24-Motor5-Eye Flashcards
ballistic movement
once initiated, cannot be modified
Fovea is ___ mm wide on retina, covers about ___ degrees of central vision
2,2
Why are saccades necessary?
- Have to reposition fovea to sample important parts of image
- But eye needs to be stationary to resolve clear image
- Therefore saccades move as quickly as possible then freeze
Approximate duration of saccades
20-50 ms
Peak velocity scales with saccade ___
amplitude
true
Chain of descending saccade control (x5)
- Cerebral cortex (voluntary saccade command of direction and amplitude)
- Superior colliculus (reflexive saccades, head movements)
- Brainstem saccade generator (computes commands for individual muscles)
- Motor neurons (abducens, oculomotor, trochlear nuclei)
- Eye muscles (horiz: medial,lateral rectus; vert: superior, inferior retus)
false
Site of translation from abstract saccade direction/amplitude to individual muscle signals
Brainstem saccade generator
Cranial nerves involved in saccade output
- abducens
- oculomotor
- trochlear
Eye muscles of horizontal movement
medial and lateral rectus
Eye muscles of vertical movement
superior and inferior rectus
Superior rectus activation leads to ___ of eye
elevation
Inferior rectus activation leads to ___ of eye
depression
Medial rectus activation leads to ___ of eye
adduction
Lateral rectus activation leads to ___ of eye
abduction
Motor nucleus of superior rectus
oculomotor
Motor nucleus of medial rectus
oculomotor
Motor nucleus of inferior rectus
oculomotor
Motor nucleus of lateral rectus
abducens
Regions in cortical eye fields (x3)
- frontal eye fields (FEF)
- lateral intraparietal (LIP)
- supplementary eye fields (SEF)
FEF
frontal eye fields