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neuro - block 2 > vision (dr maloney) > Flashcards

vision (dr maloney) Flashcards

1
Q

three key functions of oculomotor system

A
  1. controls what we look at
  2. stabalizes image
  3. alignes both eyes
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2
Q

name all 7 oculomotor muscles

A

6 extra ocular muscles: superior oblique, inferior oblique, superior rectus, inferior rectus, medial rectus, lateral rectus

eyelid: levator palpabrae

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3
Q

what oculomotor muscles are inervated by the oculomotor nerve (III)

A

levator palpabrae, superior rectus, inferior rectus, medial rectus, inferior oblique

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4
Q

what cranial nerve controls the lateral rectus

A

abducens (VI)

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5
Q

what cranial nerve controls the superior oblique

A

trochlear (IV)

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6
Q

pupillary sphincter muscle (function)

A

makes pupile smaller

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7
Q

pupillary dilatory muscle (function)

A

dilates pupil

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8
Q

ciliary muscles (funciton)

A

bends/stretches lense (controlls focus)

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9
Q

rods (general info/what do you know)

A
  • used in dark/dim light
  • have low acuity
  • monochromatic
  • in the periphery
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10
Q

cones (general info/what do you know)

A
  • used in bright light
  • color vision
  • have high acuity (most sharp/clear)
  • concentrated in the fovia
  • 3 types
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11
Q

retinal (def + function)

A

protein found on retina/photoreceptors that changes shape (conformational change) due to light

conformational change causes a chemical cascade: closes sodium ion channels which leads to depolarization. photoreceptors are active in the dark, inactive in light

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12
Q

when are photoreceptors depolarized and releasing neurotransmitter (glutamate)

A

in the dark

Photoreceptor cells are depolarized and constantly release the neurotransmitter glutamate. This is due to the presence of a molecule called cGMP, which keeps sodium channels open, allowing positive ions (Na⁺ and Ca²⁺) to flow into the cell. The continuous influx of ions keeps the photoreceptors in an excited state (depolarized), and they keep releasing glutamate, signaling to the downstream neurons (bipolar cells).

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13
Q

when are photoreceptors NOT depolarized and NOT releasing glutamate

A

in the light

when light hits the photoreceptor, retinal changes its shape, activating the protein opsin. This triggers a biochemical cascade which leads to the breakdown of cGMP. As cGMP levels fall, the sodium channels close, stopping the inflow of positive ions, causing the photoreceptor to hyperpolarize. This hyperpolarization reduces or stops the release of glutamate, altering the signal sent to the bipolar cells and ultimately leading to the perception of light in the brain.

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14
Q

summary (5 steps) of light transduced into neural activity

A
  1. photons hit retinal causing conformational change
  2. opsin (protein) changes shape in response to retinal conformational change
  3. other proteins change their interactions with opsin, triggering signaling cascade that leads to closure of ion channels
  4. voltage of photoreceptor changes and neuron stops releasing glutamate
  5. decrease in glutamate leads to responses (receptor potentials) in bipolar cells (both inhibition + excitation)
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15
Q

name the 4 opsins

A

Lopsin, Mopsin, Sopsin, Rodopson

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16
Q

what color are long wavelength cones (Lopsin/Lcone)

A

red

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17
Q

what color are medium wavelength cones (Mopsin/Mcone)

A

green

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18
Q

what color are short wavelength cones (Sopsin/Scone)

A

blue

19
Q

how many types of cones do mantis shrimp have

A

12

20
Q

how many photoreceptors in retina

A

~125 million photoreceptors

21
Q

how many retinal ganglion cells in optic nerve

A

~1 million

22
Q

the homunculus problem (def)

A

how do we actually UNDERSTAND visual information as opposed to simply being able to represent the visual information over and over in different areas of the brain and not really ‘getting anywhere’

how do we know who is who and how do we translate what we are seeing into having actual meaning for us

23
Q

which cells are in the “horizontal path” in vision

A

horizontal cells, amacrine cells

24
Q

which cells are in the “virticle path” in vision

A

rods + cones, bipolar cells, retinal ganglion cells

25
Q

bipolar cells (in visual system) function

A

pool info from multiple photoreceptors (spacial summation)

26
Q

amacrine cells function

A

larger scale lateral inhibition (than horizontal cells), adjust for light levels (switching btwn rods/cones), motion detection

27
Q

horizontal cells function

A

lateral inhibition (comparing nearby points in space)

28
Q

object detector (def)

A

sensory neurons that look to identify specific objects or stimuli that are relevant for that animal (fly detectors in frogs, faces in humans)

29
Q

filter (def)

A

sensory neurons filter specific types of information on other parts of the nervous system (reduces redundancy)

30
Q

efficient coding (def)

A

sensory neurons recode what we see in a more efficient way to reduce metabolic and physiological demand

31
Q

3 principles of/for vision

A
  1. object detectors
  2. filter(s)
  3. efficient coding
32
Q

who came up with the principles of vision

A

horace barlow

33
Q

fovia (def)

A

place on retina with highest acuity (focus), highest density of cones accross retina (worse night vision)

34
Q

true/false: opsins are g-couples proteins

A

TRUE!

35
Q

what causes color blindness

A

lack of one or more of the opsins

36
Q

the cone mosaic (def)

A

bayer filter (in digital cameras)

cones can’t be in the exact same space so we have a random mosaic of cones in our eyes

37
Q

how many types of horizontal cells are there

A

two

38
Q

what RGC type does fine detail

A

midget/parvocellular

39
Q

retinal ganglion cells (RGC) def

A

outputs info from the retina into the brain (optic nerve)

40
Q

what type of RGC does movement

A

direction selective RGCs

41
Q

what type of RGC does large object tracking

A

parasol/magnocellular cells

42
Q

what type of RGC does luminance

A

intrinsically sensitive retinal ganglion cells (isRGCs)

43
Q

what type of RGC does color

A

bistratisfied/kinocellular RGCs

44
Q

what structure in the brain is responsible for object detectors

A

superior colliculus

neuro - block 2 (9 decks)

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