Physiological effects of forest-related visual, olfactory, and combined stimuli on humans: An additive combined effect

《Physiological effects of forest-related visual, olfactory, and combined stimuli on humans: An additive combined effect》

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作者: Chorong Song;Harumi Ikei;Yoshifumi Miyazaki

来源: URBAN FORESTRY & URBAN GREENING,Vol.44,Issue1,Article 126437

语言: 英文

关键字: Oxy-Hboxyhemoglobin;HRVheart rate variability;HFhigh frequency;LFlow frequency;TRSnear-infrared time-resolved spectroscopy;Forest therapy;Heart rate variability;Near-infrared spectroscopy;Physiological relaxation;Preventive medicine;Shinrin-yoku

作者单位: Center for Environment, Health and Field Sciences, Chiba University, 6-2-1 Kashiwa-no-ha, Kashiwa, Chiba, 277-0882, Japan;Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan;Center for Environment, Health and Field Sciences, Chiba University, 6-2-1 Kashiwa-no-ha, Kashiwa, Chiba, 277-0882, Japan;Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan

摘要: The aim of this study was to investigate the physiological effects on brain activity and autonomic nervous activity of forest-related visual, olfactory, and combined visual and olfactory stimuli. Twenty-one female Japanese university students (age, 21.1 ± 1.0 years) participated. In a soundproofed chamber with an artificial climate, each participant was presented for 90 s with the following conditions: an image of a forest landscape of Hinoki cypress trees with no odor (visual stimulus), a gray image with Hinoki cypress leaf essential oil (olfactory stimulus), an image of a forest landscape of Hinoki cypress trees with Hinoki cypress leaf essential oil (combined stimulus), and a gray image with no odor (control). As an indicator of brain activity, oxyhemoglobin concentrations were measured in the left and right prefrontal cortices using near-infrared time-resolved spectroscopy. Heart rate variability and heart rate were used as indicators of autonomic nervous activity. The high-frequency component of heart rate variability, which reflects parasympathetic nervous activity, and the low-frequency/high-frequency ratio, which reflects sympathetic nervous activity, were evaluated. The following results were obtained in comparison with the control conditions: (1) the combined stimuli resulted in significantly decreased oxyhemoglobin concentrations in the left and right prefrontal cortices; (2) the olfactory stimulus resulted in significantly decreased oxyhemoglobin concentration in the right prefrontal cortex; and (3) the visual stimulus resulted in significantly decreased sympathetic nervous activity related to arousal or situations of stress. Results of a questionnaire indicated that these forest-related stimuli significantly increased the participants’ feelings of “comfortable” and “relaxed,” with the visual and combined stimuli significantly increasing feelings related to the terms “natural” and “realistic.” In conclusion, forest-related visual, olfactory, and combined visual and olfactory stimuli induced physiological and psychological relaxation effects, and the combined visual and olfactory stimuli exhibited an additive effect.