Chapter 6 visual system

Question 1

___ is also known as the blind spot

Answer 1

Retina - everyone has a spot in their retina where the optic nerve connects. In this area there are no light-sensitive cells so this part of your retina can’t see. We call this the blind spot.

Question 2

where does axons of the receptors leave the eye and form the optic nerve,?

Answer 2

Optic disk:

Question 3

We are blind to any objects
whose image falls on which part of the retina?

Answer 3

Optic disk? why - no photoreceptors - The CNS fills it in.

Question 4

What is a fovea specialized for ?

Answer 4

• The fovea is specialized for high acuity, color vision in bright light -

Question 5

where is fovea located?

Answer 5

A yellowish circular area near optic disk is macula and the center is
fovea

Question 6

True or false - The center of the fovea contains only rods.

Answer 6

False - cones

Question 7

Which area is good for vision in lower light?

Answer 7

coutside the macula. - coz the * The rod density reaches maximum

Question 8

there are ___ type of neuronal cell

Answer 8

5

Question 9

The axons of ganglion cells leave the eye as?

Answer 9

Optic nerve

Question 10

What is the direction of Neruonal communication and direction of light ?

Answer 10

neuronal - photo - bipolar - ganglion , opposide for dol

Question 11

Rods only respond to up to?

Answer 11

moonlight level of light intensity

Question 12

True or false Spatial resolution in dim light is poor.

Answer 12

True

Question 13

Rods respond faster than cones. True or false

Answer 13

False

Question 14

cones are more sensitive than rods true or false?

Answer 14

false - Cones are less sensitive. They require moonlight or greater levels of
illumination to function

Question 15

mix & match cones for color vision Long-wavelength cones, , Middle-wavelength cones, . Short-wavelength cones,

Answer 15

red,green, blue

Question 15

What causes receptor potentials in rods and cons

Answer 15

• Photons are absorbe

Question 16

What causes receptor potentials in rods and cons

Answer 16

• Photons are absorbed

Question 17

why is there constant appearance of objects despite varying illumination?

Answer 17

This is because the visual system is attuned to the detection of borders, between light and dark areas, or areas b/w diff colours.

Question 18

true or false * Neurons at each level of the visual system has a RF.

Answer 18

True

Question 19

What is the primary visual cortex,
around the calcarine sulcus also called?

Answer 19

striate cortex

Question 20

__ contributes to guided eye movements

Answer 20

superior colliculus

Question 21

what is LGN and where is it located WHat happpends to optic fibres/ nerves her

Answer 21

lateral geniculate neucleus, thalamus located. they stop

Question 22

• LGN neurons do not reach adult size until ___ years.

Answer 22

2

Question 23

Only ___ 10 % of inputs to LGN come from the
, ___ from cortex of the brain

Answer 23

retina, 90%

Question 24

how many layers does LGN have ?

Answer 24

6

Question 25

Retinotopic mapping at V1

Question 26

What are layers 1-2 , 3-6 called?

Answer 26

parvocellular and magnocellular

Question 27

what is functions of parvocellular?

Answer 27

Orientation discrimination in very young infants * Color discrimination in 4 week olds

Question 28

Magnocellular functions develop later, which are?

Answer 28

Direction selective responding to motion in 6 to 8 week olds * Depth processing in 3 to 4-month-old

Question 29

True or false - Orientation columns: Neurons located above and below one another in the same column have different properties.

Answer 29

False - Orientation columns: Neurons located above and below one another in the same column have similar properties.

Question 30

What are color blobs?

Answer 30

They are dark regions in the left image - * Color sensitive * In layer II and III in V1

Question 31

where- superior longitudinal fascilusMix and match 1. * Orientation columns, 2. * Color blobs 3. * Ocular dominance columns 1. * receive input from one eye- Depth perception 2. * Sensitive to color 3.discriminatory on spatial orientation

Answer 31

1-3, 2-2 3,1

Question 32

Which brain structures are associated with where and what pathways?

Answer 32

superior longitudinal fasciculus and posterior parietal cortex. What - inferior longitudinal fasciculus , inferior temporal cortex

Question 33

what pathway fucntion?

Answer 33

– Tracking moving objects, relative motion information

Question 34

What pathways?

Answer 34

– Hierarchical representation as proceed more anterior: feature to object

Question 35

What is the route of the where pathway?

Answer 35

dorsal pathway to V5/MT then to posterior parietal cortex

Question 36

what is the route of what pathway?

Answer 36

ventral pathway , through v4 to inferior temporal cortex

Question 37

* fMRI reveals double dissociation between the two pathways true or fale?

Answer 37

true