Higher Visual Processing

Front 1

What are the 3 parts of the visual system? What is the biggest part?

Back 1

1.optical system
2.phottransduction (rods and cones)
3.computation (*biggest part)

Front 2

How much of the brain is required for visual capacity?

Back 2

1/3

Front 3

Injury to what part of the brain causes visual disturbance/loss?

Back 3

back of th head (occipital lobe)

Front 4

What is the visual pathway?

Back 4

photons reach retina -> optic nerve -> optic chiasm -> optic tract ->lateral geniculate nucleus of thalamus (LGN) -> optic radiation to primary visual cortex

Front 5

How do humans visual abilities differ from a camera?

Back 5

we can record and perceive

Front 6

What are the major targets of retinal ganglion cells?

Back 6

retinal recipient nuclei (i.e. LGN)

Front 7

What are retinal recipient nuclei?

Back 7

groups of neurons that get direct input from retina

Front 8

Where do 90% of retinal ganglion cells terminate? What is this system responsible for?

Back 8

in LGN;
conscious vision

Front 9

Where do the remaining retinal ganglion cells terminate?

Back 9

Superior colliculus (5-7%)
Suprachiasmatic Nucleus
Pretectum
Accessory optic system

Front 10

What is the suprachiasmatic nucleus mainly responsible for?

Back 10

circadian rhythm regulation

Front 11

What is the pretectum mainly responsible for?

Back 11

pupillary light reflex

Front 12

What is the accessory optic system mainly responsible for?

Back 12

stablilizing one's gaze

Front 13

What are saccades? What are they moderated by?

Back 13

rapid pointing eye movements;
the superior collicululs

Front 14

*Explain the pupillary light reflex circuit.

Back 14

photons reach retina ->
optic nerve -> optic chiasm ->
pretectal olivary nucleus sends fibers to BOTH Edinger-whestphal nuclei ->
CN III ->
Ciliary ganglion ->
Ciliary nerves ->
iris constrictor muscles

Front 15

Out of the nearly one million ganglion cells how many take the route on each side for the pupillary light reflex?

Back 15

a few thousand

Front 16

What will lesions to the following areas result in:
1. LGN -> cortex pathway
2. cortical lesion
3. retina -> LGN -> primary visual cortex
4. lesions in cortex other than primary visual cortex

Back 16

1. comeplete blindness (loss of conscious vision, can still have some reflexes, eg. pupillary)
2. can act on visual info but don't have conscious awareness of it
3. specific visual field defects
4. subtle visual defects

Front 17

What is blindsight?

Back 17

involves a very limited ability to perform visually guided tasks when there is destruction along the visual tract; the apparent absence of conscious perception

Front 18

What do lesions to the extrastiate visual cortex cause?

Back 18

more subtle defects in a person's ability to comprehend what they are looking at, but with normal visual fields and acuity

Front 19

What is the LGN a part of?

Back 19

thalamus

Front 20

What is oculus sinistra and oculus dextra?

Back 20

O.S. = left eye
O.D. = right eye

Front 21

T/F: Fibers from each eye terminate on occiptial cortex bilaterally.

Back 21

true

Front 22

Which fibers coming from the retina cross at the optic chiasm?

Back 22

medial fibers

Front 23

What does injury to the right optic nerve reuslt in?

Back 23

right eye blindess

Front 24

What does a lesion at the optic chiasm lead to?
What is this?

Back 24

bitemporal hemianopia;
lateral (peripheral) half of vision in each eye is knocked out

Front 25

What does a lesion to the right optic tract cause? What is this?

Back 25

Left homonymous hemianopia;
left half of visual field is knocked out in both eyes

Front 26

What does a lesion to the right Meyer's loop (in cortex) result in? What is this?

Back 26

Left Superior Quadrantanopia;
superior lateral quadrant is knocked out equally in both eyes

Front 27

What are some synonymous names for the primary visual cortex?

Back 27

striate cortex, area 17, area V1

Front 28

What might cause lesions in the visual pathway?

Back 28

pituitary tumors

Front 29

What are the right and left monocular crescents attributed to?
Which eye can see a little further?

Back 29

the nose getting in the way of vision;
the right eye

Front 30

Most of our visual field is (binocular/monocular).

Back 30

binocular

Front 31

Where does the initial inversion in the visual field happen? Where is it made right-side-up?

Back 31

retina;
cortex

Front 32

What is the most expensive effort in vision?

Back 32

analyzing and computing the image in the brain

Front 33

We have a lot more detail in the ______ than we do in the ______.

Back 33

fovea;
periphery

Front 34

Which area requires a lot more cicuitry than other areas to interpret its input?

Back 34

the fovea

Front 35

T/F: Points that are near each other on the retina will not necessarily be near each other in the cortex.

Back 35

F, they will be near each other in the cortex too

Front 36

What is the cortical magnification factor?

Back 36

the area of the fovea is larger than the rest (relative sizes and orders have been distorted)

Front 37

where does the greatest amount of visual work occur?

Back 37

0 degrees

Front 38

1.What are M cells? P cells?
2.Sensitive to color contrast?
3.Sensitive to low contrast stimuli?
4.Sensitive to temporal frequency?
5.Sensitive to spatial frequency?
6.Respond to quickly moving stimuli?
7.See (broad/fine) detail?

Back 38

1.Magno (large) and Parvo (small) ganglion cells that leave retina in a parallel pathway
2.M=no, P=yes
3.M=yes, P=no
4.M=yes, P=no
5.M=no, P=yes
6.M=yes, P=no
7.M=broad, P=fine

Front 39

Explain M cells.

Back 39

Magno ganglion that leave the retina in parallel pathways
not sensitive to color contrast
sensitive to low contrast stimuli & temporal frequency
low sensitivity to spatial frequency (don't see fine detail)
respond to quickly moving objects

Front 40

Explain P cells.

Back 40

Parvo (midget) ganglion cells that leave retina in a parallel pathway
high sensitivity to spatial frequency (see fine detail)
see color
not sensitive to temporal frequency (don't respond to quickly moving stimuli)

Front 41

How do magno and parvo ganglion cells leave the retina?

Back 41

in a parallel pathway

Front 42

T/F: Multiple systems and regions of the brain are needed to analyze an image.

Back 42

True

Front 43

Where does the division of labor in vision occur?

Back 43

the retinal ganglion cells

Front 44

Do M and P cells cross in the chiasm?

Back 44

no

Front 45

Which fibers from the 6 layers of the LGN cross?

Back 45

1,4,6

Front 46

What is the mnemonic to remember which fibers cross in the LGN?

Back 46

1,4,6 cross the river Styx
2,3,5 stay on the same side

Front 47

Which layers of the LGN are M-cell layers? Which are P cell layers?

Back 47

2 most ventral (1,2) are M cell
4 most dorsal (3-6) are P cell

Front 48

Is there binocular computation between M and P cell layers bilaterally?

Back 48

no

Front 49

What are R cells? What synapses on R cells?

Back 49

Relay cells in the LGN that relay info from the retina to the visual cortex;
interneurons (most are not directly from retina)

Front 50

What does LGN receive inputs from?

Back 50

brainstem, visual cortex, retina, and perigeniculate nucleus (PGN)

Front 51

Are there more interneurons or relay neurons in the LGN?

Back 51

interneurons

Front 52

Where is most of the primary visual cortex in humans? where is the fovea? where is the periphery?

Back 52

in the calacrine sulcus;
near the surface;
deeper

Front 53

What is the striate cortex?

Back 53

heavy band of myelinated axons in layer 4, the stria of Gennari, about the only landmark you can see in the cortex without special stains
(synonym for the primary visual cortex)

Front 54

What is the pathway from LGN to Area V1 called?

Back 54

Thalamocortical or Geniculostriate pathway

Front 55

What layer is the basic input area in the LGN?

Back 55

layer 4

Front 56

T/F: Retinal ganglion cells and LGN cells have radically symmetric fields.

Back 56

True

Front 57

T/F: You see no changes from LGN -> Area V1.

Back 57

False, because V1 is very different from retina and LGN

Front 58

What does V1 deal with with respect to images?

Back 58

the orientation of the image

Front 59

What do the ganglion cells of retina and LGN differentiate between?

Back 59

on vs. off-center and on-surround vs. off-surround (not concerned with orientation of images)

Front 60

What are the 2 basic types of cells in V1?

Back 60

V1 simple cells & V1 complex cells

Front 61

Describe V1 simple cells:
What are they like?
What is their optimal stimulus?
What are they selective for

Back 61

-like on-surround/off-surround cells in retina; have discrete excitatory and inhibitory subregions
-a vertical/angled strip of light flanked by darkness
-orientation

Front 62

Describe V1 complex cells:
Inhibitory/excitatory regions?
What are they selective for?
What are they concerned about?

Back 62

-don't have inhib & excite regions
-orientation regardless of small shifts in position or changes in contrast
-only orientation

Front 63

How would complex V1 cells note a change in an image?

Back 63

only if there is a change in orientation

Front 64

Which type of V1 cells are more precise in their detection of location of stimuli?

Back 64

simple cells

Front 65

What regions are obligatory for vision? What do the other regions do?

Back 65

retina, LGN, V1;
allow us to see well (V2)

Front 66

Is the striate or extrastriate visual cortex larger?

Back 66

extrastriate

Front 67

What is the Dorsal Stream? What cells does it involve and what do they tell us?

Back 67

V1 -> V2 -> Posterior Parietal Cortex;
Magno cells;
where an object is in space

Front 68

What is the Ventral Stream? What cells does it mainly involve and what do they tell us?

Back 68

V1 -> V4 -> Inferior Temporal Cortex;
Parvo cells;
"what" we are seeing

Front 69

What happens if you lesion the posterior parietal lobe in a primate?

Back 69

it will have trouble with landmark discrimination in relation to other objects

Front 70

What will happen if you lesion the inferior temporal cortex in a primate?

Back 70

it will have trouble telling the different shapes apart

Front 71

What kind of cells in V2? What is V2 closely associated with?
Is it ventral or dorsal?
What are its neurons similar to?
Size of recpetive fields?

Back 71

M and P cells
V1
neither ventral nor dorsal
V1 neurons
small receptive fields

Front 72

What is V4?
What does it deal with?

Back 72

more ventral stream;
complex color and form/shape (spirals) properties

Front 73

Describe IT (Inferior Temporal Cortex):
Where?
What is it important for?
Size of receptive fields?
type of cells?

Back 73

ventral (last heirarchy of ventral stream)
distinguishing b/w 2 faces
large (~30 degrees)

Front 74

What is prsopagnosia?

Back 74

loss of the ability to recognize faces with no corresponding loss of acuity or visual field deficits

Front 75

What is the Middle temporal cortex(MT)/V5 involved in?
What is it a part of?

Back 75

motion and perception of motion;
a small but significant part of dorsal stream