Three-dimensional optokinetic eye movements in the C57BL/6J mouse

Area of Science:

• Oculomotor physiology
• Neuroscience
• Vision science

Background:

• Optokinetic eye movements are reflexive, gaze-stabilizing responses crucial for minimizing retinal image slip.
• These movements are vital for motor control and learning, serving as a prominent model system.
• Three-dimensional optokinetic eye movements encompass horizontal, vertical, and torsional components.

Purpose of the Study:

• To investigate the three-dimensional optokinetic eye movements in wild-type C57BL/6J mice, a standard model in oculomotor research.
• To characterize the input-output relationship and directional uniformity of these eye movements.
• To compare marker tracking with pupil tracking for assessing horizontal optokinetic responses.

Main Methods:

• Eye movements were induced using a virtual sphere of dots rotated sinusoidally at frequencies from 0.1 to 1 Hz (5-degree amplitude).
• Three-dimensional eye movements were recorded using video oculography with markers applied to the mouse eye.
• Marker tracking was validated against conventional pupil tracking for horizontal optokinetic responses.

Main Results:

• Marker and pupil tracking methods yielded comparable results for gain measurements.
• Optokinetic eye movements in mice were found to be equally developed in horizontal, vertical, and torsional directions.
• Stimuli evoking torsional eye movements showed gains near unity with minimal phase differences, indicating effective compensation.

Conclusions:

• C57BL/6J mice demonstrate effective compensation for image motion across the retina via optokinetic eye movements, irrespective of stimulus orientation.
• Responses are dependent on stimulus frequency and velocity, with decreasing gains and increasing phase lags at higher frequencies.
• Mice exhibit significant torsional responses, particularly at lower stimulus frequencies, highlighting the three-dimensional nature of this reflex.