Department of Psychiatry, Brighton and Sussex Medical School, Brighton, UK.
Sackler Centre for Consciousness Science, University of Sussex, Brighton, UK.
Sci Rep. 2017 Mar 27;7:45273. doi: 10.1038/srep45273.
Naturalistic environments have been demonstrated to promote relaxation and wellbeing. We assess opposing theoretical accounts for these effects through investigation of autonomic arousal and alterations of activation and functional connectivity within the default mode network (DMN) of the brain while participants listened to sounds from artificial and natural environments. We found no evidence for increased DMN activity in the naturalistic compared to artificial or control condition, however, seed based functional connectivity showed a shift from anterior to posterior midline functional coupling in the naturalistic condition. These changes were accompanied by an increase in peak high frequency heart rate variability, indicating an increase in parasympathetic activity in the naturalistic condition in line with the Stress Recovery Theory of nature exposure. Changes in heart rate and the peak high frequency were correlated with baseline functional connectivity within the DMN and baseline parasympathetic tone respectively, highlighting the importance of individual neural and autonomic differences in the response to nature exposure. Our findings may help explain reported health benefits of exposure to natural environments, through identification of alterations to autonomic activity and functional coupling within the DMN when listening to naturalistic sounds.
自然环境已被证明能促进放松和幸福感。我们通过考察自主唤醒以及大脑默认模式网络（DMN）的激活和功能连接的变化，评估了这些效应的对立理论解释，参与者在听人工和自然环境的声音时进行了这些评估。我们没有发现自然环境比人工或对照条件下 DMN 活动增加的证据，然而，基于种子的功能连接显示出自然条件下从前中线到后中线功能耦合的转变。这些变化伴随着高频心率变异性峰值的增加，表明自然条件下副交感活动的增加符合自然暴露的应激恢复理论。心率和高频峰值的变化与 DMN 内的基线功能连接以及基线副交感神经张力分别相关，这突出了个体神经和自主差异对自然暴露反应的重要性。我们的发现可能有助于通过在聆听自然声音时识别自主活动和 DMN 内功能连接的变化，解释报告的暴露于自然环境的健康益处。
