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psyc 301 > Neuroimaging > Flashcards

Neuroimaging Flashcards

1
Q

what is an xray?

A

electromagnetic imaging that reveals iamge based on x-ray absorption

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2
Q

what does an xray show?

A

absorption of x-rays by dif parts of the bodyw

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3
Q

what is cerebral angiography?

A

using a contrasting agent to reveal blood vessels in teh brain

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4
Q

what contrasting agent?

A

iodine

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5
Q

what does cerebral angiography reveal? and help diagnose?

A

blood flow and abnormalities in blood vessels
- stroke and bleeding from strokes

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6
Q

what is CT?

A

imaging technique that uses x-rays to create 3D image of brain

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7
Q

what does Ct show?

A

tissue, fluid, stroke, loss of brain tissue, hydrocephalus

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8
Q

what cant CT differentiate ebtween?

A

gray and white matter - eg brain cancer

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9
Q

what is MRI?

A

imaging tech - uses magentic fields to crete detailed 3D images of the brain

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10
Q

how does Mri work?

A

aligns atoms in the body with magnets then applies second layer that momentarily throws the atoms out of order, and watches them go back into order and measures radiofreq signal produced during realignment w/ large magnetic field
- when atoms move and go back, they release a bit of E and that’s measures
- v expensive

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11
Q

what can mri show?

A

damage from stroe, similar to CT but higher resolution

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12
Q

advantage of mri over ct?

A

ability to overlay plots and study brain areas in multiple participants

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13
Q

main risk of MRI?

A

being around strong magnet

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14
Q

what does MRI provide gross overview of?

A

cranial anatomy and arrangement of neurons

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15
Q

What is diffusion tensor iamging? DTI

A

viewing white matter tracts

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16
Q

how does DTI work?

A
  • studies water mvoement - extracellular and intracellular
  • intracellular follows axons (white matter tracts), while extracellular moves randomly
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17
Q

what is EEG used for?

A

measures epilepsy and sleep states, non-invasive, easy to implement, but noisy signals

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18
Q

time resolution of EEG?

A

fast

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19
Q

spatial resolution of EEG?

A

captures millions/bllions of neurons

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20
Q

limitations of EEG?

A

noisy and cannot measure deeper brains tructures

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21
Q

dif patterns of sleep stages? (3)

A
  • high freq, low amp = awake
  • low frew, high amp = deep sleep
  • REM - sim to awake
22
Q

What is positron emission topography?

A

measures radioactivity in teh brainho

23
Q

how does PET work?

A

person exposed to a radioactive chemical that travels thru blood to brain, scanner picks up on the E released when chem decays = shows where that partic molecule goes in brain

24
Q

name fo machine needed for PET?

A

cyclotron

25
Q

what does cyclotron do?

A

makes chemical molecules radioactive, expensive as decays quick

26
Q

what measures indirect activity?

A

PET and fMRI

27
Q

PET measures?

A

glucose or water use in brain

28
Q

fMRI measures?

A

blood flow and oxygenation in the brain (BOLD)

29
Q

BOLD

A

blood oxygen level dependent

30
Q

another term for BOLD?

A

hemodynamic response

31
Q

spatial resolution o fPET?

A

poor

32
Q

diaschisis? temp or perm?

A
  • hypoactivity in brain areas from loss of inputs from damaged areas
  • temp dysfunction as indirect damage
33
Q

mean difference images in PET?

A

meaningful difs in glucose measurement between stimulation and control conditions
- subtract control from stimulation

34
Q

fMRI measures in terms of blood?

A

oxygenated vs deoxygenated

35
Q

dif magnetic properties between O2’d and deO2’d blood?

A

they relax at different rate, differential relaxation rates

36
Q

fMRI measures in terms of braina ctivity?

A

indirect measure of braina ctivity through blood flow, not measuring APs (so indirect)

37
Q

what is hemodynamic response measured by fMRI?

A
  • relaxation of molecules in the brain, 6 second delay
38
Q

how do astrocytes affect blood flow in the brain?

A

increase CA+ levels in axons
-Ca come in (potent signaling molecule), feet are wrapped around blood vessels to dilate blood vessel
- neurons can’t have direct effect on blood because of BBB, but astrocytes live in both worlds
- axons respond to neuronal signaling

39
Q

why are controsl important in fMRI studies?

A

quality of results depends on quality of controls

40
Q

what is event-related MRI?

A

measurign variables as they move together across many trialsw

41
Q

what is regression in fMRI?

A

examining the rel between a variable and brain activity
- as variable moves, what happens to brain activity - up or down?

42
Q

5 probs in interpreting fMRI studies? (SSTNF)

A

1 spatial averaging - average of averages not accurate per se
2 spatial resolution - 1 voxel is smallest and contains tons fo neurons so not super detailed info
3 temporal resolution - building 3D out of 2D limits how many slices you see and from when, delayed
4 not necessarily necessary - jsut because you see activity doesn’t mean its essential to task being explored
5 focus on increasing an activity - some parts are really active (hippo) so might not be able to see when active and brain is super active when relaxed (DMN)

43
Q

what is resting state functional connectivity?

A

studying braina ctivity at rest and looking for networks of activity or relationships between dif brain areas
- seed region and compare whenever BOLD goes up in seed region, does it go up in corresponding area?

44
Q

Problems with interpreting fMRI studies? (5) RCCAR

A
  • Regional hemodynamics - dif brain areas have dif hemodynamic responses so 6 sec measurement would = wrong data
  • confounds - anxiety, boredom, claustrophobia, falling asleep all affect brain activity
  • confounds - drugs - hard to find someone not affected by some psychoactive drug (caffeine)
  • anticipatory hemodynamics - doing repeptitive tasks, brain learns to anticipate, might send O2 there before it normally would in anticipation of reusing same area
  • reliability - test re-test for MRI not great, order ~30%
45
Q

types of structural imaging? (5)

A
  • X-ray, DTI, cerebral angiography, ct scan, MRI,
46
Q

types of functional imaging? (3)

A
  • EEG, PET and fMRI
47
Q

what’s difference image?

A

avg from all participants
- also subtraction method

48
Q

issue w/ temporal resolution for fMRI?

A

limited by number of images obtained, 1-2 seconds apart each slice vs APs fire m/s
- great for seeing large patterns fo activity, not smaller

49
Q

spatial resolution of fMRI?

A
  • difficulty in distinguishing activity w/in a voxel, 10-15 mil neurons per voxel
50
Q

how is a MRI rep’d statistically?

A

psyc 301 (4 decks)

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