Control of eye movements (pt 2)

smooth pursuits track _____ moving objects (under ____degrees/sec)

slowly 100

smooth pursuits involve integration of what 4 things?

cortical information, cerebellar information, vestibular information, CN VI and III via MLF

____ DO NOT orient eyes toward a target, they KEEP THE TARGET ON THE FOVEA

pursuits

neural wiring for smooth pursuits is _______, but both sides of the ____ are active at the same time (allows us to keep object centered on fovea)

ipsilateral cortex

during a smooth pursuit, the visual cortex projects to _______/_______/______ junction (MT and MTS areas) ----> ______ FEF -----> ipsilateral _______ ______ ----> DECUSSATE and enter _______ cerebellum ------> ipsilateral vestibular nuclei ------> ______ CN VI nucleus

parietal occipital temporal ipsilateral pontine nuclei contralateral ispilateral

two phases of pursuits

closed and open loop

open loop phase of pursuit - response influenced only by _____ _____ of target

initial view

closed loop of pursuit - eye responds to _____ in ____ _____ produced by eye movements

alterations retinal image

initial acceleration of pursuits is ____ ____. After pulse of innervation, system receives feedback via the retinal image and the _____ ____ adjusts the velocity of eye movements

open loop closed loop

latency of pursuit initiation is ____msec

130

_____ are all about position

_____ area all about velocity

saccades pursuits

anterior canal of vestibular system moves eyes _____,

innervates _____ ___, _____ _____

upward ipsilateral SR, contralateral IO

posterior canal of vestibular system moves eyes _____

innervates _____ _____, _____ _____

downward ipsilateral SO, contralateral IR

horizontal canal of vestibular system moves eye ______

innervates ______ ____ and _____ ____

laterally ipsilateral MR and contralateral LR

_________ ______ - adjusts head movements so that gaze can remain fixed on an object even though head is moving (keeps retinal image stable)

vestibuloocular reflex

Head movements are detected by _____ ____ in _____ ____

vestibular organ inner ear

________ - rapid, rhythmic, to and fro eye movements

nystagmus

nystagmus often consists of ____ ____ (nomenclature) and ____ ____

fast phase slow drift

nystagmus can occur in ANY axis of eye movement, but _____ is most common

horizontal

nystagmus can be _______ or ________ (vestibular and OKN)

pathological physiological

COWS stands for...

cold opposite, warm same

stimulation of _______ ______ by inducing movement of endolymph in inner ear:

movement is elicited by irrigation of ______ _____ _____ with warm or cold water

vestibular nystagmus external auditory canal

warm temperature in external auditory canal sets up a ______ _____ in temporal bone

temperature gradient

_____ endolymph is denser than ______ endolymph

cold warm

caloric testing is performed with patient _____, head ___degrees from horizontal plane

supine 30

cold water in the right ear will cause movement of endolymph in _____ direction in _____ canal. VOR moves eyes to the _____, causing a _____-beat nystagmus

clockwise horizontal right left