Lecture 7 T1 Vision2

Question 1

What are the layers of the retina?

Answer 1

Photoreceptors, horizontal cells, bipolar cells, amacrine cells, ganglion cells

Question 2

Rods and cone cells stimulate bipolar cells due to what neurotransmitter?

Answer 2

Glutamate

Question 3

What do amacrine cells of the retina release?

Answer 3

8 or more kinds of neurotransmitters (GABA, glycine, dopamine, ACh, indolamine (all inhibitory)).

Question 4

Horizontal cells can be seen as ________, being the interaction between several different cells.

Answer 4

interneurons

Question 5

Photoreceptors include what structures?

Answer 5

Rods and cones

Question 6

Where do photoreceptors transmit signal?

Answer 6

the outer plexiform layer

Question 7

What structure synapses with bipolar cells and horizontal cells?

Answer 7

Photoreceptors

Question 8

Where do horizontal cells transmit signals?

Answer 8

from rods and cones to bipolar cells, and transmit signals to outer plexiform layers

Question 9

True/False: Horizontal cells output is always excitatory.

Answer 9

False. Horizontal cells output is always inhibitory

Question 10

What do bipolar cells synapse with?

Answer 10

amacrine and ganglion cells

Question 11

Where do bipolar cells transmit signals?

Answer 11

from rods, cones, and horizontal cells

to inner plexiform layer

Question 12

Where do amacrine cells transmit signals?

Answer 12

Directly from bipolar to ganglion cells
OR
Within inner plexiform layer from axons of bipolar cells to dendrites of ganglion cells or to another amacrine cell

Question 13

Where do ganglion cells transmit signals?

Answer 13

ganglion cells transmit signals from retina to the brain.

Question 14

Axons of what cells make up the optic nerve?

Answer 14

Ganglion cells

Question 15

What are the only retina cells that transmit action potentials?

Answer 15

axons of the ganglion cells.

Question 16

Where do interplexiform cells transmit signals?

Answer 16

They transmit signals from the inner plexiform later to the outer plexiform layer

Question 17

What type of signals do interplexiform cells give and for what function?

Answer 17

Inhibitory signals; lateral inhibition

Question 18

What are the four neurons that make up pure rod vision?

Answer 18

Rods, bipolar cells, amacrine cells, and ganglion

Question 19

What is the function of most amacrine cells?

Answer 19

interneurons that help analyze visual signals before they leave the retina

Question 20

Approaching the fovea, fewer rods and cones converge on each optic fiber and rods and cones become more slender. This increases ________________ in central retina.

Answer 20

visual acuity

Question 21

In the central fovea there are only slender cones and no rods. This means that this is an area of ________.

Answer 21

pure color vision

Question 22

The ________ is more sensitive to weak light.

This also means there is ______ visual acuity.

Answer 22

peripheral retina; less

Question 23

What percentage of ganglion cells are made up by W ganglion cells?

Answer 23

40%

Question 24

What size are W ganglion cells?

Answer 24

small

Question 25

What type of ganglion cells are most likely responsible for all color vision?

Answer 25

X ganglion cells

Question 26

Which type of ganglion cells transmit signals the fastest?

Answer 26

Y ganglion cells.

Question 27

What receives input from the optic nerve?

Answer 27

dorsal lateral geniculate nucleus

Question 28

What is the function of the DLGN?

Answer 28

relays information from the optic tract to visual cortex by was of optic radiation (geniculocalcarine tract), which confers a high degree of spatial fidelity from retina to the visual cortex.

Question 29

How many layers in the geniculate nucleus?

Answer 29

6
2,3,5 - receive signals from lateral half of ipsilateral retina
1,4,6 - receive signals from medial half of opposite retina

Question 30

What is the approximate decussation of the DLGN?

Answer 30

about 50% in optic chiasm

Question 31

True/False: lateral geniculate body receives information from both eyes.

Answer 31

True

Question 32

What are layers 1 and 2 of the geniculate nucleus known for?

Answer 32

magnocellular layers (magnocellular = big cells, named for histological appearance of cells), contain large neurons, provide rapidly conducting pathway to visual cortex, receives input almost entirely from the large Y type ganglion cells, transmit only back and white, and point to point transmission is poor.

Question 33

What type of matter are the layer are in the geniculate nucleus?

Answer 33

gray matter

Question 34

What are layers 3-6 of the geniculate nucleus known for?

Answer 34

parvocellular layers, small to medium neurons, receives input from type X ganglion cells, provides moderate conducting pathway to visual cortex, transmits color and provides accurate point to point transmission.

Question 35

Type X ganglion cells

Answer 35

color vision, sharpest vision, medium speed of transmission

Question 36

What is the location of the primary visual cortex?

Answer 36

Occipital lobes

Question 37

What signals does the primary cortex receive?

Answer 37

• signals from the macular area terminate near the occipital lobe
• signals from the more peripheral retina terminate at or in concentric half circles ant to the pole bit still along the calcarine fissure.

Question 38

How many layers of the primary cortex?

Answer 38

6 layers

Question 39

In the primary cortex, what later do the geniculocalcarine fibers terminate?

Answer 39

4

Question 40

Special column-like areas called ______________ are located among the columns of the secondary visual areas. They receive later signals from adjacent visual columns and are activated specifically by color signals.

Answer 40

color blobs

Question 41

In what layer of the primary visual cortex do signals from the two separate eyes ender alternating stripes of columns?

Answer 41

Layer IV

Question 42

What deciphers whether the respective areas of the two visual images from the two separate eyes are in register with each other? What is this deciphered information used to do?

Answer 42

Cortical area; adjust the directional gaze of the separated eyes.