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Cognitive > Cognitive Neuroscience > Flashcards

Cognitive Neuroscience Flashcards

1
Q

What process is performed by the myelin sheath of a neuron?

A

Insulates the axon and maintains the speed of communication of neural impulses

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2
Q

EEG signals are produced by ______ synchronisation of cortical field activity and are measures as changes in ______, recorded at the scalp

A

Partial, voltage

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3
Q

What is an advantage of fMRI?

A

structural data can be acquired in the same session

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4
Q

Working with data from individuals with brain damage is known as…

A

Neuropsychology

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5
Q

What technique causes a delay of around 4 seconds between brain activity and response detection?

A

fMRI

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6
Q

What does EEG enable us to assess?

A

The precise timing of neural activation

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7
Q

What is the region located at the back of the brain that processes visual information?

A

Visual cortex

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8
Q

The BOLD signal detects how much _______ is in a brain region

A

Oxygen

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9
Q

What is an disadvantage of MEG?

A

Cost £

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10
Q

SAQ: how do we know when are where face processing occurs in the brain?

A

-Using EEG
- each visual change= an event/stimulus onset
- neurons are responding to this stimulus onset
- Electrodes put on head by 10 20 system, electrodes have numbers on them= universal system used to place
- electrodes w odd numbers = on the left, electrodes w even = on the right
= if image on right hand of screen= would see very strongly on left hemisphere at back of the head

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11
Q

SAQ: What does an Event Related Potential (ERP) measure? Provide an example of an ERP study that has told us something about a cognitive mechanism

A
  • ERP measures a change in electrical activity
  • its the average of many single trial epochs
  • if signal is clear and strong= see a response to stimulus
    e.g. N170
  • electrodes over partial area= signal changes depending on what you see
    between 100 and 200ms = process facial info a lot stronger than other images, call this strong response to faces in these regions at this particular time N170
  • difference between if face is upright or inverted
  • if upright= process it earlier than inverted
  • told us when processing faces we use N170= in the ‘sts’ part of brain
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12
Q

What is the link between cognitive psychology and neuroscience?

A
  • Cog= trying to understand the process of cognition
  • Neuroscience= biological processes, scientific study of the nervous system, structure of the nervous system
    THE LINK THEREFORE:
  • how brain structures and processes mediate cognitive behaviour
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13
Q

What does cognitive neuroscience tell us ?

A

Where in the brain things are happening, how the processes work, how the neural networks work, how info travels around the brain

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14
Q

What can EPRs tell us ?

A

Where and when processing happens in the brain

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15
Q

What is VEP?

A

Visual Evoked Potential
= a specific type of Event Related Potential that is a neural response to the presentation of a visual stimulus
= therefore the VEP is a ERP

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16
Q

Is fMRI a direct measure of brain activity?

A

No- which is a disadvantage

  • A direct measure would measure the activity itself e.g. a single electrode recording would directly measure the neural firing associated with a particular aspect of cognition
  • fMRI measures a physiological response to the brain activity i.e. after the activity happens there is a 4s delay before oxygenated blood flows back to the region where the brain activity took place
  • Then work backwards to try and infer what brain activity has caused the signals detected = the inverse problem
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17
Q

How is are electrodes set up in EEG?

A

Electrodes containing odd numbers will be placed over the left hemisphere and electrodes with even numbers will be placed over the right hemisphere

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18
Q

What is N170?

A
  • happens at 170ms after stimulus onset
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19
Q

Why is EEG and fMRI used for N170?

A

Because fMRI can identify a location of processing via the BOLD response but takes around 4s to appear
The N170 happens at 170ms after stimulus onset so fMRI cant measure directly
- THEREFORE use EEG as well as fMRI

20
Q

How do we find out about the brain structure?

A

Autopsy, structural magnetic resonance imaging (MRI)

21
Q

How do we find out about brain function?

A

Scalp- located electrodes = in EEG and ERPs, fMRI, MEG, TMS,PET

22
Q

How do we investigate Neuropsychology?

A

Data from individuals with brain damage

23
Q

What is fMRI?

A

Functional magnetic resonance imaging

  • Neurons are active and burn energy, and are automatically replenished via blood after a few s
  • Blood contains haemoglobin (which contains iron) so it’s possible to detect blood flow= can distinguish between o2 rich and o2 depleted blood
  • Measure the BOLD (blood o2 level dependent) response in the scanner= can work out what parts of the brain were recently active
24
Q

What are the advantages of fMRI?

A
  • Tells us which parts of the brain are used in task
  • Reasonable temporal resolution = 4s
  • Get structural data within same session
25
Q

What are the disadvantages of fMRI?

A
  • Claustrophobic, noisey, movement artifacts (difficult for button presses)
  • Can’t have any metal based equipment for stimulus present
  • BOLD isn’t a direct measure of activity, and care should be taken interpreting it
26
Q

What is TMS?

A

Transcranial Magnetic Stimulaton

- uses large portable magnet placed next to the head

27
Q

What is TMS?

A

Transcranial Magnetic Stimulation
- uses large portable magnet placed next to the head
- magnet turned on would interfere with the function of your brain in particular regions
- non-invasive method causing depolarization or hyperpolarisation of neurons in the brain i.e. increase/decrease activity
- can be seen via twitched in limbs= used motor evoked potential
- uses electromagnetic induction to induce weak electric currents in the cortex
(invented at sheff uni )

28
Q

What can TMS produce?

A

A simulated temporary ‘lesion’ (for a few s) of the brain region by preventing normal function of that region. Thought to be without any long-lasting (adverse) effects

29
Q

What are the advantages of TMS?

A
  • Near portable

- Can ‘stimulate’ or ‘lesion’

30
Q

What are the disadvantages of TMS?

A
  • Difficult to specify precise regions

- Only surface regions- cant look at function in the midbrain

31
Q

What is MEG?

A

Magnetoencephalogram

  • The pyramidal cells (pyramidal neurons) of the cortex, when active, generate a significant magnetic field
  • MEG records these magnetic fields
  • Magnetic fields are less distorted by the scalp than electric fields (which we use to measure EEG)
32
Q

What does EEG and MEG need?

A
  • For EEG and MEG need to have synchronous firing of 10,000s neurons to produce a field which is large enough to measure, they all need to be working together
33
Q

What are the advantages of MEG?

A
  • Excellent temporal resolution

- Good spatial resolution (not distorted by the scalp and for whole brain) especially if combined with MRI

34
Q

What are the disadvantages of MEG?

A
  • Cost £££££££££

- The inverse problem for finding what causes what = not a direct measure of the activity

35
Q

What is EEG?

A

Electroencephalography

  • Measures electrical signals generated by the brain through electrodes placed at the scalp
  • EEG signals are produced by partial synchronisation of cortical field activity and are measured as changes in voltage, recorded at the scalp, over time
  • Electrodes placed on scalp, connected with gel or conductive solution
  • The amplifier measures the difference in voltage between the active electrode and a reference electrode
36
Q

How are the electrodes positioned on the scalp ?

A

By the 10-20 system, electrodes have numbers on, electrodes containing odd numbers will be placed over the left hemisphere and electrodes with even numbers will be placed over the right hemisphere

37
Q

What are the advantages of EEG?

A
  • Good temporal resolution
    -Less subject to motion artifacts, not claustrophobic, can be used even by infants.
    Major artifact= eyes blink- but can be eliminated automatically via monitoring eyelid
38
Q

What are the disadvantages of EEG?

A
  • Weak spatial resolution
  • Inverse problem- given a pattern of activity, how do you determine which brain regions caused it? = by signal processes = can be quite complex
39
Q

What is ERP?

A

Event related potential
= the average of many single trial epochs
- Event= stimulus
- Related= how links
- Potential= as measuring a change in electrical activity
- If signal is clear and strong= see response to stimulus

40
Q

What is N170?

A
  • Electrodes over partial area
  • between 100 and 200ms = processing facial images a lot more strongly than the other images
  • Call this strong response to faces in these regions at this particular time N170= an ERP component
  • Can show the difference between if a face is upright or inverted
  • If upright= process it earlier
  • Uses combined EEG and fMRI analysis to understand where things are happening in the brain and when they are happening
  • When processing faces = done in the STS part of brain
41
Q

How do we know where early visual processing and face processing occur in the brain?

A
  • From fMRI scans, we know that early visual processing occurs in the primary visual cortex right at the back of the brain
  • = can see clearly from scans
  • fMRI images= take images throughout height of the brain, can see that activity is strongest half way up = red
  • Each visual change = an event/stimulus onset
  • Neurons are responding to this stimulus onset, responding quickly
  • Left checkerboard= right hand brain at back
  • Electrodes w odd nos on the left, electrodes with even nos = on the right
  • If image on right hand screen= would see v strongly on left hemisphere at back of the head
    = observing the visual evoked potential
42
Q

Why is it hard to get brain signals?

A

Because of the noise= like needle in a haystack

- Need to filter out all other things the brain is doing to get cognitive process

43
Q

How many neurons are in 1 cubic mm of the brain?

A

1 million neurons in 1 cubic mm of

44
Q

Is everyone’s brain structure and brain functioning the same?

A

There are individual differences of structure and function- just as all our faces are different, all brains are different

45
Q

What influences the structure of the brain?

A

Experience, individual variability, genetics

46
Q

Are brains symmetrical?

A

Not entirely

47
Q

What types of individual differences can affect brain functioning?

A

The way we perform cognitive functions can vary from day to day e.g. influenced by strategy, mood, task difficulty

Cognitive (9 decks)

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