Purchase this article with an account.
J.L. Semmlow, T.L. Alvarez, C. Pedrono; Divergence Responses to Smoothly Moving Targets . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2539.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Oculomotor responses to targets moving smoothly and symmetrically inward (i.e., convergence eye movements) depend on target velocity: slowly moving stimuli produce smooth tracking movements while faster stimuli produce a sequence of step–like responses. This study documents the vergence response to similar diverging stimuli. Methods: A diverging ramp stimulus of 6 deg/sec was given to three subjects and their eye movements were recorded using an infrared limbus–tracking device. Two subjects began at an initial near fixation position of 20 deg and the third at 18 deg. Results: A diverging ramp stimulus of 6 deg/sec generated high–velocity, step–like responses similar to those seen in convergence movements. The peak velocities of these step–like behaviors systematically decreased as the target become more distant from the subjects (see table). Discussion: The divergence response to targets moving smoothly away from a subject shows step–like behavior similar to that seen in convergence responses to the same stimuli. Convergence step–like behavior has been attributed to the action of a transient control component operating in the context "Dual–Mode" control structure. The similar behavior seen in divergence suggests a similar control structure. The decrease in step dynamics as the target recedes could be related to a nonlinearity in a motor component as similar position–dependent behavior was found in divergence step responses. Conclusion: Divergent eye movement response to smoothly moving stimuli shows step–like behavior similar to that seen in convergence. The speed of these steps decreases as the target moves outward. Acknowledgement:This research was funded from Essilor International. Peak Velocity (deg/sec) for the Step–Like Responses found in Diverging Ramps
This PDF is available to Subscribers Only