Exam 2 Material: Vision Pt. 2

Question 1

2 parts of the retina

Answer 1

nasal retina and the temporal retina

Question 2

left visual field strikes what side of the brain?

Answer 2

right side

Question 3

ganglion cells conduct action potentials along axons that make up the

Answer 3

optic nerve

Question 4

where do the optic nerves of each eye meet

Answer 4

optic chiasm

Question 5

what happens at the optic chiasm

Answer 5

each optic nerve splits in half

Question 6

Where does information from the left visual field strike in terms of the nasal retina and the temporal retina

Answer 6

strikes the left nasal and the right temporal retina

Question 7

axons from the right half of each retina combine forming the right optic tract which goes on to which hemisphere?

Answer 7

right

Question 8

where do most optic tract axons synapse

Answer 8

lateral geniculate nucleus (LGN) in the thalamus

Question 9

What brain regions does the LGN project to?

Answer 9

hypothalamus: circadian rhythms
tectum: eye movements/eye muscles

Question 10

What do axons of the postsynaptic cells of the LGN form?

Answer 10

optic radiations

Question 11

Where do optic radiations terminate?

Answer 11

primary visual cortex (V1) of the occipital lobe

Question 12

LGN

Answer 12

relays visual info from the optic nerve to the visual cortex

Question 13

Layers of the LGN

Answer 13

6
magnocellular layers
parvocellular layers
koniocellular layers

Question 14

magnocellular layers of LGN

Answer 14

1 & 2

form, movement, depth, brightness

Question 15

parvocellular layers of LGN

Answer 15

3 & 4 & 5 & 6

color and fine details

Question 16

koniocellular layers

Answer 16

in between the magnocellular and parvocellular layers

white bands

Question 17

neurons in each layer of the LGN show

Answer 17

retinotopic organization

Question 18

Where is the superior colliculi?

Answer 18

at the top of the brainstem, just beneath the thalamus on each side
- receives light from contralateral retina

Question 19

90% retinal ganglion cells synapse ______ and 10% go to _______

Answer 19

in the LGN

superior colliculi

Question 20

What is the main function of the superior colliculus

Answer 20

control of rapid eye movements (cicadic)

• necessary for smooth pursuit and saccades
• it also integrates info

Question 21

blindsight

Answer 21

paradoxical presence of visual abilities in the absence of the visual cortex
- patient claims to be blind but respond to stimuli they cannot consciously see

Question 22

People with blindsight can…

Answer 22

guide hand movements to an object even though they cannot see what they are looking for
sense emotion!!! on peoples faces and mimic those faces

Question 23

What is blindsight mediated by?

Answer 23

mechanisms in the superior colliculi that get info from retina

Question 24

first place in the cortex to receive visual info

Answer 24

V1 (primary visual cortex)

Question 25

V1

Answer 25

6 layers responds to simple visual components like orientation and direction - looks like stripes (aka striate cortex) - bilateral

Question 26

V1 layer 4

Answer 26

critical layer that receives info from the LGN

Question 27

The left and right V1s meet in the middle of the brain in an area that represents the...

Answer 27

fovea

Question 28

cortical magnification

Answer 28

some areas of the retina take up more space on V1 than others fovea on over 50% of V1

Question 29

with a high acuity you have lots of cones in the fovea so you have ________responsible for detecting light

Answer 29

many separate neurons

Question 30

In the V1 how do the cells line up?

Answer 30

in columns sensitive to the orientation of objects in particular areas in the visual field

Question 31

2 types of cells in the receptive fields of V1 cells

Answer 31

simple cells and complex cells

Question 32

simple cells in V1 receptive field

Answer 32

detect edges/bars in specific orientations or locations in the visual field help determine the shape of the objects many lines (action potentials) means cell responds strongly sensitive to orientation

Question 33

complex cells in V1 receptive field

Answer 33

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

Question 34

What other cortical structures are involved in the perception of form?

Answer 34

V2, V4, and the inferior temporal lobe

Question 35

What is V5 specialized for

Answer 35

motion perception | it is aka medial temporal area (MT)

Question 36

What does V2 detect?

Answer 36

texture (looking at sandpaper and knowing it will be rough), patterns, and illusory boundaries

Question 37

What happens to information that leaves the second visual area?

Answer 37

it gets split into the dorsal and ventral streams

Question 38

illusory contours

Answer 38

perception of edge without an actual edge being drawn

Question 39

What is V4 important for?

Answer 39

orientation, spatial frequency, and color | some produce strong responses to concentric, radial, or color stimuli

Question 40

What are the two main processing streams that originate in the primary visual cortex?

Answer 40

dorsal stream and ventral stream

Question 41

Dorsal stream

Answer 41

"where" | assessing locations of objects and guiding our movements toward them

Question 42

where is the dorsal stream?

Answer 42

parietal lobe visual input from across the retina most rods

Question 43

what if you damage your dorsal stream?

Answer 43

optic ataxia

Question 44

optic ataxia

Answer 44

difficulty using vision to reach for and grasp objects | - hard to predict where things will be in visual field

Question 45

ventral stream

Answer 45

"what" | identifying objects

Question 46

Where is main input from for the ventral stream?

Answer 46

parvocellular layer or LGN and the fovea | most cones

Question 47

What can damage to the ventral stream cause?

Answer 47

problems in perceiving faces and objects | what am i looking at

Question 48

3 "what" pathway brain regions

Answer 48

fusiform face area (FFA) medial temporal lobes parahippocampal place area (PPA)

Question 49

fusiform face area

Answer 49

faces and other objects that require expertise

Question 50

what is the inability to recognize faces? | when you see a face it will not look like a face, blurry

Answer 50

prospagnosia

Question 51

medial temporal lobes

Answer 51

specifically identify visual features in field - if binge watch TV show you will have cells for things you see repeatedly - specific neurons firing for them, more action potentials for jennifer aniston from friends

Question 52

Parahippocampal place area (PPA)

Answer 52

in temporal lobe scenes and backgrounds - this area is activated when looking at environmental scenes