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Cog neuro (y2s2) > Week 1 Lecture 1 - research methods > Flashcards

Week 1 Lecture 1 - research methods Flashcards

1
Q

What kind of account does cog neuro provide?

A

brain-based account of cognitive processes

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2
Q

What does cog neuro test and not test?

A
  • psychological theories
  • however, uses local blood oxygen and RTs which are just data, this does not tell us how things happen
  • only measures data –> need to combine several methods to actually understand what’s happening (1 method is not superior)
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3
Q

What is the method type, invasiveness and brain property used for EEG/ERP?

A

recording
non-invasive
electrical

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4
Q

What is the method type, invasiveness and brain property used for single-cell and multi-unit recordings?

A

recording
invasive
electrical

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5
Q

What is the method type, invasiveness and brain property used for TMS

A

stimulation
non-invasive
electromagnetic

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6
Q

What is the method type, invasiveness and brain property used for MEG?

A

recording
non-invasive
magnetic

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7
Q

What is the method type, invasiveness and brain property used for PET?

A

recording
invasive
hemodynamic

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8
Q

What is the method type, invasiveness and brain property used for fMRI?

A

recording
non-invasive
hemodynamic

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9
Q

Recording methods vary in terms of spatial and temporal resolution.

Which is more important?

A
  • depends on research questions –> where vs. when
  • should research question to decide primary method of investigation but ultimately multiple methods will be used
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10
Q

What are single-cell recordings?

A
  • small electrode implanted into axon (intercellular) or outside of axon membrane (extracellular)
  • records neural activity from population of neurons
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11
Q

How are recording made for single-cell recordings?

A
  • measure the electrical potential of nearby neurons that are close to the electrode proximity
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12
Q

Can electrodes measure a single neuron in a single-cell recording?

A

no
electrodes aren’t yet precise enough for this
instead measurements come from a general population

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13
Q

Who are single-cell recordings used on?

A

animals

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14
Q

What is the most used neuroimaging technique in humans?

A

EEG

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15
Q

What are EEGs?

A
  • measure electrical activity of the brain by recording from electrodes placed on the scalp
  • resulting traces known as an EEG –> represent an electrical signal form a large number of neurons
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16
Q

What type of research is EEGs often used in?

A

baby research

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17
Q

Do EEGs require specific scalp placements?

A

Yes

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18
Q

What do EEG signals represent?

A

the change in the potential difference between to electrodes placed on the scalp in time

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19
Q

Are several trails used in an EEG?

A

yes
the EEG obtained on several trails can be averaged together (time locked to the stimulus) to form an event-related potential (ERP)

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20
Q

What are ERPs?

A

voltage fluctuations that are associated in time with a particular event e.g., visual, auditory etc.

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21
Q

Why do EEGs need to be averaged out?

A

to cancel out the background noise that it also measures
this means that the ERP generated in only measures signals related to the target stimulus

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22
Q

Are different ERP peaks associated with different aspects of face processing? Give examples

A

Yes
- N170 is relatively specialised for faces recorded from right posterior superior temporal sulcus (right PSTS)
- P300 peaks for famous and familiar faces

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23
Q

What did a comparison between the ERPs from patients with Alzheimer’s and control subjects find?

A
  • reduced P300 is seen for the demented patients at each electrode site
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24
Q

What is an MEG?

A
  • measures the magnetic fields produced by electrical activity in the brain via extremely sensitive devices known as SQUIDs.
  • these measurements are commonly used in research and clinical settings
  • excellent temporal and spatial resolution however is very expensive and so not as popular in research
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25
Q

What is an MRI?

A

uses differential magnetic properties of types of tissue and blood to produce images of the brain

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26
Q

What are the 2 types of MRI?

A
  • structural
  • functional
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27
Q

What is a structural MRI?

A
  • different types of tissue have different physical properties
  • these are used to create static maps of the brain
  • cannot say a lot about behaviour
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28
Q

What is a functional MRI?

A
  • temporary changes in brain physiology associated with cognitive processing
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29
Q

What are the 2 types of functional MRI?

A
  • fMRI
    -PET
30
Q

What is PET?

A
  • measures local blood flow (rCBF)
  • radioactive tracer injected into blood stream
  • areas of high radioactivity are associated with brain activity –> based on blood volume
31
Q

How long does it take the radioactive tracer that is injected to peak (PET)

A

30 seconds

32
Q

What does it mean when it is said that PET scans measure radioactivity based on blood volume?

A
  • brain is constantly in need of oxygen
  • oxygen brought to brain via blood
  • it is thought that blood flows to the areas in the brain most in need of oxygen
  • will see the radioactive tracer in these areas as it entered the blood
33
Q

What is an fMRI?

A
  • directly measures the concentration of deoxyhaemoglobin in the blood
  • called the BOLD response
34
Q

What is the BOLD response?

A

blood oxygen level dependent contrast

35
Q

What are changes in the BOLD response over time called?

A

the hemodynamic response function

36
Q

When does the hemodynamic response function peak? What does this limit?

A
  • peaks in 6-8 seconds
  • limits the temporal resolution of the fMRI
37
Q

Does fMRI study correlation or causation?

A

studies correlation between brain activity and stimulus timings

38
Q

What can fMRIs be used to produce?

A

activation maps showing which parts of the brain are involved in a particular mental process

39
Q

In an fMRI, what is activity measured in?

A

voxels (volume pixels)

40
Q

What are voxels?

A

the smallest distinguishable box-shaped part in 3D image

41
Q

In order to infer functional specialisation, what do we need to compare?

A
  • relative differences in brain activity between 2 or more conditions
  • this involves selecting a baseline or comparison condition
42
Q

When is a brain region active?

A
  • if it shows a greater response in one condition relative to another
  • is the experimenter chooses an inappropriate condition the regions of activity will be meaningless
43
Q

How are fMRI studies designed?

A

consider what are the brain regions involved in specific area of interest e.g., for words you would consider brain regions involved in:
- recognizing written words
- saying the words
- retrieving the meaning of the words

44
Q

What are cognitive subtractions?

A

activity in a control task is subtracted from the activity in an experimental task

exp - control

45
Q

What is a problem for cognitive subtractions?

A

the difficulty of the baseline task

46
Q

What did a study by Devlin et al., find when comparing two imaging methods in a semantic task?

A
  • fMRI results activated brain areas such as cerebellum, IFG, BA8, rIFG
  • PET scan results activated different areas such as the anterior temporal pole and inferior temporal gyrus (did also activate cerebellum and IFG)
47
Q

What is DTI?

A
  • an imaging method that uses a modified MRI scanner to reveal bundles of axons in the living brain
  • imaging of how the brain is connected
  • we can visualise connections in the brain
48
Q

What does DTI measure?

A

white matter organisation based on limited diffusion of water molecules in axons

49
Q

What is fNIRS?

A
  • measures the same BOLD responses as fMRI but in a different way
  • “light” in infrared range passes through skull and scalp but is scatter differently by oxy- v. deoxyhaemoglobin
50
Q

What are some pros and cons of fNIRS over fMRI?

A

pros
- more tolerant of head movement

cons
- can’t image deep structures

51
Q

What is iEEG / ECoG?

A
  • intercranial recording
  • gives high spatial and temporal resolution
  • record directly from inside the human brain when people are undergoing neurosurgery
  • they are placed to locate the seizure and map function
  • recording straight from the cortical surface ~ 10 of thousands of neurons
52
Q

What did a study by Mukamel et al. find using intercranial recoridngs?

A

neurons in supplementary motor area (SMA) and hippocampus both respond to observation and execution actions

role of hippocampus was surprising

53
Q

What is TMS?

A

a means of disrupting normal brain activity by introducing neural noise

54
Q

Who enabled to development of TMS?

A

Faraday and invention of Farady’s coil –> alternating currents

55
Q

How does TMS work?

A
  • TMS coil has magnetic field pulse which changes
  • this induced an brief electric field on a second coil which induces a current
  • continued alternating current allows TMS to work
  • needs to be switched on and off at a high rate
  • this interferes with the electromagnetic fields in the brain
56
Q

When applying TMS to areas of the brain that support reading, what do we expect to see?

A
  • TMS will interfere with the relevant neural signal
  • efficacy of the neural signal will be degraded
  • observe change in behaviour –> RT change - it will take us long to read
57
Q

What are some advantages of TMS?

A
  • interference technique
  • transient and reversible
  • control location of stimulation
  • establishes a causal link of different brain areas and a behavioural task
58
Q

What was the method and results of a TMS study on language?

A
  • ppts left or right language dominant
  • picture-word verification task
  • TMS applied

Results:
- language disruption correlated with degree and side of lateralisation
- Left dominant, left TMS = slower
- Left dominant, right TMS = faster
- same pattern found for right dominant

59
Q

What does the results from the TMS language study suggest support for?

A

Hemispheric balance theory:
- 2 hemispheres inhibit each other
- stimulation of dominant side = slower
- stimulation of other side = faster
- can be applied to all brain functions

60
Q

What is TES?

A
  • uses low level currents applied via scalp electrodes to specific brain regions
61
Q

There are several different protocols for TES, what are they?

A
  • transcranial direct current stimulation (tDCS)
  • transcranial alternating current stimulation (tACS)
  • transcranial random noise stimulation (tRNS)
62
Q

What is the current generator in TES?

A

a battery delivers constant current of up to 2mA, with 2 sponge electrodes in saline solution.
Simulation is less focal and very safe

63
Q

When applied in sessions of repeated stimulation, what can tDCS lead to?

A

changes in neuronal excitability that outlasts the stimulation itself

has promising results in therapy: migraines, dementia, depressions etc.

64
Q

What are the different types of direct current that can be applied in tDCS?

A
  • anodal –> facilitation effects
  • cathodal –> inhabitation effects
  • Sham (control) –> 30s stimulation
65
Q

What does Anodal stimulation inhibit?

A

GABA –> inhibitory neurotransmitter so leads to faciliatory effects

66
Q

What does Cathodal stimulation inhibit?

A

Glutamate –> excitatory neurotransmitter so leads to inhibitory effects

67
Q

What does tACS use?

A

low level alternating current applied via scalp electrodes to specific brain regions

68
Q

What is the rational behind tACS?

A
  • the entrainment (synchronization) of internal brain rhythms with externally applied oscillating fields
  • these fields cause phase-locking of a large pool of neurons, leading to increases of neural synchronization at the corresponding frequency
69
Q

What can tACS be used to induce?

A

lucid dreaming

70
Q

When people lucid dream, what do they show?

A
  • overlap of waking consciousness transfer into the dream and is reflected in brain waves
  • show gamma waves in the frontal cortex –> activity pattern which is linked to consciousness but absent during sleep and normal dreaming
71
Q

What did a study which applied tACS to participants 2 minutes after entering REM sleep find?

A
  • EEG data showed that the brain’s gamma activity increased during stimulations with 40Hz and to a lesser degree during stimulation with 25Hz
  • insight and dissociation were induced using 40Hz
  • control induced using 40Hz and 25Hz

Cog neuro (y2s2) (11 decks)

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