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PHGY314 > cortical plasticity > Flashcards

cortical plasticity Flashcards

1
Q

where is most of the cerebral cortex found?

A

burried in the sulci, because the cortex is a thin film about 3mm thick

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2
Q

how big is the cortex if flatted out?

A

as wide as a kitchen table

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3
Q

brain functions are localized, but not entirely what?

A

static

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4
Q

what is Kennard Principle from Margaret Kennard?

A

brain damage early in life is easier to repair than later in life;
there is more cortical plasticity when we are younger

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5
Q

what’s the definition of cortical plasticity?

A

Changes that occur in the function and organization of the cerebral cortex as a consequence of experience

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6
Q

how does the brain adapt after damage?

A

it adjusts its “maps” to the available brain tissue

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7
Q
A
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8
Q

what is crossmodal plasticity? give example

A

plstic changes that occur between sense;
ex if someone looses vision, how does it affect his auditory cortex

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9
Q

what happens to layer 4 of V1 when someone becomes blind from one eye?

A

layer 4 becomes 95% dedicated to the input from the eye that is still open

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10
Q

what happens to layer 4 of V1 if you reopen the eye?

A

after a certain time the layer 4 goes back to normal (representing both eyes the same)

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11
Q

what is the critical period?

A

period during which you have plasticity; pass that, plasticity becomes harder

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12
Q

give an example of the sensitive period

A

The success of treatment for strabismus (lazy eye) early in life;
treating strabismus in adulthood can do more damage than good

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13
Q

why would it be hard for us to have plasticity all of our life?

A

simple things such as walking would not be hardwired anymore

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14
Q

give 2 examples of plasticity in the somatosensory system

A
  1. Changes in cortical maps caused by increasing or decreasing stimulation.
  2. Plasticity from amputation.
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15
Q

changes in cortical representation is a consequence of what?

A

activity

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16
Q

what happened after stimulating a monkey’s finger tip everyday for a while?

A

even just stimulation increased the representation of the finger in the monkey’s cortex

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17
Q

what happens if a monkey looses its 3rd finger?

A

the overall representation of the hand doesn’t change, but the finger details do:
- loose representation of 3rd finger
- increase representation and sensitivity in 2nd and 4th fingers

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18
Q

what happens if you give food rewards associated with 2nd and 3rd finger stimulation?

A

discrimination training of finger 2 and 3 increases their representation in the cortex and their sensitivity at the expense of other fingers

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19
Q

what happens when a monkey is trained on a task that required fine-digit manipulation such as grabbing small objects?

A

the cortical representation of digits expands at the expense of the representation of the wrist and forearm

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20
Q

what happened when they removed the inferior colliculi in immature ferets?

A

it induced new connections from the retina to the MGN, the brain area usually connected to the inferior colliculi.
This caused the auditory cortex to be visually responsive

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21
Q

what is pruning?

A

the process of removing neurons and processes that
are not needed

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22
Q

what is apoptosis

A

is a form of cell death that is normal in development and enables the cells to die without affecting adjacent neurons.

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23
Q

what happened to patient BK who had a visual cortex stroke?

A

he got scotoma (bad vision) in the upper-left field of both eyes, and after a while the stroke damaged area shrunk and he could see almost perfectly

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24
Q

are only young brain plastics?

A

no

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25
Q

when do you stop forming neurons?

A

never; at maturity you still make some, but you just stop making more than you are loosing

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26
Q

describe the 2 visual streams in the brain?

A
  • dorsal stream to parietal cortex: spatial and motion processing, visual control of movement (where)
  • ventral stream to temporal lobe: object and pattern recognition (what)
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27
Q

how did they test to look for what and where processing areas in the non-primary auditory cortex?

A

3 behavioral tasks:
1. acoustic spatial localization (testing for where)
2. auditory pattern discrimination (test for what)
3. acoustic detection task (control)

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28
Q

what areas did they specifically look at in cat for “what” and “where” auditory areas?

A

AAF anterior and PAF posterior auditory fields

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29
Q

name 3 types of permanent neural deactivation

A

physical ablation
chemical (neurotoxins)
electrolytic

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30
Q

name 2 types of reversible neural deactivation

A

chemical (lidocaine, muscimal, GABA)
thermal (thermoelectric-peltier, cryoloop)

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31
Q

what is the cryoloop technique?

A

cooling down of a brain area with cool methanol to reversible deactivate it

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32
Q

what does cryoloop impair?

A

it disrupts calcium uptake at the axon terminal which eliminates synaptic transmission, without impairing axonal transmission

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33
Q

at what temperature is synaptic transmission eliminated?

A

below 20 deg C

34
Q

how long does reversible cooling deactivation take?

A

few minutes only

35
Q

how did AAF and PAF deactivation affect cats in sound localization task?

A

AAF deactivation = not affected
PAF deactivation = can’t localize the sound at all

36
Q

how did AAF and PAF deactivation affect cats pattern discrimination task?

A

AAF deactivation = can’t discern pattern
PAF deactivation = no effect

37
Q

how did AAF and PAF deactivation affect cats sound detection task?

A

no effect (control experiment)

38
Q

from these results, what would be the auditory pathway equivalent of the “where” and the “what” processing areas?

A
  • where = sound localization = PAF
  • what = acoustic pattern discrimination = AAF
39
Q

this experiment shows that it is possible to double dissociate regions of ___-______ ____ involved in spatial and pattern processing

A

non-primary cortex

40
Q

this is true for what kind of animals?

A

mammals with highly developed cerebral cortices. (only tested on that for now)

41
Q

in what lobe are areas for specificity of increasingly complex visual and acoustic stimuli found?

A

temporal lobe

42
Q

what is Area T important for?

A

the accurate discrimination of conspecific vocalizations (same specie)

43
Q

unilateral deactivation of what side of Area T has effects? what are the effects?

A

left area T deactivation causes deficits during conspecific vocalization discriminations

44
Q

does bilateral Area T deactivation affect conspecific vocalization discrimination too?

A

yes, more than only left deactivation

45
Q

bilateral deactivations of what other areas close to area T cause what kind of deficits?

A

A1 = deficit in tones, noise, and vocalization discrimination
A2 = deficit in noise and vocalizations discrimination

46
Q

why does the effect of A1 and A2 deactivation make sense?

A

because A1 projects to A2 which project to Area T

47
Q

what animal has a similar auditory system to humans? who’s is better?

A

cats; their auditory system is better, they can hear ultrasonic sounds

48
Q

what % of cat’s cerebrum is acoustic?

A

20%

49
Q

difference between cat’s and humans brain in general?

A

cats just have a few sulci, humans have a lot

50
Q

what are the main parts of a cochlear implant?

A

magnetized transmitter outside the head, processor around the ear, and a receiver under the skin surface
and stimulator that goes around the cochlea

51
Q

why do you need to get a cochlear implant on both sides if you have a hearing deficit?

A

because non-symmetry is bad for the brain

52
Q

why may it be important for other senses to take up the auditory cortex?

A

to maintain the auditory cortex’s survival

53
Q

what is adaptive cross-modal plasticity?

A

following the impairment of a sensory system, enhance performance is observed in the remaining systems; one or more modalities compensate for the loss of another modality

54
Q

do deaf people see better?

A

they are better at noticing changes in the visual world

55
Q

what part of congenitally deaf cat’s brains are responsible for enhance visual abilities?

A

the auditory cortex

56
Q

how does crossmodal reorganization in congenitally deaf cats affect the ROLE of the auditory cortex?

A

it switches sensory but not behavioral roles of the auditory cortex

57
Q

what happens to congenitally deaf cats hair cells?

A

they die shortly after they are born

58
Q

when do they start training and testing the deaf cats?

A

once they reach maturity (1 yr old)

59
Q

what is ABR and what is it used for?

A

auditory brainstem response: test for brainstem activity following click stimulus

60
Q

how do normal vs deaf cats respond to click stimulus (ABR?)

A

hearing cat: start seeing activity at 20 dB
deaf cat: tiny response to very loud sound from the sound MOTION

61
Q

visual task: what is vernier acuity?

A

telling the difference between a straight line and bars with a slight difference

62
Q

visual task: what is grating acuity?

A

telling the difference between grated pattern and a plain color

63
Q

visual task: what is orientation discrimination?

A

telling when a line is slight orientation or completely straight

64
Q

visual task: what is direction of motion?

A

telling the difference between dots moving straight or at an angle

65
Q

visual task: what is velocity of motion?

A

telling the difference between dots moving fast vs slow

66
Q

visual task: what is detection of movement?

A

telling the difference between static or moving dots

67
Q

in what visual tasks were deaf cats statistically better than hearing cats?

A
  • detection of movement! they can detect slower movement than normal cats
  • visual detection in the peripheral field
68
Q

the functions affected by deafness were all linked to what?

A

motion

69
Q

since the functions affected by deafness were all linked to motion, what stream of the auditory cortex was tested?

A

dorsal stream (WHERE stream)

70
Q

what brain areas consist the dorsal / where stream of auditory cortex? (4)

A

PAF, AAF, A1, DZ

71
Q

what happened when they cooled down A1, AAF, PAF, and DZ in deaf cats?

A
  • cats ability to detect visual stimulus across a visual field decreased a lot
  • cat’s ability to detect movement decreased (less sensitive to movement)
72
Q

what happened when they cooled down each area specifically?

A
  • PAF cooling decreased the ability to detect visual stimulus across the visual field
  • DZ cooling decreased the ability to detect movement
  • A1 and AAF cooling didn’t have much effect
73
Q

cooling down PAF in deaf cats had what effect compared to hearing cats?

A

it eliminated the advantage that the deaf cat had in performing detection across the visual field task

74
Q

what did cooling of PAF on the left side of the cat’s brain cause?

A

eliminated its capacity to localize visual cues on its right side

75
Q

what can we conclude about PAF? posterior auditory field

A

it is important for auditory (already known) localization in hearing cats but in visual localization in deaf cats

76
Q

cooling down DZ in deaf cats had what effect compared to hearing cats?

A

it eliminated the advantage that the deaf cat had in performing detection of movement task

77
Q

what can we conclude about DZ?

A

it is important for detection movement of visual stimulusin deaf cats

78
Q

how did they test for dorsal zone DZ’s involvement in detection of the DIRECTION of motion of a sound?

A

swept broadband noise across speakers, train the cat only to move if the sound is moving in one direction

79
Q

in hearing ats, what did deactivation of each brain area cause?

A

no change in visual tasks! serve has good control

80
Q

we can conclude that what auditory areas become visual and for what tasks?

A

PAF becomes an area involved in visual localization in the peripheral field.
DZ becomes an area involved in the detection of movement.

PHGY314 (9 decks)

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