Vision Retina 2

Question 1

major difference between rods vs cones? (what type of vision?)

Answer 1

• rods: scotopic vision (dim light)
• cones: photopic vision (bright light) + colour

Question 2

scotopic vision vs photopic vision

Answer 2

• scotopic vision = dim light
• photopic vision = bright light

Question 3

TRUE or FALSE: only rods are found at the fovea and lots of cones are in the periphery

Answer 3

FALSE: only cones are found at the fovea and lots of rods are in the perpiphery

Question 4

TRUE or FALSE: there are no photoreceptors in the blindspot

Answer 4

TRUE

Question 5

TRUE or FALSE: there is more convergence from rods than from cones

Answer 5

TRUE

Question 6

what is the average convergence for rods and cones?

Answer 6

rods = 120:1
cones = 6:1

(ganglion cell:photoreceptor)

Question 7

What is convergence for rods and cones?

Answer 7

ratio of ganglion cells synapsing on photoreceptors (Ganglion cell:photoreceptors)

Question 8

How many types of cones are found in placental mammals? what are the types? what are the wavelengths?

Answer 8

• 3 cones
• S cone = blue cone (420 nm)
• M cone = green cone (534 nm)
• L cone = red cone (564 nm)

hint: BS-GM-LR….small-medium-large

Question 9

Which cone is the most sensitive? How much more sensitive is it?

Answer 9

L-cone (3x more sensitive than the others)

Question 10

TRUE or FALSE: there are more S cones than other types of cones

Answer 10

FALSE: there are more L cones

Question 11

protanopia vs deuteranopia vs tritanopia (which cone are you missin? which colours do you see/ where is the neutral point?)

Answer 11

• protanopia: missing L-cone; see blue and yellow; blind to red and green; low neutral point
• deuteranopia: missing M-cone; see blue and yellow; red and green; low neutral point
• tritanopia: missing S-cone; see blue and red; high neutral point

Question 12

Which type of colour blindness is the most rare?

Answer 12

tritanopia

Question 13

What is s-cone monochromacy?

Answer 13

missing M-cone and L-cone

Question 14

What is rod monochromacy?

Answer 14

missing all cones

Question 15

TRUE or FALSE: true colour blindness is tritanopia

Answer 15

FALSE: true colour blindness is rod monochromacy

Question 16

Which cone are both M cone and L cone variants of?

Answer 16

LWS cone

Question 17

TRUE or FALSE: the distribution of photoreceptors in the retina is random

Answer 17

FALSE: there is patterned spacing

Question 18

TRUE or FALSE: APs start at the bipolar cells

Answer 18

FALSE: no APs until the RGCs (retinal ganglion cells)

Question 19

which NT do photoreceptors release? bipolar cells? horizontal cells? amacrine cells? are these NTs excitatory or inhibitory?

Answer 19

• photoreceptors: glutamate (+/-)
• bipolar cells: glutamate (+)
• horizontal cells: GABA (-)
• amacrine cells: glycine (-)

note: D-bipolar cells are depolarizing; H-bipolar cells are hyperpolarizing

Question 20

With which cells do horizontal cells have electrical synapses?

Answer 20

• other horizontal cells
• bipolar cells

Question 21

Which which cells do amacrine cells have electrical synapses?

Answer 21

bipolar cells

Question 22

TRUE or FALSE: ON retinal ganglion cells are excited in the light.

Answer 22

TRUE

Question 23

Draw the synapses of an ON retinal ganglion cell in the dark vs in the light.

Answer 23

slide 15

Question 24

TRUE or FALSE: Glutamate is inhibitory in ON cells and excitatory in OFF cells.

Answer 24

TRUE

Question 25

Why is glutamate inhibitory in ON cells and excitatory in OFF cells?

Answer 25

- ON cells: Glu inhibitory because act on mGlur6 receptors - OFF cells: Glu excitatory because act on AMPA/Kainate receptors

Question 26

Draw the synapses of ON and OFF RGCs in the dark vs light.

Answer 26

slide 15-16

Question 27

True or FALSE: OFF ganglion cells have a higher firing rate in the light

Answer 27

FALSE: in the dark

Question 28

Which kind of receptor is find on H-bipolar cells? What type of RGC do they synapse on?

Answer 28

- ionotropic AMPA/kainate receptors - synapse on OFF RGCs

Question 29

Which kind of receptor is found on D-bipolar cells? What type of RGC do they synapse on?

Answer 29

- mGlur6 receptors - synapse on ON RGCs

Question 30

What kind of receptive fields do RGCs have?

Answer 30

center-surround cell

Question 31

In which organism was lateral inhibition of the ON and OFF cells first shown?

Answer 31

horseshoe crab

Question 32

Which cell mainly mediates surround inhibition or excitation?

Answer 32

horizontal cells (lateral inhibition)

Question 33

Which cell is found in the ON center?

Answer 33

bipolar cells

Question 34

Which cell is found in the OFF surround?

Answer 34

horizontal cells

Question 35

TRUE or FALSE: light in the surround depolarizes an ON center bipolar cell and excites an on-centere ganglion cell

Answer 35

FALSE: hyperpolarizes

Question 36

continue slide 20