Topic 9 -Eye Movements

Question 1

Saccade

Answer 1

Fast discrete eye movements that move an object to the FOVEA

Pulse-step pattern

Question 2

Pursuit

Answer 2

Slow smooth eye movements that maintain an object to the fovea
(Cursor on a computer screen)

Only occur when you’re tracking something in space

Question 3

Occulomotor nucleus

Answer 3

Adduction of eye

Question 4

Abducens nucleus

Answer 4

Abduction of eye

Question 5

Paramedian pontine reticular formation (PPRF)

Answer 5

In pons

Responsible for horizontal movements of eye

Question 6

Conjugate movement

Answer 6

Eyes move in same direction

Question 7

Vergence movement

Answer 7

Eyes move in opposite directions

Question 8

Omnipause neutron

Answer 8

Provides inhibitory signals to the burst neuron (to keep eyes still)

So when we want eye movement we have to inhibit the omnipause neuron

Question 9

Burst neuron

Answer 9

Fire at high frequency just before and during saccade

Give ridge to “pulse”/movement component

Firing rate is proportional to saccade velocity

Question 10

Tonic neuron

Answer 10

Firing rate increases or decreases linearly in relation to horizontal position of eye (gives indication of horizontal location of eye)
- if you look in one position it may lower activation but if you look at another position it may increase activation

Gives rise to “step”/stable component

Question 11

Burst-tonic neurons

Answer 11

Firing pattern reflects both “pulse” and “step” components

Raptors plot is combination of burst and tonic neurons

Question 12

Omnipause neurons (aka fixation neurons)

Answer 12

Fire at all times except immediately prior to or during the saccade (so whenever eye is not moving or not about to move)

Keeps eye stable

Inhibits burst neurons when movement isn’t wanted

Question 13

What kinds of neurons does the superior follicules have

Answer 13

Visual neurons

Movement-related neurons

Fixation neurons

Question 14

Fixation neurons

Answer 14

Provide excitatory input to Omnipause neurons allowing us to keep our eyes on somethint

Question 15

Visual grasp effect

Answer 15

Efficient transformation of visual info to motor command/program

Question 16

What influences RT in the visual grasp effect?

Answer 16

Fixation neurons & movement related neurons

Higher level of pre stimulus activity = lower RT

Question 17

Where does inhibition of pre-target movement-related neuron activity occur in the brain

Answer 17

Dorsolateral PRE FRONTAL cortex

Question 18

Where does movement vector inversion happen?

Answer 18

LIP lateral intraparietal area of PPC

Question 19

What needs to happen for an antisaccade?

Answer 19

1. Response suppression of pro-saccade

2. Movement vector inversion