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Effect of Gravity on the Caloric Stimulation of the Inner Ear
Author(s) -
KASSEMI MOHAMMAD,
DESERRANNO DIMITRI,
OAS JOHN G.
Publication year - 2004
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1324.030
Subject(s) - endolymph , buoyancy , convection , caloric theory , expansive , weightlessness , anatomy , geology , stimulation , mechanics , physics , inner ear , biology , neuroscience , astronomy , thermodynamics , compressive strength
A bstract : Robert Bárány won the 1914 Nobel Prize in medicine for his convection hypothesis for caloric stimulation. Microgravity caloric tests aboard the 1983 SpaceLab 1 mission produced nystagmus results that contradicted the basic premise of Bárány's convection theory. In this paper, we present a fluid structural analysis of the caloric stimulation of the lateral semicircular canal. Direct numerical simulations indicate that on earth, natural convection is the dominant mechanism for endolymphatic flow. However, in the microgravity environment of orbiting spacecraft, where buoyancy effects are mitigated, an expansive convection becomes the sole mechanism for producing endolymph motion and cupular displacement. Transient 1 g and microgravity case studies are presented to delineate the different dynamic behaviors of the 1 g and microgravity endolymphatic flows. The associated fluid‐structural interactions are also analyzed based on the time evolution of cupular displacements.