Lecture 11 Objectives

Question 1

What are the 6 functional classes of eye movements?

Answer 1

Saccades
Smooth pursuits
Vergences
Fixation
VOR
OKN

Question 2

What is the purpose of saccades?

Answer 2

To bring the image of an object rapidly onto the fovea

Question 3

What do smooth pursuits do?

Answer 3

Hold the image of a small moving target on the fovea

Question 4

What do vergences do?

Answer 4

Move the eyes in opposite directions so that images of a single object are held on both fovea

Question 5

What do vergences allow for?

Answer 5

Simultaneous perception

Question 6

What does fixation do?

Answer 6

Holds the image of a stationary object on the fovea when the head is immoble

Question 7

What does VOR do?

Answer 7

Holds an image steady on the retina during brief head movements

Question 8

What does OKN do?

Answer 8

Holds an image steady on the retina during sustained head movements, or when the environment moves around the head

Question 9

When doe OKN kick in?

Answer 9

When there is constant spin or speed

Question 10

What are the three directional classifications of movements?

Answer 10

Ductions
Versions
Vergences

Question 11

Which of the directional classifications of eye movements is primarily monocular?

Answer 11

Ductions

Question 12

What are the 3 axes of movement of ductions?

Answer 12

X = incyclotorsion/excyclotorsion
Y = elevation/depression
Z = abduction/adduction

Question 13

What brain structures are involved in gaze control?

Answer 13

Frontal eye fields (FEF)
Superior colliculus (SC)
Medial longitudinal fasciculus (MLF)
Paramedian pontine reticular formation (PPRF)
Interstitial nucleus of Caja (NIC)

Question 14

What is the pathway of information of gaze control?

Answer 14

Retina
Optic nerve
Optic tract
LGN
Frontal eye fields (FEF)
Superior colliculus (SC)
Horizontal and vertical gaze centers (PPRF and NIC)
Medial longitudinal fasciculus (MLF)
Cranial nerves 3, 4, and 6
EOMs

Question 15

Where does the output from the frontal eye fields (FEF) go?

Answer 15

Superior colliculus (SC)

Question 16

What are the frontal eye fields important for in gaze control?

Answer 16

Unguided eye movements

Scanning the visual field

Question 17

From where does the superior colliculus (SC) receive input?

Answer 17

Retina
Auditory system
Somatosensory system
Frontal eye fields

Question 18

Where does the output from the superior colliculus (SC) go?

Answer 18

Gaze centers

Question 19

What does the superior colliculus (SC) control in gaze control?

Answer 19

Direction and magnitude of saccades

Question 20

What is considered the horizontal gaze center?

Answer 20

Paramedian Pontine Reticular Formation (PPRF)

Question 21

Where is the PPRF located?

Answer 21

In the pons

Question 22

Where does the output from the PPRF go?

Answer 22

Nuclei of motor nerves for horizontal movement

Question 23

What is considered the vertical gaze center?

Answer 23

Interstitial nucleus of Cajal (INC)

Question 24

What does the interstitial nucleus of cajal control?

Answer 24

Vertical saccades and pursuits

Question 25

Where does the output from the interstitial nucleus of cajal go?

Answer 25

Nuclei of motor nerves for vertical movement

Question 26

What controls disjugate eye movements?

Answer 26

Vergence control

Question 27

What brain structures are included in vergence control?

Answer 27

FEF
PEF
MT/MST
Medial NRTP
SOA
Cerebellum

Question 28

What are the two control models found in gaze control?

Answer 28

Open loop

Closed loop

Question 29

Which type of control loop feeds output back into the input?

Answer 29

Closed loop

Question 30

What is an example of a movement under open loop control?

Answer 30

Saccadic movements

Question 31

What is an example of a movement under closed loop control?

Answer 31

Accommodation