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PSYC 211 > L3 > Flashcards

L3 Flashcards

1
Q

how does the visual world map onto the retina

A

it is inversely projected onto the retina

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2
Q

where do 90% of the fibers in the optic nerve terminate

A

the lateral geniculate nucleus of the thalamus

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3
Q

what allows for mapping of the visual field

A

the response of cells in the LGN (on and off centre surround)

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4
Q

what is on centre

A

when light of the correct orientation falls onto the centra it will increase the cells firing rate and when it falls on the surround it will decrease the firing rate

this is the opposite for off centre

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5
Q

what is retinotopic organisation

A

the visual world is mapped onto the retina > LGN relationships are maintained in the nervous system

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6
Q

what is the patteren for LGN retinotopic mapping

how will the cells be active hen something moves across the visual field

A

when an object moves across the visual field the cells that respond are usually in a linear pattern

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7
Q

where do fibers from the LGN project to

A

V1 / striated cortex / brodmann’s area 17 / primary visual cortex

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8
Q

where is V1 located

A

at the very back of the occipital lobe. you cant see most of it as it is on the inside of the brain

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9
Q

what cells are found in V1

A

simple and complex cells

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10
Q

what is a simple cell

A

these respond to elongated bars or edges of light

these are orientation selective and have separate on and off subregions

these cells can be binocular or monocular

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11
Q

what are complex cells

A

these are orientation selective

have spatially homogenous receptive feild therefore they have no sporate on/off sub regions

nearly all of these cells are binocular

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12
Q

list the order of cells information passes through in the brain

A

retinal ganglion cell –> LGN –> simple cell –> complex cell

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13
Q

what is meant by the columnar architecture of V1

A

the cortex has many layers. if you look at cells at right angles to the surface to see what they respond to, they all have a receptive field which overlaps and they all have the same orintation selectivity (they all involved in processing the same part of the visual field)

when you look at cells in the horizontal plane they shift systematically and as the position of the receptors fields and preferred orintation slowly change. this shows that the cells respond to slightly different things indicating that they are responsible for a different parts of the visual world

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14
Q

what does retinotopy mean

A

remapping of the retinal image onto the cortical surface

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15
Q

which region of the retina has a greater magnification factor (used more of V1)

A

the foveal region

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16
Q

a local group of neurons in V1 represents what

A

a point in the visual field

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17
Q

what is an example of topographic organisation

A

retinotopic mapping

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18
Q

what is topographic organisation

A

an ordered representation of the sensory environment where spatially adjacent surfaces are represented in adjacent positions in the brain

19
Q

what are the 2 reasons why retinotopic mapping is the most efficient way for us to perceive vision

A

space saving and local processing

20
Q

what takes up the most space in the brain

A

brain volume is largely driven by axon volume because myelination takes up a lot of space

therefore reducing axon length provides space form more neurons and conserves metabolic resources

21
Q

what is the most efficient way to keep axon length short in the brain

A

axon length is shortest when neurons that share dence connectivity are clustered together

eg like having all the cells for processing the visual field in V1

22
Q

how does retinotopic mapping allow for local processing

A

cells are all clustered together in V1. the proximity facilitates processing such as lateral inhibition

23
Q

what are sound waves

A

pressure pulses that travel at 340 m/s

24
Q

what is the human range of hearing

A

20 - 20,000 Hz

25
Q

describe age related hearing loss in men and women

A

it is much worse in men than it is for women

26
Q

a 10 dB decrease in hearing does what to the perceived loudness

A

1/2’s it

27
Q

name the structures of the outer ear

A

ear canal

28
Q

name the structures of the middle ear

A

meleous, incus and stapies

29
Q

name the structures of the inner ear

A

eustachian tube, coclia, semicircular canals

30
Q

what are the nerves of the ear

A

vestibular nerve, facial nerve, auditory nerve

31
Q

explain the effect of the sound wave in the cochlea

A

the coclia is fluid filled. vibrations produce waves which bend the outer hair cells which amplify the weak mechanical signal

then the inner hair cells transduce that information. they do this because the vibrations cause them to bend which open ion channels which causes an electrical signal

32
Q

how is the cochlea tonotopically mapped

A

the base is for high frequency’s and the apex is for low

33
Q

what is the pathway of sound information

A

cochlea –> brainstem –> midbrain –>medial geniculate nucleus of the thalamus (forbrain) –> auditory cortex

34
Q

what happens at the inferior colliculus

A

this is where sounds that your body is producing is subtracted from your auditory signal

eg this is why you may not notice that you are chewing loud

35
Q

what is the medial geniculate nucleus

A

this is where attention is controlled

eg if a sound comes from one side, this is the location that makes you turn to that side

36
Q

describe topographic representation in the primary auditory cortex

A

anterior is for low frequencys and posterior is for high

37
Q

why is it important that the auditory cortex is topographically mapped (5 points)

A

it reduces axon length because sounds that are close in frequencys and processed together

facilitates processing (lateral inhibition)

allows sound to be encoded on the basis of time/frequency changes

scene analysis allows you to detect different frequency’s in the environment (low = footsteps, high = birds)

detection of beat for social cohesion (eg the base in music makes you dance which forms social bonds)

38
Q

what is top down processing

A

using information from a higher level mental process and prior experience

39
Q

what is bottom up processing

A

processing that begins with the sense receptors

40
Q

what % of inputs to the visual cortex are top down

A

6%

41
Q

is the primary auditory cortex larger in old world monkeys or humans

A

old world monkeys (macaques)

however in humans the surrounding belt and parabelt areas are about 10x larger

42
Q

where does the auditory cortex get its information from

A

most connectivity is top down as around 66% is from other cortical areas

43
Q

why does the auditory system use so much top down processing

A

allows for context and procedural demands to bias perception

allows for integration of multisensory input

PSYC 211 (26 decks)

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