Methods Flashcards

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1
Q

perturbation methods

A

change the brain -> causal relation

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2
Q

monitoring methods

A

measure the brain -> correlation

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3
Q

limitation van damage to the brain als info over cognition

A

experimenter heeft geen control:
- damage not focal (single lesion can have a diverse effect)
- not generalizable (not every patient is the same)

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4
Q

wat moet je doen om damage als exp. hogere validiteit te geven

A

groups of patients en dan kijken naar wat ze allemaal in gemeen hebben qua loss of function

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5
Q

lesions maken in animals als researcher limitations

A
  • animals need time to learn
  • animals not as complex behaviour
  • ethical
  • interpretation problems: diachisis (damage to one neuron leads to decreased activitiy in another neuron); damage to fiber tracts bv heeft een hoop andere gevolgen
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6
Q

wat zijn de 3 perpetuating methods

A
  • lesions
  • pharmacological
  • brain stimulation
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7
Q

pharmacological perpetuations

A

interfere with neurotransmitters that influence a certain cogntion.
- chronic drug abusers
- trials met drugs

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8
Q

agonist

A

activates the same receptors

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9
Q

antagonist

A

deactivates the receptors

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10
Q

limitation of pharmacological

A

unspecific

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11
Q

Penfield wat deed hij

A

intracranial brain stimulation -> somatotopic organization

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12
Q

optogenetics

A

Genetic material responsible for making ligand-gated ion channels is extracted and inserted in a virus. This virus is injected in a brain area and will infect the targeted neurons. The inserted genetic material will lead to the production of channelrhodopsins in the membranes of the infected neurons. Dit is intracranial brain stimulation

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13
Q

voorbeeld extracranial brain stimulation

A

TMS

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14
Q

TMS

A

Strong current is sent through coil and produces a strong
magnetic field. This field induces a changing electrical field in the
underlying brain area and causes neuronal activity ( e.g. motor
activity).
-
Single pulse TMS : during the experiment, a TMS pulse is
delivered on each trial (e.g., when a stimulus is presented).
-
Repetitive TMS : before the start of the experiment, a train of
pulses is delivered that changes the underlying brain area for
longer duration.

The effect of TMS depends on the strength of the pulse. A strong
pulse causes temporary ‘lesions’; weaker pulses can sometimes
facilitate activation.

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15
Q

TMS + en -

A

+ great temporal resolution
- bad spatial resolution
- only superficial structures
- contractions in head and neck: hard to mimic for control condition and annoying
- heeeel soms epileptic seizure

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16
Q

Transcranial Electrical Stimulation (TES)

A

ook wel tDCS (transcranial Direct Current Stimulation).

small electrical current is applied directly
to the scalp. Effects can last for an extended period
and is used in research and to treat clinical
problems (e.g., depression).

maar niet duidelijk of dit ook echt sterk genoeg is.

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17
Q

monitoring methods

A

direct recordings
EEG
MEG
PET
fMRI
optical brain imaging

18
Q

single cell recordings

A

electrical recordings directly in the brain (vooral animal research). laten zien met peristimulus histogram

19
Q

tuning curves

A

a neuron is stimulated in different dimensions (bv orientation) en dan kijken hoe hij op verschillende versies reageert.

20
Q

electroencephalography:

A

cap, electrical potential recordings outside of the skull

21
Q

what do we measure with eeg

A

membrane potentials –> als veel neuronen op hetzelfde moment signalen krijgen (EPSP en IPSP) –> local field potential LFP -> sterke LFPs kunnen gemeten worden.

22
Q

dus wat meet eeg wel en wat niet (2 dingen)?

A

niet: actiepotentialen en intracellular, maar wel: combined input to dendrites of neurons, dus extracellular

23
Q

In welke orientation meet je EEG?

A

alleen als de electrode perpendicular is to the signal -> dus alleen in gyri.

24
Q

wat voor 2 dingen kun je uit een EEG signaal halen

A
  1. oscillations: different waves with different frequencies (dus de verschillende waves uit de som halen)
  2. ERPs: event related potentials -> small voltage differences in an ongoing EEG wave, triggered by sensory and cognitive events (dus de verschillen tussen ‘standaard’ gaande wave, wanneer er iets gebeurd)
    –> The EEG data is ‘cut’ in portions (called epochs ) and aligned to the onset of the
    stimulus presentation. The epochs are averaged and the signal that is most common in all epochs remains.
25
Q

topographic map

A

laat zien hoe de activiteit bij de electroden verandert over tijd en space -> per brain region (spatial and temporal patterns of ERPs

26
Q

3 electrical methods for monitoring

A

direct recordings, EEG, MEG

27
Q

limitations EEG

A
  • gaat op level van electrodes, niet op level van brein
  • inverse problem: het signaal kan van veel verschillende brain activation combinations komen
  • low spatial resolution: door hindernis CSF, skull, hair etc.
  • only superficial brain structures
28
Q

MEG

A

magnetoencephalography.
- neurons parallel to the skull (EEG = perpendicular)
- electrical current produces magnetic field
- magnetic field geen last van hindernissen zoals skull, dus:
also deeper structures
better spatial resolution than eeg

29
Q

dus MEG vs EEG

A
  • EEG measures electrical potentials/activity, MEG measures the magnetic field outside of the head
  • EEG bad spatial resolution, MEG good
  • EEG only superficial, MEG deeper structures
  • EEG cheap, MEG expensive
  • both EEG and MEG have the inverse problem
30
Q

limitations MEG

A

expensive
subjects movements are restricted by the machine

31
Q

3 methods for monitoring that have to do with metabolism of the brain: energy

A

PET, fMRI, optical brain imaging

32
Q

PET

A

radioactive tracer injected in bloodstream, zo kun je zien waar meer bloed heen gaat. tracer is more present in active brain regions. detectors measure the gamma rays that are created.

33
Q

limitations PET

A

scary for participants (needles, radioactive), expensive!, slow process (in bloed opnemen etc)

34
Q

wat is het enige design dat kan bij PET

A

blocked design (door langzaam) -> In a blocked design, many trials from one condition
are presented in a block. This allows the integration of activity across time. The brain activity in one block is compared to the activity of another block that has trials
from another condition. In PET, the tracer needs to decay between different
blocks. This takes a long time (about 10 minutes).

35
Q

fMRI werking

A

bloed met oxygen has different magnetic properties than blood without oxygen. active brain area -> more oxyhemoglobin -> fMRI meet dit.

36
Q

verschil PET en fMRI

A

PET zie je het hele brein areas, bij fMRI zie je een klein gebiedje gekleurd.
fMRI kan je vaker doen omdat het niet radioactieve tracers zijn etc.
fMRI kan je veel sneller switchen tussen condities, hoeft geen blocked design zoals bij PET

37
Q

event-related designs

A

change conditions on a trial by trial level.

38
Q

fMRI is heel duur, maar samen met EEG de meest gebruikte techniek.

A

oke

39
Q

2 fMRI methods

A
  • Multivoxel Pattern Analysis : application of machine learning techniques to disentangle
    activation patterns.
  • Principal and Independent Component Analysis : Decompose data to find brain areas that behave similarly.
40
Q

Structural equation modeling

A

causality based on anatomical connections

41
Q

Dynamic causal modeling

A

causality based on functional connections

42
Q

structural images of the brain (twee dingen)

A
  1. PET laat zien hoeveel receptors er zijn
  2. diffusion tensor imaging DTI: reveals the white matter tracts