The effect of long duration spaceflight on the human vestibular system and its consequences on the autonomic system

Datum: 22 juni 2016

Locatie: UAntwerpen, Campus Drie Eiken, Promotiezaal Q0.02 - Universiteitsplein 1 - 2610 Antwerpen-Wilrijk

Tijdstip: 16 uur

Promovendus: Emma Hallgren

Promotor: Floris Wuyts

Korte beschrijving: Doctoraatsverdediging Emma Hallgren - Faculteit Wetenschappen, Departement Fysica



Abstract

This thesis describes the effect of space travel on the human vestibular and cardiovascular system.

The vestibular system senses the body’s position and movements and provides this information to the brain. Part of the vestibular system, the otoliths, serves as the body’s gravity receptor. Symptoms related to failed balance control, such as dizziness, are commonly observed in astronauts returning from space. Here, we investigate the effect of microgravity on the otoliths, which play a crucial role in the deleterious effects of spaceflight on the human body. We examined 25 astronauts before and after a 6-month spaceflight. We found a statistically significant reduction of the otolith response after spaceflight.

Nine days after return to Earth, the response returned to the preflight level. We discovered that astronauts with a larger reduction in the otolith response also had more difficulties keeping a stable blood pressure upon standing. This corroborates, for the first time, the existence of a long-hypothesized link between the human vestibular and cardiovascular system. In addition, we found that the astronauts’ tilt perception was also affected by spaceflight. Understanding and ultimately mitigating such balance problems, faulty tilt estimates and dizziness is paramount to long-duration manned space exploration. One potential countermeasure is to expose the space crew to artificial gravity during flight, which may be subject of future research.