Fig 1.
Position of the hand on the participant’s back.
Fig 2.
Schematic representation of the probe settings and measurement regions for 52-channel near-infrared spectroscopy (NIRS).
Gray squares and numbers represent the measurement regions and channel numbers, respectively. Red and blue squares indicate near-infrared light emitter and detector positions, respectively.
Fig 3.
Changes in oxygenated hemoglobin (oxy-Hb) levels in response to touch.
Oxy-Hb levels at each channel before and after touching were compared using a paired t-test. We found a significant increase in oxy-Hb at channels 11, 14, 21, 22, 24, 32, 35, 45, 46, and 49. After employing false discovery rate (FDR) correction via the Benjamini–Hochberg method, the increase in oxy-Hb remained significant at channel 11. The numbers in the figures represent channel numbers.
Fig 4.
Changes in deoxy-Hb levels in response to touch.
Deoxy-Hb levels in each channel before and after touch stimuli were compared using a paired t-test. We found a significant decrease in deoxy-Hb at channels 10, 11, 14, 17, 21, 22, 24, 28, 29, 31, 32, 36, 38, 39, 42, 49, and 50. After using FDRHR correction, these decreases remained significant at channels 11 and 14. The numbers in the figures represent channel numbers.
Table 1.
Concentration changes in oxy and deoxy–Hb levels in response to touch.