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Neurology - professional - batt > Physiology of Vision > Flashcards

Physiology of Vision Flashcards

1
Q

What are the lateral cells in the retina?

A

horizontal cells and amacrine cells

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2
Q

What is the function of horizontal cells?

A

receive input from photoreceptors and project to other photoreceptors and bipolar cells

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3
Q

What is the function of amacrine cells?

A

receive input from bipolar cells and project to ganglion cells, biopolar cells and otehr amacrine cels

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4
Q

What is transduction?

A

the conversion of electromagnetic radiation to neural signals

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5
Q

What are the 4 regiosn of photoreceptrs?

A

outer segment; inner segment; cell body and synpatic terminal

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6
Q

What is the resting membrane potenetial of photoreceptors as compared to other neurons?

A

depolarised

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7
Q

What happens to the membrane potenetial of photoreceptors in response to light?

A

hyperpolarises

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8
Q

What is the dark current?

A

constant flow of sodium through a cGMP channel that is open in the dark and closed in the light

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9
Q

What is the visual pigment in rods called?

A

rhodopsin

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10
Q

What is rhodopsin composed of?

A

retinal and opsin

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11
Q

What happens to retinal in the light?

A

changes from 11-cis-retinal to all-trans-retinal

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12
Q

How does the activation of retinal cause closure of cGMP channels?

A

activats transducin and a molecular casacade that decreases cGMP

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13
Q

What is the neurotransmitter in the retinal ganglion cells?

A

glutamate

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14
Q

What is visual acuity largely determined by?

A

photoreceptor spacing

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15
Q

What are the differences between the distribution of rods and cones?

A

more convergence in rod system which increases sensitivity whilst decreasing acuity

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16
Q

What are the 3 types of cone?

A

short-wave; middle-wave and long-wave cones

17
Q

What type of glutamate receptor is foudn in OFF bipolar cells?

A

ionotropic

18
Q

What type of glutatmate receptor is foudn in ON bipolar cells?

A

metabotropic

19
Q

What is the difference between ON and OFF bipolar cells?

A

ON bipolar cells are activated light ON (less glutamate) whereas OFF bipolar cells are activated by light OFF

20
Q

What is the function of lateral inhibition?

A

exaggerates the difference in stimulus intensity detected by adjacent neurons, aiding localisation

21
Q

What is the function of centre-surround organisation?

A

emphasis contrast sharpening boundary between objects of different luminance

22
Q

What ar ethe 2 types of retinal ganglion cell?

A

M-type ganglion cell and P-type

23
Q

What is the difference between M-type and P-type ganglion cells?

A

M-type have much larger receptive fields, they conduct APs more rapdly and are more sensitive to low contrast stimuli. thye respond to stimulation of their RF centre with a burst of APs whereas P-type respond with a sustained discharge

24
Q

What are the 2 typeso of colour opponency?

A

red vs green and blue vs yellow

25
Q

What type of retinal ganglion cells are color-opponent cells?

A

P-type and nonM-nonP

26
Q

How many layers does the lateral geniculate nucleus have?

A

6

27
Q

What are the ventral layers of the LGN (1 and 2) called?

A

magnocellular LGN layers

28
Q

What are the dorsal layers (3-6) of the LGN called?

A

parvocellular LGN layers

29
Q

Where do nonM-nonP type retinal ganglion cells project in LGN?

A

konio-cellular layers– numerous tiny neurons just ventral to each layer

30
Q

Where do magnocellular LGN neurons project to in the visual cortex?

A

layer IVCa

31
Q

Where do parvocellular LGN neurons project to in the visual cortex?

A

layer IVCb

32
Q

Where do koniocellulal LGN axons project to?

A

layers II and III

33
Q

Where are the first binocular neurons found in the visual cortex?

A

in layer III

34
Q

What is the competition hypothesis?

A

connections from the two eyes compete with each other in cortex

35
Q

What is the function of direction selectivity of the striate cortex?

A

analysis of object motion

Neurology - professional - batt (40 decks)

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