Immersion in nature through virtual reality attenuates the development and spread of mechanical secondary hyperalgesia: a role for insulo-thalamic effective connectivity.

Nature-based social prescribing has been shown to improve physical and mental health and is increasingly used to manage chronic pain. However, the mechanisms of nature-based analgesia remain unclear. In this study, we used immersive virtual reality (VR) alongside pain psychophysics, functional magnetic resonance imaging, and psychometric assessments to assess the brain-based mechanisms of nature-based pain relief. Specifically, we experimentally induced sensitisation within central nociceptive pathways using the high frequency stimulation model of pain in 30 healthy participants and tracked the development of secondary mechanical hyperalgesia across 3 conditions: immersive VR nature, nonimmersive 2D nature video, and no intervention. Immersive nature VR significantly reduced the development and spread of mechanical secondary hyperalgesia, with sustained analgesic effects correlating with perceived presence. Bayesian modelling of neuroimaging end points collected separately revealed that nature VR-induced analgesic effects correlated with insulo-thalamic effective connectivity. We propose that the analgesic effects of nature are likely mediated through top-down endogenous analgesic systems which could be working to reduce the development and spread of heterotopic plasticity in the spinal cord.