A pilot study of spinal reflex modulation during immersive virtual reality exposure in humans.

BACKGROUND: The integration of virtual reality (VR) technologies into clinical rehabilitation and diagnostics is rapidly expanding, yet the neurophysiological mechanisms of their influence on spinal motor circuits remain poorly understood. This pilot study assessed the modulation of spinal reflex excitability during exposure to specific immersive audiovisual stimuli delivered via a virtual reality headset, compared to classical neuromodulation paradigm. MATERIALS AND METHODS: Twenty-one healthy volunteers completed a within-subject design. The H-reflex and M-response parameters of the soleus muscle were recorded at rest, during the Jendrassik maneuver, and in three VR scenarios ("roller coaster," "horror," and "relaxation"). Autonomic responses were assessed using RR interval duration and RMSSD. Statistical analysis was performed using nonparametric methods for repeated measures. RESULTS: H-reflex thresholds remained stable across all conditions (q > 0.1). H-reflex amplitude was significantly modulated: the Jendrassik maneuver caused bilateral facilitation of the reflex (q = 0.10 and q = 0.09 for the right and left legs, respectively), while VR stimuli designed to elicit emotional responses induced suppression (a significant reduction was observed in the non-dominant leg, q = 0.06, with a similar non-significant trend in the dominant leg). M-response parameters remained unchanged, indicating the stability of peripheral conduction. CONCLUSION: These preliminary results suggest that the specific immersive audiovisual stimuli tested in this study can selectively modulate spinal reflex excitability via central descending pathways rather than peripheral mechanisms. The results of this preliminary research provide a foundation for the design of future investigations.