Affiliations: [a] Department of Otolaryngology–Head & Neck Surgery, Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA | [b] Department of Otolaryngology–Head & Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA | [c] Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
Abstract: Previous studies established that vestibular reflexes can have two adapted states (e.g., gains) simultaneously, and that a context cue (e.g., vertical eye position) can switch between the two states. Our earlier work demonstrated this phenomenon of context-specific adaptation for saccadic eye movements: we asked for gain decrease in one context state and gain increase in another context state, and then determined if a change in the context state would invoke switching between the adapted states. Horizontal and vertical eye position and head orientation could serve, to varying degrees, as cues for switching between two different saccade gains. In the present study, we asked whether gravity magnitude could serve as a context cue: saccade adaptation was performed during parabolic flight, which provides alternating levels of gravitoinertial force (0 g and 1.8 g). Results were less robust than those from ground experiments, but established that different saccade magnitudes could be associated with different gravity levels.
Keywords: saccades, physiological adaptation, context, learning, gravity, human
