Transcript Oculomotor Systems

Oculomotor Systems
S. J. Potashner, Ph.D
[email protected]
Eye Motor Systems
Control tears & blinking – protects the eye surface
Control pupils – light compensation; sympathetic response
Control gaze & lens curvature – moves eyes onto a target
• Saccades
• Smooth pursuit
• Vergence
Control gaze during head movement – stabilize eyes on target
Pupillary Control System
Parasympathetic
Stimulus: light
Response: pupil constricts
video
Sympathetic
Stimulus: an event or memory
Response: pupil dilates,
lids open wider
video
Eye Movements
Fixation
holds foveas still
Saccade
shifts both foveas to an alternate target
Smooth pursuit
keeps both foveas on a moving target
Vergence
keeps both foveas on an approaching or
receding target
Optokinetic
keeps both foveas on target during head
movement
Control of Horizontal Saccadic Eye Movements
video
Control of Vertical Saccadic Eye Movements
video
Upper Motor Neurons That Control Saccads
Voluntary
pathway
Reflexive
pathways
Eye Movements
Fixation
holds foveas still
Saccade
shifts both foveas to an alternate target
Smooth pursuit
keeps both foveas on a moving target
Vergence
keeps both foveas on an approaching or
receding target
Optokinetic
keeps both foveas on target during head
movement
Control of Smooth Pursuit Eye Movements
video
Control of Vergence Eye Movements
Convergence
• Activation of both
medial rectus muscles
• Lens curvature increased
• Pupil constricts
video
Divergence
?
Control of Vergence Eye Movements
Interaction of Vergence and Saccades
saccade
vergence
before saccade
vergence
during saccade
vergence
after saccade