Open Access
Long-duration head down bed rest as an analog of microgravity: Effects on the static perception of upright
Author(s) -
Laurence R. Harris,
Michael Jenkin,
Rainer Herpers
Publication year - 2022
Publication title -
journal of vestibular research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.118
H-Index - 53
eISSN - 1878-6464
pISSN - 0957-4271
DOI - 10.3233/ves-210016
Subject(s) - bed rest , rest (music) , perception , orientation (vector space) , psychology , audiology , simulation , mathematics , computer science , medicine , neuroscience , surgery , geometry
BACKGROUND: Humans demonstrate many physiological changes in microgravity for which long-duration head down bed rest (HDBR) is a reliable analog. However, information on how HDBR affects sensory processing is lacking. OBJECTIVE: We previously showed [25] that microgravity alters the weighting applied to visual cues in determining the perceptual upright (PU), an effect that lasts long after return. Does long-duration HDBR have comparable effects? METHODS: We assessed static spatial orientation using the luminous line test (subjective visual vertical, SVV) and the oriented character recognition test (PU) before, during and after 21 days of 6° HDBR in 10 participants. Methods were essentially identical as previously used in orbit [25]. RESULTS: Overall, HDBR had no effect on the reliance on visual relative to body cues in determining the PU. However, when considering the three critical time points (pre-bed rest, end of bed rest, and 14 days post-bed rest) there was a significant decrease in reliance on visual relative to body cues, as found in microgravity. The ratio had an average time constant of 7.28 days and returned to pre-bed-rest levels within 14 days. The SVV was unaffected. CONCLUSIONS: We conclude that bed rest can be a useful analog for the study of the perception of static self-orientation during long-term exposure to microgravity. More detailed work on the precise time course of our effects is needed in both bed rest and microgravity conditions.