Adaptation and sensorimotor processing during increased gravity gradients

Gravity, a constant physical factor that has shaped evolution and maintains the health of physical bodies on Earth. The physiological deconditioning of the human body exposed to microgravity and simulated microgravity environments (bed rest and dry immersion) is now well known, and artificial gravity created by spinning on a short-arm human centrifuge has been recognized as a valuable countermeasure. Centrifugation as a means of mitigating the disadvantages caused by bed rest has been shown to improve orthostatic tolerance time, reduce plasma volume reduction, and increase exercise capacity, however, the processes of adaptation and altered sensorimotor processing are not well understood. The role of the central nervous system in an altered gravity environment is now frequently discussed as the driving force of these adaptive processes, as its plastic mechanisms affect spatial orientation, sensorimotor control, and cardiovascular dynamics acutely and even the cardiovascular and musculoskeletal systems as a result of a prolonged reduced gravity period. Through a systematic review of the literature and two separate experiments, we aim to establish the necessary foundation and make an additional contribution to this field. We plan to recruit and test healthy women and men (18-45 years) while they are following a strict centrifugation protocol. Experienced research teams will collaborate on this interdisciplinary project, which will require knowledge of biomedical engineering, motor control and learning, neuroscience, and physiology to provide a comprehensive picture. Using state-of-the-art equipment, we will closely monitor various subsystems of the human body, including neurovascular and neurophysiological responses. In a 3-year project, we will pursue the activities of five work packages that are closely linked to achieve our final goals: Preparation and publication of i) Systematic review I - Adaptation processes to elevated gravity gradients; ii) Systematic review II - Physiological changes affecting sensorimotor processing and performance during elevated gravity gradients; iii) Scientific publication providing the most effective adaptation process and recommendations for optimal use of the short arm human centrifuge; iv) Scientific publication providing results on altered sensorimotor processing and overall reduced performance at elevated G levels. A deeper understanding of these adaptation mechanisms would not only allow us to develop an effective and user-friendly protocol for centrifuge prescription, but would also have immediate implications for aviators piloting and landing aircraft and spacecraft.