Lecture 23 - Visual Feedback to Control Voluntary Motor-Actions

Question 1

What is the dorsal visual stream important for?

Answer 1

Controlling actions

Question 2

What is the ventral visual stream important for?

Answer 2

perceptual judgements

Question 3

What is exteroception?

Answer 3

Sensory information that tells us about the state of our body in relation to the world around us

Question 4

What is the most dominant source of exteroceptive feedback for motor control?

Answer 4

visual information

Question 5

What are the 2 photoreceptors in human eyes?

Answer 5

Rod and cones

Question 6

Are there more rods or cones?

Answer 6

rods (90-120 million)

cones have about 4.5 million

Question 7

Where are rods concentrated?

Answer 7

peripheral portions of the retina

Question 8

Where are cones concentrated?

Answer 8

central portion of retina (fovea)

Question 9

Which photoreceptors have high spatial resolution (visual acuity) and specialize in colour vision?

Answer 9

cones

Question 10

Where does the specialization of visual pathways for perceptial judgments and online control of actions begin?

Answer 10

The retina

Question 11

What happens to rods and cones when they interact with light?

Answer 11

They hyperpolarize

Question 12

What are rods senstive to?

Answer 12

Motion

Question 13

Do rods or cones have multiple cells attached to one ganglion?

Answer 13

Rods

Question 14

What is the dorsal stream know as?

Answer 14

the ‘where’ pathway

Question 15

What is the ventral stream know has?

Answer 15

The ‘what’ pathway

Question 16

What does the dorsal stream use vision for?

Answer 16

Action guidance

Question 17

What does the ventral stream use vision for?

Answer 17

perception (ie. orientation)

Question 18

What is the ventral-dorsal stream for?

Group with dorsal stream

Answer 18

visuomotor transformations for grasping and important for interpreting the actions of others

Question 19

Which stream is used for object identification and recognition (perception)?

Answer 19

ventral stream

Question 20

What is form agnosia?

Answer 20

Ventral stream damage
can cause selective impairments in conscious object perception but intact control of actions

Question 21

Is the ventral or dorsal stream unconscious visual processing?

Answer 21

dorsal

Question 22

Is dorsal or ventral stream slow processing of visual information?

Answer 22

ventral

Question 23

Which stream does visual feedback processing occur, and is used to correct ongoing actions?

Answer 23

Dorsal

Question 24

What is damage to the dorsal stream called? What does it cause?

Answer 24

Optic ataxia

selective impairments in the inabiklity to use vision to guide reaching movements (cannot orient hand properly to fit in a slot

Question 25

What could cause optic ataxia?

Answer 25

Stroke or physical trauma

Question 26

What is optic flow?

Answer 26

Light moving across the retina

Question 27

optic flow

What occurs when the object is closer to the eye?

Answer 27

Size of the image on the retina changes at a faster rate

Question 28

What informnation is provided by optic flow?

Answer 28

• time to contact
• direction of movement relative to objects in environment
• movement of objects in the environment
• stability and balance
• velocity of movement rhough the environment

Question 29

Optic flow

Rate of expansions increases as time to contact _____?

Answer 29

decreases

Question 30

Does vision help improve the accuracy of slow, deliberate movements or fast movments?

Answer 30

Slow deliberate movements (light less useful for faster movements)