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Neuroscience and Behaviour > Neuroscience > Flashcards

Neuroscience Flashcards

1
Q

What is cytoarchitectonics?

A

A method of segmenting the brain into areas based on the microscopic appearance of cell types and layers.

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2
Q

What are Brodmann areas?

A

Numbered brain areas defined by Brodmann based on cytoarchitectonics and comparative neuroanatomy.

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3
Q

How does Transcranial Magnetic Stimulation (TMS) work?

A

A magnetic field generated by a coil induces an electric field in the brain, exciting neurons.

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4
Q

What are the main applications of TMS?

A

EEG records ongoing brain electrical activity, while ERPs are EEG signals averaged and time-locked to specific events.

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5
Q

Distinguish between exogenous and endogenous ERPs.

A

Exogenous ERPs are automatic responses driven by physical stimulus properties, while endogenous ERPs reflect cognitive processes like attention and expectation.

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6
Q

What is the purpose of cytoarchitectonics?

A

To segment the brain into areas based on the microscopic appearance of cell types and layers (cytoarchitecture).

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7
Q

Who pioneered the cytoarchitectonic mapping of the brain?

A

Korbinian Brodmann in the early 1900s, defining numbered Brodmann areas.

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8
Q

What does a wide layer V indicate about a cortical area?

A

A wide layer V suggests the area is involved in output processing, sending signals from the brain to the periphery.

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9
Q

What does a wide layer IV indicate?

A

A wide layer IV suggests the area is involved in input processing, receiving signals from the periphery.

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10
Q

What is the basic principle behind TMS?

A

Creating temporary virtual lesions, studying chronometry of brain activation, and assessing functional connectivity.

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11
Q

What are the main applications of TMS?

A

Creating temporary virtual lesions, studying chronometry of brain activation, and assessing functional connectivity.

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12
Q

How are TMS effects measured for motor cortex stimulation?

A

By observing muscle twitches corresponding to the somatotopic map of the motor cortex.

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13
Q

What is a key advantage of TMS over patient lesion studies?

A

TMS allows studying virtual lesions in healthy participants with better experimental control.

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14
Q

What is the EEG measuring?

A

The electrical activity generated by neurons in the brain, recorded from electrodes on the scalp.

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15
Q

How are ERPs derived from the EEG?

A

By averaging EEG segments time-locked to specific events of interest to extract the event-related signal.

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16
Q

What are exogenous ERPs?

A

ERPs directly driven by physical properties of the stimulus, like the auditory N1 response.

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17
Q

Give an example of an endogenous ERP component.

A

The P300 or P3 component, elicited in response to infrequent or unexpected events.

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18
Q

What is the contingent negative variation (CNV)?

A

A negative ERP reflecting anticipation and preparation between a warning stimulus and an imperative stimulus.

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19
Q

List the following in order of temporal resolution – EEG, fMRI, MEG ERP, and MRI

A

MEG, ERP, EEG, fMRI, MRI

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20
Q

Which has better spatial resolution? EEG or fMRI? fMRI

A

fMRI

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21
Q

What is an advantage of EEG compared with fMRI?

A

What is an advantage of EEG compared with fMRI? Better temporal resolution – well-suited to transient events such as the onset of stimuli. Whereas with fMRI there is a time lapse between brain activity and the movement of blood which limits the speed at which you can perform experiments

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22
Q

Is MRI structural or functional? Why?

A

Structural – compares the behaviour of charged Hydrogen ions in relation to fat and water content in different brain areas.

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23
Q

Which are Brodmann’s areas 7, 4, 1,2,3 and 41?

A

7 = Primary Visual Cortex, 4 = Primary motor cortex, 1,2,3 = Primary Somatosensory Cortex, 41 = Primary Auditory Cortex

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24
Q

What assumption did Brodmann make?

A

6 cortical layers – 4 = input, 5&6 = output

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25
Q

In the PMC, which cortical layer is notably wide?

A

4 (input)

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26
Q

In the PSC, which cortical layer is notably wide?

A

5 (output)

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27
Q

How does transcranial magnetic stimulation work?

A

Device placed against head => brief pulse => magnetic coil forms a magnetic field with perpendicular flux lines => activates cortical cells trans-synaptically.

28
Q

What is the temporal resolution of TMS? Ms

A

Ms

29
Q

What are some key weaknesses of TMS?

A
  1. Can only measure 1 point at once
  2. Auditory stimuli hard to measure due to loud coil click
30
Q

How many mm lateral from the vortex should you place the TMS coil in order to trigger a response to the thumb?

A

5mm

31
Q

How long does it take for a contracted vs relaxed muscle to respond to TMS?

A

150 vs 20ms

32
Q

What are motor neuroelectrical signals measured in (TMS)

A

Motor EP’s

33
Q

What are visual neuroelectrical signals measured in? (TMS)

A

Phosphemes

34
Q

What has TMS shown re. early blind individuals, describe 2 study designs

A

Cross-modal plasticity – use the visual cortex to read braille, as shown in an ISI design (20ms for occipital cortex response vs 50-80ms for a SSC response) and a virtual lesion design (blind participants struggled to read braille when lesion was to the occipital cortex whereas control struggled more when lesion was to the somatosensory cortex).

35
Q

What are some key advantages of TMS?

A
  1. Ms temporal resolution
  2. Can repeat studies
  3. Group studies can be standardised
  4. Can study double dissociations
  5. Virtual lesions may be better defined than real lesions
36
Q

True or false? fMRI induces interference whereas EEG and TMS show correlation between activation and cognitive event

A

False, TMS induces interference, the others show correlation

37
Q

What is the term for the simplest synchronous activation in EEG?

A

Dipoles

38
Q

Biophysical basis of EEG

A

Cortical neurons generate dipoles under the influence of post-synaptic potentials (i.e. mini electric currents produced by NT release => change in electric field).

39
Q

Describe the Berger effect:

A

Biophysical basis of EEG Cortical neurons generate dipoles under the influence of post-synaptic potentials (i.e. mini electric currents produced by NT release => change in electric field).

40
Q

What is the difference between spontaneous and continuous oscillations?

A

Spontaneous = ongoing, intrinsic activity. Continuous oscillations tend to occur in response to external inputs/specific cognitive processes.

41
Q

Which oscillations are 3-7 Hz?

A

Theta

42
Q

What are the two types of electrophysiological signals produced in EEG? + what do they measure?

A

EROs (frequency) and ERPs (voltage)

43
Q

Complete the blank? ERP’s are defined in _____ to an _____

A

Latency, event

44
Q

Thut et al. 2016

A

Visualspatial attention task – had to pay attention to stimuli on one side of a screen. Found decreased alpha activity when ppts had been given a cue and were waiting for a target. Strongest for R motion @ L electrodes and vice versa.

45
Q

What are the 2 prerequisites of ERP?

A

1) Neurons are active in synchrony
2) Electric fields are oriented so they cumulate spatially

46
Q

Exogenous vs endogenous ERP’s?

A

Exogenous = auto responses controlled by physical properties of a stimulus e.g. auditory.
Endogenous = interaction between subject and event e.g. attention, task relevance & expectations

47
Q

What are key weaknesses of ERP’s?

A
  1. Source localisation i.e. lateral areas harder to pinpoint than front/central areas
  2. scalp smears the readings
  3. topography depends on reference electrode placement
48
Q

Describe Mismatch Negativity and how it is different in schizophrenic / dyslexic individuals

A

MMN = ERP component elicited by ‘deviant tone’ in passive auditory oddball paradigm. Larger deviance = larger MMN. Sz = reduced MMN, stronger for duration than freq. Dyslexia = reduced amp correlated with dyslexia severity.

49
Q

What is the basis of MRI?

A
  1. Hydrogen ions are charged
  2. Body is 70% water
  3. Can align the magnetic fields of H ions with big magnet
  4. Then use 3 RF coils to manipulate the magnetic field
  5. Time how long it takes to return to the equilibrium state
50
Q

T1 vs T2

A

T1 = spin lattice. Resolution along Z axis. Good for fat vs water.
T2 = spin spin. Relaxation due to transverse magnetisation decays i.e. component of magnetisation perpendicular to main magnetic field. T2 measured as time for 63% of transverse magnetisation to be lost. Faster for water tissues.

51
Q

What does the fMRI BOLD signal measure?

A

Blood oxygen

52
Q

How does fMRI work?

A
  1. Blood oxygen has weak negative magnetic susceptibility
  2. Activity => oxygenation => increased homogenous magnetic field => longer T2 relaxation time
53
Q

Oxygenated vs deoxygenated magnetic properties

A

Oxygenated = diamagnetic
Deoxygenated = paramagnetic

54
Q

THE key weakness of fMRI

A

Time delay between stimulus & BOLD signal is huge relative to the speed of sensory and cognitive processes

55
Q

2 types of fMRI experiments?

A
  1. Block designs (overlapping trials, stimuli must be the same) – more robust/statistically reliable but less flexible
  2. Rapid event-related design (baso random firing of different types of stimuli. We’ll sort it out later approach) – avoids habituation but less sensitive to neural events
56
Q

What 3 steps need to be carried out post-signal collection?

A
  1. Motion correction (realign images)
  2. Coregistration between functional and anatomical scans (superimpose functional onto spatial maps to improve spatial resolution)
  3. Normalisation to allow for intra-individual comparisons (multiple ppts can be aligned)
57
Q

Example of a brain atlas/co-ord system?

A

Talairach-Touronoux – not v precise but well standardised

58
Q

How to quantify MR signals?

A
  1. Compare predicted and observed timecourses of activation
  2. How closely they align = correlation
  3. Run a GLM to establish correlation
59
Q

Which neuroimaging method has a high chance of type 1 error?

A

fMRI

60
Q

3 examples of hemi-spatial neglect tasks?

A
  1. Albert task (cross out lines below dots)
  2. Line bisection task
  3. Drawing/copying task
61
Q

Which brain area is associated with hemispatial neglect?

A

Temporo-parietal junction

62
Q

Do lesions necessarily equate to brain damage in the identified region? Why?

A

No – could also affect relay stations, instead of the functional region itself

63
Q

Association vs dissociation

A

Association = damage to a single region => multiple deficits
Dissociation = task A impaired but task B remains the same

64
Q

Example association lesion – symptoms and affected brain region

A

Balint’s syndrome – associated with the parieto-occipital cortex
1. Simultanagnosia - 1 object at a time
2. Oculomotor apraxia – irregular eye movements
3. Ocular ataxia – difficulty reaching for objects

65
Q

Example dissociation lesion – symptoms and affected area

A

Visual form agnosia - Ventro-lateral lesion
- Letterbox task fine
- Couldn’t describe whether horizontal or vertical
Suggests recognition impaired but movement fine

66
Q

Double dissociations example (visual)

A

Extrasiate visual areas have 2 pathways – occipital-temporal and occipital parietal. Mirrored by M cells => parietal cortex and P cells => temporal

67
Q

Double dissociations example (Frontal lobe lesion)

A

FL lesion on right side implicated memory for designs whereas on left side implicated memory for words – suggests hemifield specialisation

Neuroscience and Behaviour (12 decks)

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