Week 4

Question 1

WIT: Allows for rapid change of eye position; fastest speed om eye movement system

Answer 1

Saccade

Question 2

A saccade is a ___ ___ process

Answer 2

Gaze Shifting

Question 3

What are the 3 eye movements to change the angle of gaze?

Answer 3

1. Saccade
2. Pursuits
3. Vergence

Question 4

What area of the brain is for more voluntary forms of saccades?

Answer 4

Frontal Cortical

Question 5

What area of the brain is for more involuntary/reflexive forms of saccade?

Answer 5

Parietal cortical

Question 6

What higher cortical level makes the decision to make saccades?

Answer 6

Cortex

Question 7

What makes the decision to generate pulse and step?

Answer 7

Premotor neurons

Question 8

What higher cortical levels structures are involved in saccades?

Answer 8

1. Frontal Cortex
2. Parietal Cortex
3. Thalamus
4. Superior Colliculus
5. Basal Ganglia

Question 9

Lesions of the superior collicculus cause?

Answer 9

1. increased saccadic latency
2. hypometria
3. abnormal saccades
4. decreased saccadic speed
5. can’t make express saccades

Question 10

This provides the decision to generate saccades made to novel stimuli which catches one’s attention in periphery

Answer 10

Parietal Cortex

Question 11

What are the 3 premotor neurons?

Answer 11

1. Burst
2. Tonic
3. Pause

Question 12

WIT: Projects to oculomotor neurons causing a phasic contraction of EOMs to moves eyes quickly to new angle

Answer 12

Burst Neurons - sends pulse signal

Question 13

Horizontal EBN are where?

Answer 13

Paramedian Pontine Reticular Formation (PPRF)

Question 14

Horizontal IBN are where?

Answer 14

Medullary Reticular Formation (MRF) in rostral medulla

Question 15

Vertical EBN are where?

Answer 15

Rostral Interstitial Nucleus of MLF (riMLF)

Question 16

Vertical IBN are where?

Answer 16

INC and riMLF

Question 17

Unilateral lesion of the PPRF leads to deficit of saccade to the ______ side.

Answer 17

ipsilateral

Question 18

Vertical saccade palsy is caused by a lesion where?

Answer 18

riMLF

Question 19

Slow horizontal saccade is caused by a lesion where?

Answer 19

in the PPRF

Question 20

Niemann-Pick type C disease is due to an impaired _____, causing a curved trajectory

Answer 20

Vertical Saccade

Question 21

Tonic step command sends a step signal to do what?

Answer 21

hold the eye in position after the burst

Question 22

NPH and MVN as horizontal neural integrators, integrate the __ signal to a ___ signal.

Answer 22

burst signal into a step signal

Question 23

Where are the omni pause neurons located?

Answer 23

Nucleus raphe interpositus

Question 24

WIT: Pauses to allow saccade to occur; only after inhibited can burst neurons be activated to produce the pulse signal

Answer 24

Omni Pause Neurons

Question 25

When are pause neurons fired?

Answer 25

During fixation (we don't want the eye to move during this time)

Question 26

Lesions involving pause nerons lead to what?

Answer 26

1. Saccadic intrusions/inappropriate saccades

Question 27

What controls saccadic accuracy, the dynamics and initiation of saccades and saccadic adaptation?

Answer 27

Cerebellum

Question 28

What 2 things calibrate saccadic amplitude?

Answer 28

1. Dorsal Vermis 2. Fastigial Nucleus - tells how far to move the eye

Question 29

What calibrates the pulse-step match?

Answer 29

Flocculus

Question 30

What 5 things do you look for when clinically examining saccades?

Answer 30

1. Latency 2. Velocity 3. Trajectory 4. Accuracy 5. Conjugacy

Question 31

Saccades are slower if made in the darkness. What two types of saccades are the slowest?

Answer 31

1. Anti-saccades | 2. Memory guided

Question 32

Saccades of the ____ eye tend to be larger faster and more skewed than saccades of the ____ eye.

Answer 32

abducting | adducting

Question 33

Saccades usually begin within ___ msecs

Answer 33

200 msecs

Question 34

Express saccades ONLY occur in which paradigm?

Answer 34

gap paradigm | ~100msecs

Question 35

What is the speed-accuracy trade off?

Answer 35

Latency increases if accuracy is desired

Question 36

When you make a saccade, your vision is not blurred due to?

Answer 36

Saccadic Omission

Question 37

What are the 2 types of saccadic omission that prevent blurring of the vision?

Answer 37

1. Saccadic Suppression | 2. Saccadic Masking

Question 38

WIT: Reduction in visual sensitivity during eye movement

Answer 38

Saccadic suppression

Question 39

WIT: Reduction in ability to detect blur because multiple images are experienced within a short time, creating "noise".

Answer 39

Saccadic Masking

Question 40

What is the role of saccadic omission in reading?

Answer 40

Prevent blur & incoherent sentences

Question 41

Normometria = ?

Answer 41

Accurate Saccade

Question 42

Hypermetria = ?

Answer 42

Overshoot

Question 43

Hypometria = ?

Answer 43

Undershoot

Question 44

What are the non-pathologic factors that affect saccadic accuracy?

Answer 44

1. Size/Brightness of Target 2. Tiredness (glissades are found) 3. Age - usually undershoot

Question 45

WIT: Anomalies in muscular activity in which errors of accuracy or force occur

Answer 45

Saccadic Dysmetria

Question 46

What are the 3 types of saccadic dysmetria?

Answer 46

1. Static 2. Glissadic 3. Post-saccadic drift 4. Dynamic overshoot

Question 47

In hypometria, what is too small? Is this normal?

Answer 47

The step signal. | Yes. 10% is normal

Question 48

In hypermetria, what is too large? is this normal?

Answer 48

Step signal is too large. | No this is not normal

Question 49

Glissadic hypometria is caused by what? What disease is an example?

Answer 49

1. Error in the pulse signal, pulse is too small to move the eyes toward target 2. INO - adduction deficit

Question 50

Glissadic hypermetria is caused by what?

Answer 50

Error in pulse signal, pulse is too large

Question 51

WIT: Inaccuracy in saccadic generator

Answer 51

post-saccadic drift

Question 52

WIT: Reversal in central saccadic command

Answer 52

Dynamic overshoot