Review on the impact of spaceflight stressors on the vestibular system: beyond microgravity to space radiation

Understanding the effects of microgravity on the vestibular system has been a primary focus of space research, driven by the need to counteract the often-debilitating impacts of altered gravity environments and maintain operational performance in space. Research using both space-based and ground-based models has identified structural and functional changes in the vestibular system, highlighting its significant capacity for sensorimotor adaptation. As human space exploration progresses towards missions beyond low Earth orbit for extended periods, additional stressors, such as space radiation, may impact the vestibular system. Early studies on space radiation using animal models and insights from radiotherapy have shown that the vestibular system is more vulnerable to radiation than previously understood. This paper provides a brief review of (1) dysfunctions in spatial orientation, gaze stabilization, posture, and locomotion observed in astronauts; (2) ground-based experiments on animals that likely explain these vestibular and sensorimotor dysfunctions; and (3) studies examining the effects of radiation on the vestibular system and its implications for vestibular function in space.