Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6274569 | Neuroscience | 2013 | 9 Pages |
Abstract
To discriminate between these two possibilities we used a real target paradigm with vergence angle coupled to distance and a virtual target paradigm with vergence angle dissociated from target distance. We compared TVOR responses in six subjects who underwent lateral sinusoidal whole-body translations at 1 and 2Â Hz. Real targets varied between distance of 50 and 22.4Â cm in front of the subjects, whereas the virtual targets consisting of a green and red light emitting diode (LED) were physically located at 50Â cm from the subject. Red and green LED's were dichoptically viewed. By shifting the red LED relative to the green LED we created a range of virtual viewing distances where vergence angle changed but the ideal kinematic eye velocity was always the same. Eye velocity data recorded with virtual targets were compared to eye velocity data recorded with real targets. We also used flashing targets (flash frequency 1Â Hz, duration 5Â ms). During the real, continuous visible targets condition scaling of compensatory eye velocity with vergence angle was nearly perfect. During viewing of virtual targets, and with flashed targets compensatory eye velocity only weakly correlated to vergence angle, indicating that vergence angle is only partially coupled to compensatory eye velocity during translation. Our data suggest that in humans vergence angle as a measure of target distance estimation has only limited use for automatic TVOR scaling.
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Authors
J. Dits, W.M. King, J. van der Steen,