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Investigating High-Frequency Vestibular Function: A Potential Flight Diagnostic (Postdoctoral Fellowship) (NCC958PF01402)
Principal Investigator
Research Area:
Species Studied
Scientific Name: Rattus norvegicus Species: Rat

The otolith organs, the utricle and saccule, play a role in a number of clinical vestibular disorders and have been hypothesized to play a role in some of the vestibular dysfunction experienced by astronauts during space flight and after re-entry. The mammalian saccule, which senses gravity, accelerations, and loud acoustic stimuli, is one of the least studied organs of the inner ear. Although there are morphological changes in the saccular epithelium (to both type I and type II hair cells) as a result of space flight, little is understood about how these changes might affect saccular physiology. Improving our understanding of the saccule and its frequency characteristics is of particular interest because measurements of saccular sensitivity in response to loud sounds are starting to be used in the clinic. The goal of this study was to improve the understanding of the mammalian saccule by focusing on the frequency characteristics of the saccular epithelium. The original study had two aims. The first aim was to characterize the frequency tuning of saccular reflexes in response to tones using both vestibular evoked myogenic potentials, and vestibulo-ocular reflexes in adult rats. The second aim was to evaluate the frequency characteristics of saccular hair cells by receptor potentials and transduction currents from the central (striolar) and peripheral (extrastriolar) zones of the saccular epithelium. Based on preliminary results from both aims, the investigators decided to focus their efforts on the second aim. The investigators hypothesize that within the saccular epithelium hair cell frequency sensitivity will vary with hair cell type and zone, with some cells sensitive to higher frequency stimuli, including acoustic frequencies and others sensitive to lower frequencies, including frequencies of voluntary head motions.

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Eatock RA and Songer JE. Vestibular hair cells and afferents: two channels for head motion signals. Annual Review of Neuroscience. 2011; 34:501-34.[]

Eatock RA, Kalluri R, and Songer JE. The organization of signals in mammalian otolith organs. 33rd MidWinter Meeting, Association for Research in Otolaryngology, Anaheim, California, February 6-10, 2010.

Songer JE and Eatock RA. Frequency characteristics of the mammalian saccular epithelium. NASA Human Research Program Investigators' Workshop, Houston, Texas, February 3-5, 2010.

Adaptation, physiological
Hair cells, vestibular
Signal transduction

Data Information
Data Availability
Archive is complete. No data sets are available for this experiment. Please Contact LSDA if you know of available data for this investigation.

Extrastriolar type II hair cells
Striolar type I hair cells

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
National Space Biomedical Research Institute (NSBRI)
Proposal Source
2007 NSBRI-RFA-07-02 Postdoctoral Fellowships