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Updated: Aug 15, 2026

Coherence between Brain Cortical Function and Neurocognitive Performance during Changed Gravity Conditions
Published on: May 23, 2011
Effect of gravity on the caloric stimulation of the inner ear
Mohammad Kassemi1, Dimitri Deserranno, John G Oas
1National Center for Microgravity Research, NASA Glenn Research Center, 21000 Brookpark Road, MS110-3, Cleveland, OH 44135, USA. mohammad.kassemi@grc.nasa.gov
Abstract:
Robert Barany 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 Barany'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.
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