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Peaks and troughs of three-dimensional vestibulo-ocular reflex in humans.

Goumans J, Houben MM, Dits J, van der Steen J - J. Assoc. Res. Otolaryngol. (2010)

Bottom Line: Vestibulo-ocular responses only partially fulfill this ideal behavior.In the dark and in response to transients, gain of all components had lower values.In combination with the relatively low torsion gain, this horizontal component has a relative large effect on the alignment of the eye rotation axis with respect to the head rotation axis.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Erasmus University Medical Centre Rotterdam, Rotterdam, The Netherlands.

ABSTRACT
The three-dimensional vestibulo-ocular reflex (3D VOR) ideally generates compensatory ocular rotations not only with a magnitude equal and opposite to the head rotation but also about an axis that is collinear with the head rotation axis. Vestibulo-ocular responses only partially fulfill this ideal behavior. Because animal studies have shown that vestibular stimulation about particular axes may lead to suboptimal compensatory responses, we investigated in healthy subjects the peaks and troughs in 3D VOR stabilization in terms of gain and alignment of the 3D vestibulo-ocular response. Six healthy upright sitting subjects underwent whole body small amplitude sinusoidal and constant acceleration transients delivered by a six-degree-of-freedom motion platform. Subjects were oscillated about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5 degrees in azimuth. Transients were delivered in yaw, roll, and pitch and in the vertical canal planes. Eye movements were recorded in with 3D search coils. Eye coil signals were converted to rotation vectors, from which we calculated gain and misalignment. During horizontal axis stimulation, systematic deviations were found. In the light, misalignment of the 3D VOR had a maximum misalignment at about 45 degrees . These deviations in misalignment can be explained by vector summation of the eye rotation components with a low gain for torsion and high gain for vertical. In the dark and in response to transients, gain of all components had lower values. Misalignment in darkness and for transients had different peaks and troughs than in the light: its minimum was during pitch axis stimulation and its maximum during roll axis stimulation. We show that the relatively large misalignment for roll in darkness is due to a horizontal eye movement component that is only present in darkness. In combination with the relatively low torsion gain, this horizontal component has a relative large effect on the alignment of the eye rotation axis with respect to the head rotation axis.

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Plots of eye velocities projected on the roll, pitch, and yaw plane during sinusoidal stimulation about the roll axis in the light (upper panels) and in darkness (lower panels). The horizontal solid line corresponds to the x-axis shown in the cartoons in the upper panel. Far right panel Correlation between misalignment and the slope of the regression line fitted through eye velocity data obtained during roll stimulation in the dark projected on the pitch plane. Each data point represents one subject.
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Fig4: Plots of eye velocities projected on the roll, pitch, and yaw plane during sinusoidal stimulation about the roll axis in the light (upper panels) and in darkness (lower panels). The horizontal solid line corresponds to the x-axis shown in the cartoons in the upper panel. Far right panel Correlation between misalignment and the slope of the regression line fitted through eye velocity data obtained during roll stimulation in the dark projected on the pitch plane. Each data point represents one subject.

Mentions: Because the misalignment angle only gives the angle of deviation between head and eye rotation axis, we also plotted the angular velocities projected on the roll, pitch, and yaw planes. An example for stimulation about the x-axis (roll) is given in Fig. 4. The three top panels show that in the light, the angular velocities coincide with the x-axis for each plane. The contributions of yaw and pitch velocities are very small compared to the roll component. In darkness (lower panels), there is considerably more deviation between stimulus and response. There is a small but consistent horizontal velocity component in the dark (left and middle lower panels).FIG. 4


Peaks and troughs of three-dimensional vestibulo-ocular reflex in humans.

Goumans J, Houben MM, Dits J, van der Steen J - J. Assoc. Res. Otolaryngol. (2010)

Plots of eye velocities projected on the roll, pitch, and yaw plane during sinusoidal stimulation about the roll axis in the light (upper panels) and in darkness (lower panels). The horizontal solid line corresponds to the x-axis shown in the cartoons in the upper panel. Far right panel Correlation between misalignment and the slope of the regression line fitted through eye velocity data obtained during roll stimulation in the dark projected on the pitch plane. Each data point represents one subject.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2914236&req=5

Fig4: Plots of eye velocities projected on the roll, pitch, and yaw plane during sinusoidal stimulation about the roll axis in the light (upper panels) and in darkness (lower panels). The horizontal solid line corresponds to the x-axis shown in the cartoons in the upper panel. Far right panel Correlation between misalignment and the slope of the regression line fitted through eye velocity data obtained during roll stimulation in the dark projected on the pitch plane. Each data point represents one subject.
Mentions: Because the misalignment angle only gives the angle of deviation between head and eye rotation axis, we also plotted the angular velocities projected on the roll, pitch, and yaw planes. An example for stimulation about the x-axis (roll) is given in Fig. 4. The three top panels show that in the light, the angular velocities coincide with the x-axis for each plane. The contributions of yaw and pitch velocities are very small compared to the roll component. In darkness (lower panels), there is considerably more deviation between stimulus and response. There is a small but consistent horizontal velocity component in the dark (left and middle lower panels).FIG. 4

Bottom Line: Vestibulo-ocular responses only partially fulfill this ideal behavior.In the dark and in response to transients, gain of all components had lower values.In combination with the relatively low torsion gain, this horizontal component has a relative large effect on the alignment of the eye rotation axis with respect to the head rotation axis.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Erasmus University Medical Centre Rotterdam, Rotterdam, The Netherlands.

ABSTRACT
The three-dimensional vestibulo-ocular reflex (3D VOR) ideally generates compensatory ocular rotations not only with a magnitude equal and opposite to the head rotation but also about an axis that is collinear with the head rotation axis. Vestibulo-ocular responses only partially fulfill this ideal behavior. Because animal studies have shown that vestibular stimulation about particular axes may lead to suboptimal compensatory responses, we investigated in healthy subjects the peaks and troughs in 3D VOR stabilization in terms of gain and alignment of the 3D vestibulo-ocular response. Six healthy upright sitting subjects underwent whole body small amplitude sinusoidal and constant acceleration transients delivered by a six-degree-of-freedom motion platform. Subjects were oscillated about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5 degrees in azimuth. Transients were delivered in yaw, roll, and pitch and in the vertical canal planes. Eye movements were recorded in with 3D search coils. Eye coil signals were converted to rotation vectors, from which we calculated gain and misalignment. During horizontal axis stimulation, systematic deviations were found. In the light, misalignment of the 3D VOR had a maximum misalignment at about 45 degrees . These deviations in misalignment can be explained by vector summation of the eye rotation components with a low gain for torsion and high gain for vertical. In the dark and in response to transients, gain of all components had lower values. Misalignment in darkness and for transients had different peaks and troughs than in the light: its minimum was during pitch axis stimulation and its maximum during roll axis stimulation. We show that the relatively large misalignment for roll in darkness is due to a horizontal eye movement component that is only present in darkness. In combination with the relatively low torsion gain, this horizontal component has a relative large effect on the alignment of the eye rotation axis with respect to the head rotation axis.

Show MeSH
Related in: MedlinePlus