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14 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are saccades?
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quick, darting movements that change point of fixation
--can be voluntary or involuntary --what initiates voluntary saccades? -what initiates reflex saccades? (turn to bright light, noise, or touch) |
--voluntary saccades are initiated by the FEFs
--reflex saccades are initiated by superior colliculus ----superior colliculus also projects to the cervical SC via tectospinal pathway; therefore can turn head/neck if needed |
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What are smooth pursuit movements?
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tracking movements that keep moving stimulus on fovea
--a kind of 'reflex' bc we can't do it without following something |
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what is vergence?
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movements which allow the fovea of each eye to be aligned with objects at a specific distance.
--convergent mvmts allow eyes to fixate on nearer object, while divergent allow eyes to fixate on distant object -NON-CONJUGATE - eyes move in diff directions rather than same. |
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what is vestibulo-ocular reflex?
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rotation of head in one direction causes eyes to rotate at equal speed in opp direction
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what is optokinetic reflex?
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ie looking out window of car.
--part of scene moving fast. fixate on object and follow with smooth pursuit movment and then saccade to new object optokinetic nystagmus - slow movment in one direction and then fast saccade in other direction vestibulo-ocular and optokinetic reflexes work together to stabilize visual image. |
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what is fixation (on a stationary object)?
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active system
- superior colliculus |
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eye muscle innervation
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SO4 LR6 R3
4 is crossed and so is the nucleus serving superior rectus |
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rotational movements of eyes
intorsion extorsion |
intorsion = top of eye toward nose
extorsion = top of eye away from nose |
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where are the horizontal gaze centers located?
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paramedian Pontine reticular formation (PPRF)
--near midline in pons, close to abducens nucleus |
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where are vertical gaze centers located?
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rostral interstitial nucleus of MLF (riMLF)
-rostral midbrain oblique mvmts occur by both centers being activated to varying degree |
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What is internuclear ophthalmoplegia?
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lesion of MLF
characteristic in MS which causes scattered areas of demyelination --when patient asked to look to the side with the lesion; the opposite eye does not follow. ie. if left MLF damaged and you ask patient to look to the right. the right eye will abduct but the left eye will not adduct. but if you ask patient to converge. the left eye will adduct as will the right eye. |
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What are the four centers that control saccades?
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1. superior colliculus
2. FEF - Brodman's area 8 3. supplementary eye field 4. parietal eye field - impt for visual attenuation |
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what projects directly to the gaze centers?
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the (L) superior colliculus which receives input from contralateral visual field (R) --since it is 'seeing' the R side, it will project to the R PPRF
--also FEFs project directly to the gaze centers as well as the superior colliculus |
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Where does neural control of smooth pursuit movment come from?
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smooth pursuit = tracking a moving target
--visual cortex and FEF and parietal eye fields. as well as cerebellum. |
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