). (B) Comparison of performance changes between the HAM (red bars) and BCM groups (black bars). The vertical axis indicates the task performance. The horizontal axis indicates the percentage of performance change after training [i.e., (Post – Pre)/Pre × 100%]. The positive values marked in gray represent that increased performance is expected for the task; the negative values marked in gray represent that decreased performance is expected. ∗ and ∗∗ denote significant changes of performance within the HAM or BCM group; ∗, p < 0.05; ∗∗, p < 0.01. †denotes a significant difference in the performance changes between the HAM and BCM groups (p < 0.05). HAM, haptics-assisted meditation; BCM, breath-counting meditation.

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  FIGURE 7. Behavioral performance during HAM training. (A) Mean ΔTS values of all sessions for block 2 (positive mapping), block 3 (negative mapping), and block 4 (hybrid mapping). The green patterns represent ΔTS computed from the right, and the yellow patterns represent ΔTS from the left. (B) Mean attentional scores for the whole session reported by all participants. (C) Mean attentional scores for each block. HAM, haptics-assisted meditation.

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  FIGURE 8. Changes in the concentration of oxy-Hb and deoxy-Hb after training (post minus pre). t-value maps obtained by paired t-tests on (A) oxy-Hb and (B) deoxy-Hb. Each number in these maps denotes the numbering of optical channels. The numbers marked in bold denote that the changes in these channels were significant statistically. The positive t-values in the color bar represent higher concentration in posttests than in pretests, and the negative values represent lower concentration than in the pretests.

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  FIGURE 9. Changes in FC after training (post minus pre). (A) FC matrices across all channels. Each number (1–64) in the x- or y-axis denotes the numbering of optical channels. The color bar indicates the value of the Pearson correlation coefficient. (B) FC that increased or decreased significantly (p < 0.05) after the training, marked with red or blue lines, respectively. FC, functional connectivity.

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  FIGURE 10. t-value maps obtained by paired t-tests on (A) oxy-Hb and (B) deoxy-Hb for each block. The numbers marked in bold denote that these channels showed significant changes than during resting state.

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  FIGURE 11. FC for four HAM blocks. (A) FC matrices across all channels. (B) FC that increased or decreased significantly (p < 0.05) marked by red or blue lines, respectively. FC, functional connectivity; HAM, haptics-assisted meditation.