Lecture 5 - Eye Movements

Question 1

What is the vestibulo-ocular reflex VOR?

Answer 1

-reflex controlled by the cerebellum and other vestibular nuclei which is repsonsible for maintaining a stable visual field during rotation movements
-the extraocular muscles of the eye will work to move the eyes in the opposite direction of rotation
-uni or bilateral lesions to any key synaptic points in the VOR circuitry will result in drifting of the eyes in the same direction of rotation

Question 2

What are the three cranial nerves responsible for innervating the extraocular muscles of the eye?

Answer 2

CN III - oculomotor nerve
CN IV - trochlear nerve
CN VI - abducens nerve

Question 3

What does the oculomotor nerve innervate?

Answer 3

4 of the six extraocular muscles and communicates with the Edinger-Westphal Nucleus in the midbrain to control the pupillary light reflex

-superior, medial, and inferior recti
-inferior oblique

Question 4

What does the trochlear nerve innervate?

Answer 4

one of the six extraocular muscles and it exits from the dorsal side of the brainstem
-superior oblique

Question 5

What does the abducens nerve innervate?

Answer 5

• one of the six extraocular muscles - responsible for the abducting eye - lateral rectus

Question 6

What are saccades and by what structures are they controlled by?

Answer 6

-basal ganglia and other cortical or subcortical structures controls saccades
-the are voluntary and involuntary eye movements which are repetitive

Question 7

When are saccades voluntary?

Answer 7

when deliberately focusing on an object in a visual field

Question 8

When are involuntary saccades?

Answer 8

repetitive horizontal saccades when reading

Question 9

What are the three types of saccades?

Answer 9

horizontal, vertical, oblique

Question 10

What role does salience play in human and monkey eye movement?

Answer 10

humans and monkeys have longer for fixed eye movements when they recognize the face of either a fellow human or monkey

Question 11

What have advances in eye tracking technology allowed for?

Answer 11

they have allowed scientists to show that eye movements can be revealing of cognition and attention

Question 12

What is nystagmus?

Answer 12

atypical saccades that are seen in patients with cerebellar regions and the deficit is characterized by repetitive saccades even when an individual is focusing or fixating which can have a negative effect on motor coordination and balance