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18 Cards in this Set

  • Front
  • Back
What are saccades?
Very rapid, conjugate eye movements as the eyes are targeting an "object".
What area of the brain drives voluntary saccades?
Frontal eye field of the cerebral cortex drives voluntary movements.
What area of the brain collects three inputs and drives non-voluntary saccades. What are the three inputs to it?
Superior colliculus drives reflex movements in response to signals from the retina, somatosensory system, and auditory system.
What is the center for lateral gaze?
PPRF (parapontine reticular formation) located in the pons region.
What is the circuit for a saccade - voluntary left lateral gaze?
Right frontal eye field -> Left superior colliculus -> left pprf -> left CN VI (to its muscle) -> MLF -> CN III (to its muscle)
What is the circuit for a saccade - involuntary left lateral gaze?
Right Visual signal from retina OR right auditory signal OR right somatosensory signal -> Left superior colliculus -> left pprf -> left CN VI (to its muscle) -> MLF -> CN III (to its muscle)
What nucleus is involved in a saccade in vertical gaze?
riMLF (rostral interstial nucleus of MLF)
What is distinctive about the location of the horizontal gaze nucleus versus the vertical gaze nucleus?
PPRF (Horz) in caudal pons. riMLF in midbrain and does not require circuitry caudal to it.

riMLF has some bi-lateral innervation of occular muscles and some ipsilateral. These pieces of info can help to sort out the location of a leison.
Describe smooth pursuit.
The objective is to keep a moving target on the fovea ("targeting").
Diagram the circuit for horizontal smooth pursuit to the right)
Right Frontal eye fields and extrastriate cortex -> dorsolateral pontine nuclei -> left cerebellum (flocculus and posterior vermis) -> vestibular nucleus -> left VI (to its muscle) -> MLF -> right III (to its muscle)
Describe vergence
Vergence is a general term referring to the movement of convergence or divergence of the eyes.
What cranial nerves mediate vergence?
What is the near response/near triad?
Near response/near triad: eyes converge, pupils constrict, and the lens changes shape.
Which cranial nerve(s) mediate each part of the near response?
Describe optokinetic movements.
Optokinetic movements will consist of two parts: watching a moving, constant velocity object until to goes out of visual field, snapping the gaze to a new target.
What is an example of an optokinetic movement?
Watching train cars as a train passes. We might watch one car until it goes out of sight then switch to another car.
How are optokinetic movements like vestibular Nystagmus?
There is a slow phase (the smooth pursuit) alternating with a fast phase (saccade).
How are optokinetic movements different than vestibular Nystagmus? Include a comment relating to acceleration and velocity.
Optokinetic movements are driven by visual input rather than vestibular information (position of head), and this has a constant velocity versus acceleration in the vestibular case.