What is optokinetic movement?
Optokinetic nystagmus is a rhythmic involuntary conjugate ocular movement in response to the movement of full visual field images, either rotation of an image before the subject, such as a drum with vertical black stripes on a white background, or rocking of a mirror back and forth in front of the patient’s eyes.
What is the purpose of Optokinetic nystagmus?
Purpose of the optokinetic nystagmus test The optokinetic reflex allows the eyes to follow objects in motion while the head remains stationary. This function is performed within the central vestibular system.
What is the difference between the vestibulo ocular reflex and an optokinetic response?
In VOR, turning the head stimulates the vestibular organ, resulting in turning of the eyeball in the direction opposite to the head turn. In OKR, movement of the large visual field (optokinetic stimulation) induces the eyeball to turn in the same direction as the image motion.
Where are the sensors for Optokinetic nystagmus?
In the case of the vestibulo-ocular reflex, when the head moves to the right, “vestibular” sensors in the inner ear are triggered and signal nuclei in the horizontal and vertical gaze centers of the brainstem to create an equal and opposite eye velocity signal.
What is a Optokinetic nystagmus test?
Optokinetic nystagmus (OKN) is a physiologic phenomenon produced by asking the patient to visually track a succession of moving stimuli. OKN eye movements involve two phases: the first is smooth pursuit eye movements in the direction of the moving target and the second is nystagmus in the contralateral direction.
What is the Vestibulocollic reflex?
The Vestibulocollic Reflex (VCR) The vestibulocollic reflex acts on the neck musculature in order to stabilize the head. Reflex head movement counters the movement sensed by the otoliths or semicircular canals. The neural pathways mediating this reflex are as yet uncertain.
What is Optokinetic nystagmus test?
What is the optokinetic reflex?
The optokinetic reflex (OKR), which serves to stabilize a moving image on the retina, is a behavioral response that has many favorable attributes as a test of CNS function.
How to evoke optokinetic and optomotor reflexes in mice?
To evoke Optokinetic and Optomotor reflexes in mice the animal is typically placed in the center of a cylinder or sphere that is covered with a repetitive pattern, such as stripes ([Thaung et al., 2002], [Abdeljalil et al., 2005]), sinusoidal gratings (Prusky et al., 2004), or random dots (Dubois and Collewijn, 1979).
What does optokinetic stimulus look like?
A strong optokinetic stimulus (4° wide black and white stripes rotating at 5°/second) was continuously displayed during the 15–20 minute recording session.
How do unrestrained mice respond to visual stimuli?
Unrestrained mice combine head and eye movements to respond to visual stimuli, and both monocular and binocular fields are used during optokinetic responses. Mouse OMR and OKR movements are heterogeneous under optimal and suboptimal stimulation and are affected in mice lacking ON direction-selective retinal ganglion cells.