Vision and Audition Flashcards
Lecture 2 Exam 3 (45 cards)
Oculomotor system eye movements: slow conjugate movements to follow a target
smooth pursuits
Oculomotor system eye movements: rapid small conjugate movements that change point of fixation
saccades
Oculomotor system eye movements: eye movements that compensate for head rotation
VOR
Oculomotor system eye movements: slow, disconjugate eye movements to change focal distance
vergence
Oculomotor system eye movements: small, involuntary movements necessary for vision (fill in blind spot)
miniature eye movements
For conjugate movements, must activate _____ lateral rectus and _____ medial rectus
left; right
Conjugate movements are simultanous activation of the left ____ and right ______ nuclei, triggered by abducens
abducens; oculomotor
What nuclei does the medial longitudinal fasciculus connect
abducens and oculomotor
Example of a vergence movement: called _____ reflex
accommodation
Is setting a fixation point usually conscious decision in the vergence movement?
yes but changing the lens is not under conscious control
What three things must occur to switch from a far-off focal point to a very near focal point
- convergence
- constriction of pupil
- contraction or constriction of ciliary muscles and lens
Do accommodations of the eye require cortical feedback?
yes
VOR automatically produces slow eye movement in the direct ________ direction to head movement
opposite
What does VOR rely on for input
input from the vestibular system, semicircular canals
_____ is a combo of slow movements and quick saccades
nystagmus
Nystagmus is an _____ reflex movement to keep the image focused in place on the retina
automatic
What can we thank for the ability of Nystagmus to have an auto-reflex movement to keep images focused in place on the retina
direction-selective retinal ganglion cells
What is optokinetic nystagmus
when an object or scene passes by with a steady speed
________ nystagmus is the automatic nystagmus of the eyes in response to the rotation of fluid inside the semicircular canals
vestibular
What is the overall purpose of the VOR circuit
to stabilize vision incredibly quickly to keep the image sharp
The semicircular canals report on angular velocity but eyes are small and located further away from the center of the head than the canals, how do we make up for this
VOR gain
What is the equation for VOR gain?
change in eye angle/ change in head angle during head turn
What does the Paramedian pontine reticular formation do
-saccade generator
-provide input to the abducens nucleus
-complex calculations for horizontal gaze correction
________ pathway: retina to the superior colliculus, to pulvinar of the thalamus, to V2 cortex
tectopulvinar pathway