Vision part 2

Question 1

blindsight

Answer 1

the paradoxical presence of visual abilities in the absence of the visual cortex

Question 2

the patient claims to be blind but respond to visual stimuli they don’t consciously see

Answer 2

blindsight

Question 3

people can guide hand movements toward an object even though they can’t see what they’re reaching for

Answer 3

blindsight

Question 4

How is blindsight mediated?

Answer 4

by mechanisms in the superior colliculus that continue to get input from the retina.

Question 5

People can unconsciously read emotion and mimic it without seeing it happen

Answer 5

blindsight

Question 6

people can move around obstacles without seeing them

Answer 6

blindsight

Question 7

the primary visual cortex

Answer 7

• V 1
• aka striate cortex
• first place in the cortex to receive visual information
• 6 layered structure
• bilateral (left and right side)

Question 8

layer 4

Answer 8

• in V1
• the critical layer that receives information from the LGN
• all synapses of LGN happen here

Question 9

what is something that the LGN, superior colliculus, and V1 all have in common?

Answer 9

the V1 has a retinotopic map of the retina

Question 10

cortical magnification

Answer 10

• some areas of the retina take up more space on V1 than others
• the fovea is 1% of the retina but is represented on over 50% of the V1

Question 11

what does the fovea represent?

Answer 11

it represents the place where the left and right V1s meet in the middle of the brain

Question 12

V4

Answer 12

• orientation, spatial frequency, and color

- some V4 cells produce strong responses to concentric, radial, or color stimuli

Question 13

fusiform face area

Answer 13

• FFA
• faces and other objects that require expertise
• in temporal lobe

Question 14

prosopagnosia

Answer 14

• inability to recognize faces
• damage to FFA
• face blindness

Question 15

where is the superior colliculi located?

Answer 15

at the top of the brainstem, just beneath the thalamus on each side

Question 16

what does the superior colliculus receive?

Answer 16

• light information from the contralateral retina

- also input from other sensory systems (allows us to orient the direction of a sound or touch)

Question 17

what is the main function of the superior colliculus?

Answer 17

control of rapid eye movement

Question 18

what is the superior colliculus necessary for?

Answer 18

smooth pursuit and saccades

Question 19

saccades

Answer 19

fast movements when you’re looking at one object to the next

Question 20

approximately ____ of ___ ganglion cells synapse in the _____, but the other ____ go to the _____

Answer 20

90%
retinal
LGN
10%
superior colliculus

Question 21

simple cortical cells

Answer 21

• in V1
• detect edges/bars in specific size and orientations
• help us determine the shape of objects in visual field

Question 22

complex cortical cells

Answer 22

• in V1

- respond best to a bar of a particular width and orientation that is in motion anywhere in the visual field

Question 23

Lateral Geniculate Nucleus

Answer 23

• LGN
• relays visual information from the optic nerve to the visual cortex
• 6 layers

Question 24

magnocellular cells

Answer 24

• in LGN
• form movement, depth, and brightness
• each layer receives info from only one eye

Question 25

parvocellular layers

Answer 25

- in LGN - color - fine details - each layer receives info from only one eye

Question 26

koniocellular layers

Answer 26

- in LGN - blue color - each layer receives info from only one eye

Question 27

V2

Answer 27

- adjacent/wraps around V1 | - detects textures (in visual environment), patterns, and illusory boundaries

Question 28

Dorsal stream

Answer 28

- assesses the location of objects - guides out movement towards objects - "where"

Question 29

where is the dorsal stream located

Answer 29

parietal lobe

Question 30

what are the 2 main processing streams that originate in the primary visual cortex and pass through the secondary cortex?

Answer 30

dorsal and ventral stream

Question 31

optix ataxia

Answer 31

- damage to dorsal stream | - difficulty using vision to reach for and grasp objects

Question 32

ventral stream

Answer 32

- identifying objects | - "what"

Question 33

where is the ventral stream located

Answer 33

temporal lobe

Question 34

what is the main input for ventral stream

Answer 34

main input from parvocellular layer of LGN and fovea

Question 35

where does the parvocellular layer receive most of its information from?

Answer 35

cones

Question 36

what does damage to the ventral stream cause?

Answer 36

problems in perceiving faces and objects

Question 37

where does the dorsal stream get its information from?

Answer 37

- visual input from across the retina

Question 38

what happens once information leaves the second visual area?

Answer 38

- information is split up into the dorsal and ventral streams

Question 39

where is the LGN located?

Answer 39

in the thalamus

Question 40

what does each neuron in each layer of the LGN show?

Answer 40

retinotopic organization

Question 41

what other cortical layers are involved in the perception of form?

Answer 41

V2, V4, and the inferior temporal lobe

Question 42

V5

Answer 42

- aka media temporal area (MT) | - specialized for motion perception

Question 43

what does the V1 perceive? what is it necessary for?

Answer 43

- perceives objects and events | - necessary in forming mental images

Question 44

where is the parahippocampal place area located?

Answer 44

in the temporal lobe

Question 45

When does the PPA activate?

Answer 45

when you see scenes and backgrounds

Question 46

what does the PPA contribute to forming?

Answer 46

the context of visual scenes