title: Neural response in vestibular organ of Helix aspersa to centrifugation and re-adaptation to normal gravity.
abstract: Gravity plays a key role in shaping the vestibular sensitivity (VS) of terrestrial organisms. We studied VS changes in the statocyst of the gastropod Helix aspersa immediately after 4-, 16-, and 32-day exposures to a 1.4G hypergravic field or following a 7-day recovery period. In the same animals we measured latencies of behavioral "negative gravitaxis" responses to a head-down pitch before and after centrifugation and found significant delays after 16- and 32-day runs. In an isolated neural preparation we recorded the electrophysiological responses of the statocyst nerve to static tilt (±19°) and sinusoids (±12°; 0.1 Hz). Spike sorting software was used to separate individual sensory cells' patterns out of a common trace. In correspondence with behavior we observed a VS decrease in animals after 16- (p < 0.05) and 32-day (p < 0.01) centrifugations. These findings reveal the capability of statoreceptors to adjust their sensitivity in response to a prolonged change in the force of gravity. Interestingly, background discharge rate increased after 16 and 32 days in hypergravity and continued to rise through the recovery period. This result indicates that adaptive mechanisms to novel gravity levels were long lasting, and re-adaptation from hypergravity is a more complex process than just "return to normal".
authors: Space Biosciences Research Branch, NASA Ames Research Center, Mail stop 239-11, Moffett Field, Mountain View, CA, 94035, USA.
authors: Yekaterina
authors: Y
authors: Popova
authors: Richard
authors: R
authors: Boyle
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000200:Action Potentials; D000818:Animals; D017952:Ganglia, Invertebrate / Q000502:physiology*; D018466:Gravity Sensing / Q000502:physiology*; D006372:Helix, Snails / Q000502:physiology*; D018471:Hypergravity; D008839:Microelectrodes; D009043:Motor Activity / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009949:Orientation / Q000502:physiology; D011187:Posture / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013997:Time Factors; D046509:Tissue Culture Techniques