Neuroscience Week 5: Gaze Disorders Flashcards
Horizontal gaze centers location
Paramedian pontine reticular formation (PPRF)
Vertical gaze centers location
Dorsal Midbrain
VOR AKA
Vestibuloocular reflex
PPRF AKA
Paramedian Pontine Reticular Formation
The PPRF is controlled by?
Contralateral Frontal Eye Field in the frontal cortex

Stimulation of the LEFT frontal eye field in the cortex will activate?
The RIGHT PPRF, which stimulate coordinated, simultaneous movement of both eyes to the right
Right lateral rectus
and
left oculomotor to stimulate medial rectus through the MLF

Stimulation of the RIGHT frontal eye field in the cortex will activate?
The LEFT PPRF, which stimulate coordinated, simultaneous movement of both eyes to the left
Causes right oculomotor nerve to contract medial rectus through the MLF
and
simultaneous contraction of the left abducens lateral rectus

MLF AKA
Medial Longitudinal Fasciculus

Intranuclear opthalmoplegia (INO)
often the first symptom in MS!
Image is Left INO (disruption of the Left MLF)

often the first symptom in MS!
Intranuclear Opthalmoplegia (INO)
Left INO looking right
right eye Horizontal nystagmus on rightward gaze
left eye doesn’t move past midline on rightward gaze

Right INO looking Left
Left eye Horizontal nystagmus on leftward gaze
right eye doesn’t move past midline on leftward gaze
Common causes of IMO
3 listed
- Multiple Sclerosis
- pontine infarcts
- neoplasms involving the MLF
Gaze disorders of gazing right
LEFT FEF drift toward side of lesion
LEFT frontal eye field drives right PPRF

Lesion #1


Lesion #2


Lesion #3


Lesion #4


PPRF has unilateral/bilateral innervation
Mostly unilateral but has some bilateral innervation so overtime the unlesioned side can take over
Question 1

C.
if convergence is normal but there is the inability to adduct an eye during left or right gaze
Think MLF because convergence pathways are also in the dorsal midbrain so it is an INO
PPRF
Lesion in the left FEF involving left corticospinal tract, maybe MCA artery, will cause
eyes drift toward the side of the lesion and away from the weakness

Lesion in the pons where the PPRF is, including corticospinals, will cause
eyes will drift away from the lesion and toward the side of the weakness








