2018 Volume 17 Pages 61-70
The aim of this study was to clarify the effect of sensory stimulation of the feet by different temperatures on cerebral blood flow in the prefrontal cortex. The feet of 25 healthy adults were stimulated for 180 sec in foot baths set at temperatures of 40℃, 16℃ and 30℃. Changes in cerebral blood flow in the left and right prefrontal cortex were measured using near-infrared spectroscopy, and the feeling experienced at each temperature and the pleasantness of the temperature were subjectively evaluated. In intragroup comparisons, cerebral blood flow in the left prefrontal cortex increased 120 sec from the start of immersing the feet in the 40℃ water bath as compared with baseline levels (P<0.05). Intergroup comparisons also showed that cerebral blood flow in the left prefrontal cortex was greater at 60 sec and 120 sec from the start of immersion of the feet in the 40℃ water bath than in the 16℃ water bath (P<0.05). However, no change was seen in cerebral blood flow in the right prefrontal cortex. In the subjective evaluation, 40℃ was considered a “warm” sensory stimulus with a “pleasant feeling,” while 16℃ was considered a “cold” sensory stimulus with an “unpleasant feeling.” These results demonstrate that the “pleasant feeling” resulting from “warm” sensory stimulation of the feet causes cerebral blood flow in the left prefrontal cortex to increase more than the “unpleasant feeling” resulting from “cold” sensory stimulation. These results also show that sensory stimulation of the feet do not produce any changes in cerebral blood flow to the right prefrontal cortex.