Vision Retina 2 Flashcards
major difference between rods vs cones? (what type of vision?)
- rods: scotopic vision (dim light)
- cones: photopic vision (bright light) + colour
scotopic vision vs photopic vision
- scotopic vision = dim light
- photopic vision = bright light
TRUE or FALSE: only rods are found at the fovea and lots of cones are in the periphery
FALSE: only cones are found at the fovea and lots of rods are in the perpiphery
TRUE or FALSE: there are no photoreceptors in the blindspot
TRUE
TRUE or FALSE: there is more convergence from rods than from cones
TRUE
what is the average convergence for rods and cones?
rods = 120:1
cones = 6:1
(ganglion cell:photoreceptor)
What is convergence for rods and cones?
ratio of ganglion cells synapsing on photoreceptors (Ganglion cell:photoreceptors)
How many types of cones are found in placental mammals? what are the types? what are the wavelengths?
- 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
Which cone is the most sensitive? How much more sensitive is it?
L-cone (3x more sensitive than the others)
TRUE or FALSE: there are more S cones than other types of cones
FALSE: there are more L cones
protanopia vs deuteranopia vs tritanopia (which cone are you missin? which colours do you see/ where is the neutral point?)
- 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
Which type of colour blindness is the most rare?
tritanopia
What is s-cone monochromacy?
missing M-cone and L-cone
What is rod monochromacy?
missing all cones
TRUE or FALSE: true colour blindness is tritanopia
FALSE: true colour blindness is rod monochromacy
Which cone are both M cone and L cone variants of?
LWS cone
TRUE or FALSE: the distribution of photoreceptors in the retina is random
FALSE: there is patterned spacing
TRUE or FALSE: APs start at the bipolar cells
FALSE: no APs until the RGCs (retinal ganglion cells)
which NT do photoreceptors release? bipolar cells? horizontal cells? amacrine cells? are these NTs excitatory or inhibitory?
- photoreceptors: glutamate (+/-)
- bipolar cells: glutamate (+)
- horizontal cells: GABA (-)
- amacrine cells: glycine (-)
note: D-bipolar cells are depolarizing; H-bipolar cells are hyperpolarizing
With which cells do horizontal cells have electrical synapses?
- other horizontal cells
- bipolar cells
Which which cells do amacrine cells have electrical synapses?
bipolar cells
TRUE or FALSE: ON retinal ganglion cells are excited in the light.
TRUE
Draw the synapses of an ON retinal ganglion cell in the dark vs in the light.
slide 15
TRUE or FALSE: Glutamate is inhibitory in ON cells and excitatory in OFF cells.
TRUE
Why is glutamate inhibitory in ON cells and excitatory in OFF cells?
- ON cells: Glu inhibitory because act on mGlur6 receptors
- OFF cells: Glu excitatory because act on AMPA/Kainate receptors
Draw the synapses of ON and OFF RGCs in the dark vs light.
slide 15-16
True or FALSE: OFF ganglion cells have a higher firing rate in the light
FALSE: in the dark
Which kind of receptor is find on H-bipolar cells? What type of RGC do they synapse on?
- ionotropic AMPA/kainate receptors
- synapse on OFF RGCs
Which kind of receptor is found on D-bipolar cells? What type of RGC do they synapse on?
- mGlur6 receptors
- synapse on ON RGCs
What kind of receptive fields do RGCs have?
center-surround cell
In which organism was lateral inhibition of the ON and OFF cells first shown?
horseshoe crab
Which cell mainly mediates surround inhibition or excitation?
horizontal cells (lateral inhibition)
Which cell is found in the ON center?
bipolar cells
Which cell is found in the OFF surround?
horizontal cells
TRUE or FALSE: light in the surround depolarizes an ON center bipolar cell and excites an on-centere ganglion cell
FALSE: hyperpolarizes
continue slide 20
