Completed - Task completed and produced a deliverable
The central nervous system must resolve the ambiguity of inertial motion sensory cues in order to derive an accurate representation of spatial orientation. Adaptive changes during spaceflight in how the brain integrates vestibular cues with other sensory information can lead to impaired movement coordination, vertigo, spatial disorientation and perceptual illusions following G-transitions. This investigation examines whether adaptive changes in otolith function has operational implications for manual control performance following short-duration flights.
The ZAG specific aims for this pre- and post-flight study include: (1) measure changes in eye movements and perception in response to different combinations of tilt and translation motion, (2) measure changes in closed-loop nulling of tilt motion disturbances, (3) evaluate whether a vibrotactile sensory substitution can improve manual control of orientation. The Otolith specific aims include: (1) assess changes in otolith ocular reflexes and subjective visual vertical during unilateral centrifugation, and (2) assess changes in vestibulo-collic reflexes during Vestibular Evoked Myogenic Potential (VEMP) testing.
Both experiments utilize constant velocity Variable Radius Centrifugation in darkness to elicit otolith reflexes in the absence canal or vision. ZAG also utilizes the Tilt-Translation Sled paradigm in which the resultant vector remains aligned with the longitudinal body axis, resulting in mismatch between canal and vision cues which indicate tilt while otolith cues do not.
The expected results will include a quantitative assessment of acute changes in otolith-mediated reflexes, and the time course of recovery following short-duration spaceflight.
How task will fill or partially fill the gap
This study will correlate individual vestibular changes with manual performance during closed-loop nulling of tilt disturbances, both with and without the aid of a tactile prosthesis.