L2 Flashcards
what are the primary cells of the retina
rods and cones
name all the cells in the retina
retinal ganglion cells, amacrine cells, bipolar cells, horizontal cells, road and cones
cone mediated vision is called
phototopic
what is phototopic vision
high acuity colour vision in good illumination
what is rod mediated vision called
scotopic vision
what is scotopic vision
poorer acuity achromatic vision in low light levels
where are the rods and the cones located on the retina
cones are at the fovea and rods are in the periphery
rods are fairly evenly distributed in the periphery
explain convergence in terms of rods and cones
cones have low convergence therefore they have high spatial resolution
rods have high convergence
other than rods and cones, what other cells are light sensitive
intrinsically photosensitive retinal ganglion cells (ipRGC)
how do intrinsically photosensitive retinal ganglion cells (ipRGC) detect light
these cells utilize the photopigment melanopsin which is maximally sensitive to blue light
these cells have connections to the suprachiasmatic nucleus and are essential for entraining circadian rhythms
how do intrinsically photosensitive retinal ganglion cells (ipRGC) keep us in time with the day night cycle
they send signals to the brain so that during the day they govern the production of cortisol and melatonin at night
where are intrinsically photosensitive retinal ganglion cells (ipRGC) located in the retina
on the bottom section as this is where blue light from the sky would fall
why don’t we see our blind spot where the optic nerve is
because of top down processing
When we close one eye you should see a blind spot. You don’t see this because our brain is completing the image by using other information and guessing what should be these.
what is an excitatory and inhibitory neurotransmitter
glutamate = EPSP (depolerisation)
gabba = IPSP (hyperpolarisation)
which cells in the retina release gabba
amacrine and horizontal cells
what do retinal ganglion cells, bipolar cells, rods and cones release (in terms of neurotransmitter)
glutamate
what is simultaneous contrast
it is the 2 gray squares where one looks darker than the other
why does simultaneous contrast happen
because of lateral inhibition/opponent processing
what are mach bands
when you have strips going from eg dark blue to light blue you interpret seeing a light and dark band when the colour changes
this happens because of lateral inhibition/opponent processing
what is the function of lateral inhibition
The function of lateral inhibition is to enhance contrast to help the nervous system resolve edges of objects
the quality of energy changes depending on what
frequency
what wavelengths of light are we aware of
visible light (400 - 700nm)
this is because these are the only frequency’s that the nervous system is able t interpret and it does so as colour
what are the 3 colours are cones most sensitive to
blue, green and red
what wavelengths are the 3 different cones each most maximally sensitive to
blue = 420 green = 534 red = 564
what % of males and females are red green colour blind
5-10% of males and 0.1% of females
what is the most common form of colour-blindness
deuteranomaly (when you dont see green very well)
what is protanopia
it is the second most common form of colour-blindness which is when you cant see red
how do we see make colours than just red, green and blue
opponent processing
why do you get colour afterimage when you steer at certain colours for a sustained period of time
because when you initially look at the colour you get rapid firing, this dies out over time which means that when you eventually look away you end up with an after image
what is homeostasis
any self regulating process by which an organism tends to maintain stability while adjusting to conditions
how does opponent processing relate to homeostasis
for the example of body temp…
when you get cold you start to shiver which inhibits your ability to sweat
what is approach avoidance
it is an example of opponent processing in motivation
it arises from competition between the drives to pursue the reward and to avoid harm
eg you want to eat the cake but you don’t want to go to the dentist
