quiz #3- optic reflexes
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What do eye movements require synthesis of?
- head movements (vestibular)
- visual objects or info (visual)
- eye movement and position (proprioception)
- visual target selection (BS & cortex)
What are the goals of eye movements?
- place image on fovea of both retinas for acuity
- allow image perceoption as 1 through binocular vision
What are eye movement mediated through?
- superior colliculi
What are the 5 types of eye movement?
- vestibulo-ocular reflex
- optokinetic reflex
- smooth pursuit
What is the purpose of the vestibulo ocular reflex?
keeps visual world relatively stationary with fast head movement
How can the vestibulo-ocular reflex be suppressed?
by vestibulocerebellum to allow person to turn head and redirect eyes
What is the purpose of the optokinetic reflex?
- adjust eye position during slow head movements
- reflex through moving visual stimuli
- (car at stoplight is moving backwards, making you feel like you are moving forward)
What are the cortical centers for voluntary eye movement?
- frontal eye fields: voluntary eye movement (convergence type of movement)
- posterior parietal cortex: voluntary smooth pursuit eye movement
- occipital cortex & temporal eye fields: smooth pursuit eye movement
- dorsolateral prefrontal cortex: inhibit eye movement
What do paramedian pontine reticular formation do in terms of gaze direction?
voluntary horizontal sacades
What do abducens and oculomotor do in terms of gaze direction?
horizontal pursuit and reflexive saccades
What does the midbrain reticular formation do in terms of gaze direction?
vertical eye movements
What do cortical centers do in terms of gaze direction?
voluntary eye control
What is the purpose of reflexive saccades?
- direct eyes reflexively to visual tactile or auditory stimuli
- NO CORTICAL INPUT
What is the purpose of voluntary saccades?
direct eyes voluntarily to visual, tactile or auditory stimuli
What is the purpose of smooth pursuit?
- to voluntarily track an object moving across the visual field
- (ex. can't track how far to move in for a fly ball in baseball)
What would you like to do?
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