Torsional optokinetic nystagmus: normal response characteristics

Background/aims: Few studies have investigated normal response characteristics of torsional optokinetic nystagmus (tOKN). The authors have investigated the effect of stimulus velocity and central/peripheral stimulation on tOKN. Methods: Torsional OKN was elicited using a sinusoidal grating rotating at velocities of 3°/s to 1000°/s in clockwise and anticlockwise directions. To investigate the effect of central stimulation, stimulus size was varied from 2.86° to 50.8°. An artificial scotoma placed over a 50.8° stimulus was varied from 2.86° to 43.2° to investigate peripheral stimulation. Eight subjects participated in each experiment and torsional eye movements were recorded using video-oculography. The mean slow phase velocity (MSPV) and gain were calculated. Results: The maximum gain occurred in response to 8°/s stimulation. The MSPV increased up to a stimulus velocity of 200°/s achieving a maximum of 3°/s in both directions. MSPV was linearly correlated with the log of stimulus velocity. The smallest field size, rotating at 40°/s, evoked 10% of the gain elicited by the largest display. When the most peripheral stimulus was used, the gain was maintained at 50% of the gain evoked when the full display was used. Conclusions: A wide range of stimulus velocities can elicit tOKN and peripheral field stimulation contributes significantly to its response.

[1]  Stimulus velocity dependence of human vertical optokinetic nystagmus and afternystagmus. , 1992, Journal of vestibular research : equilibrium & orientation.

[2]  A. Hendrickson,et al.  Human photoreceptor topography , 1990, The Journal of comparative neurology.

[3]  E. Peitersen,et al.  The significance of the target frequency and the target speed in optokinetic nystagmus (OKN). , 1979, Acta oto-laryngologica.

[4]  L. Pessoa,et al.  Filling-in: From perceptual completion to cortical reorganization. , 2003 .

[5]  J. Sharpe,et al.  The effects of head and trunk position on torsional vestibular and optokinetic eye movements in humans , 2004, Experimental Brain Research.

[6]  Y. Shinmei,et al.  Effects of a fixation target on torsional optokinetic nystagmus. , 2000, Investigative ophthalmology & visual science.

[7]  I. Howard,et al.  Cycloversion and cyclovergence: the effects of the area and position of the visual display , 1994, Experimental Brain Research.

[8]  H. Collewijn,et al.  Human ocular counterroll: assessment of static and dynamic properties from electromagnetic scleral coil recordings , 2004, Experimental Brain Research.

[9]  Masao Ohmi,et al.  The efficiency of the central and peripheral retina in driving human optokinetic nystagmus , 1984, Vision Research.

[10]  I. P. Howard,et al.  Optokinetic torsion: Dynamics and relation to circularvection , 1991, Vision Research.

[11]  I. Gottlob,et al.  Optokinetic nystagmus elicited by filling-in in adults with central scotoma. , 2002, Investigative ophthalmology & visual science.

[12]  I. Gottlob,et al.  Optokinetic nystagmus in patients with central scotomas in age related macular degeneration , 2001, The British journal of ophthalmology.

[13]  Richard V Abadi,et al.  Monocular optokinetic nystagmus in humans with age-related maculopathy , 1997, The British journal of ophthalmology.

[14]  A. Bronstein,et al.  Torsional eye movements are facilitated during perception of self-motion , 1999, Experimental Brain Research.