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2nd Year: Brain and Behaviour > Research methods > Flashcards

Research methods Flashcards

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1
Q

If brain function is localised, why is the idea of phrenology wrong?

A

Francis Gall thought that if you had larger brain areas you were better at certain things or had characteristic personality traits. This is not true, but different brain areas each control particular processes.

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2
Q

Define MRI.

A

Magnetic resonance imaging: used to visualise the brain.

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3
Q

How does MRI work? Give 4 main steps.

A
  1. Protons (the hydrogen atoms in the water of our bodies) have a property called spin.
  2. A magnetic field is applied that causes the protons to align.
  3. Bursts of radio frequency excite the protons so they move out of alignment.
  4. As they return to alignment they lose energy which is detected by a machine.
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4
Q

Define VBM.

A

Voxel based morphometry: a technique used to compare grey and white matter volumes.

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5
Q

What is a voxel?

A

A 3D pixel with a numerical value.

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6
Q

If a brain is divided into voxels what can it be interpreted as?

A

A mathematical matrix.

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7
Q

Give the 3 main steps in VBM.

A
  1. Spatial normalisation of the brain
  2. The image is segmented to remove the skull from the image
  3. The image is smoothed to ‘average out the noise’ and normalise the images. This is the equivalent of creating percentages, it takes into account different starting points.
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8
Q

Give an example of a famous study using VBM.

A

The comparison of London taxi and bus drivers. Was hypothesised that taxi drivers would have more grey matter due to an enlarged hippocampus as they need to remember way more routes than bus drivers. This was found to be true. Was also found that grey matter volumes varied within taxi drivers - those with more years of experience had more.

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9
Q

What is an advantage of VBM?

A

It is automated.

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10
Q

A disadvantage of VBM is that it gives us no information about what causes changes in white/grey matter volumes, or about cognition. True or false?

A

True.

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11
Q

Define DTI, also called DWI.

A

Diffusion tensor/weighted imaging: a technique that uses the restricted diffusion of water to help visualise the neural tracts.

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12
Q

A disadvantage of DT/WI is that it gives us no information about what causes changes in neural tracts, or about cognition. True or false?

A

True.

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13
Q

Define track tracing.

A

The injection of chemicals or proteins into neurons that can be traced to help visualise neuronal networks/synapses.

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14
Q

In track tracing experiments animals are kept alive. True or false?

A

False - animals are euthanized shortly after injection and preserved with formaldehyde.

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15
Q

What is an advantage of track tracing?

A

It has a very fine resolution so is better than other techniques like DTI. Allows us to actually visualise how brain areas are connected.

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16
Q

What is a disadvantage of track tracing?

A

It cannot be done in live animals thus only produces a ‘frozen image’. It does not allow us to view live processes like learning or memory.

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17
Q

Define immunohistochemistry.

A

The brain is finely sliced and bathed in antibodies that bind to specific target cells.

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18
Q

What does immunohistochemistry allow us to do?

A

Visualise bound antibodies, which are usually stained with dyes, in order to look at whole neurons or synapses.

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19
Q

Why did the brain need to be sliced in immunohistochemistry?

A

Because of the myelin sheath.

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20
Q

The brain no longer needs to be sliced in immunohistochemistry. Why?

A

Scientists have found a way of replacing it with transparent matrices so it no longer effects visualisation.

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21
Q

What is the advantage to not slicing the brain in immunohistochemistry?

A

Neurons and synapses are much better preserved.

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22
Q

What is an advantage of immunohistochemistry?

A

Antibodies are very specific, allowing us to focus on particular neurons.

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23
Q

What are 2 disadvantages of immunohistochemistry?

A
  1. Cannot be done in live animals so we cannot visualise dynamic processes like learning
  2. We do not have ABs for all cell types in le brain
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24
Q

Define (human) neuropsychology.

A

Examining patients with brain damage to assess cognitive impairment and the brain areas involved.

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25
Q

The discovery of Broca’s areas is an example of neuropsychology. What did it determine about Broca’s area?

A

That it was involved in speech, showing the left frontal lobe to be involved with language.

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26
Q

Unilateral temporal lobectomy is the removal of one of the temporal lobes. What happens when the right lobe is removed?

A

Creates hemispatial neglect: a deficit in attention and awareness of one side of space is observed.

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27
Q

What is a patient with hemispatial neglect unable to do?

A

Perceive or respond to stimuli on one side of the body.

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28
Q

If hemispatial neglect only arises from damage/loss of the right hemisphere, which side of the body is no longer able to perceive stimuli?

A

The left side.

29
Q

Unilateral temporal lobectomy is the removal of one of the temporal lobes. What happens when the left lobe is removed?

A

Episodic memory is impaired.

30
Q

Define episodic memory.

A

The memory of events.

31
Q

What is an advantage of neuropsychology?

A

It shows you which brain regions are necessary for certain functions.

32
Q

What are 3 disadvantages of neuropsychology?

A
  1. Lesions are never selective as it is immoral to create lesions in patients, you can only study ones that are already there.
  2. Due to neuroplasticity the brain can compensate for the effects of lesions
  3. You cannot study the processes within/interactions between regions
33
Q

How can we create lesions in the brains of animals? Give 2 methods.

A
  1. Surgery

2. The administration of excitotoxic chemicals

34
Q

Define an excitotoxic chemical.

A

One that causes nerve cell bodies to over-excite and as a result degrade.

35
Q

What are the 2 main advantages of studying lesions in animals?

A
  1. Lesions are precise

2. Experiments are repeatable and can be controlled

36
Q

What is a major disadvantage of animal lesion studies?

A

You cannot ask the animal how it is feeling.

37
Q

We can genetically modify the brain. What do gene deletions do?

A

These are mostly fatal.

38
Q

We can genetically modify the brain. What are ‘knock-down’ experiments?

A

Where gene expression is greatly reduced.

39
Q

We can genetically modify the brain. What are ‘conditional knock-out’ experiments?

A

The gene is only silenced under specific conditions, e.g. in the presence of a particular chemical.

40
Q

We can genetically modify the brain. What are ‘inducible knock-out’ experiments?

A

Whereby genes are only silenced when drugs are applied.

41
Q

We can genetically modify the brain. What are ‘knock-in’ experiments?

A

Where new genes are introduced.

42
Q

Define optogenetics.

A

The control of nervous responses with light.

43
Q

Explain how optogenetics works.

A
  1. Channel rhodopsin opens a channel when exposed to photons

2. This causes excitation of the neuron, creating an AP

44
Q

What is halorhodopsin?

A

The inhibitory equivalent of channel rhodopsin.

45
Q

Define TMS.

A

Transcranial magnetic stimulation: a non-invasive method whereby a coil is placed over the head and stimulates the brain via electromagnetic induction.

46
Q

What is TMS used to measure?

A

The connectivity between the brain and muscles.

47
Q

What is tDCS?

A

Transcranial direct current stimulation: a low current is delivered to areas of interest via small electrodes attached to the skull.

48
Q

What has tDCS been found to improve in healthy adults?

A

Cognitive function.

49
Q

What is DBS?

A

Deep brain stimulation: a highly invasive treatment for brain disease, not used in experimental psychology.

50
Q

What is fMRI?

A

Functional magnetic resonance imaging: a form of MRI that measures deoxyhaemoglobin in the blood.

51
Q

How does fMRI allow us to see which brain areas are active during particular functions?

A

In active brain areas there is oxygenated blood as the tissues are respiring more.

52
Q

How does fMRI help to detect cancer?

A

Tumours requires much oxygen to grow, thus oxygenated areas are indicative.

53
Q

fMRI produces a BOLD signal. What does this stand for?

A

A Blood Oxygenation Level Dependent signal.

54
Q

Define magnetoencephalography.

A

The use of equipment to detect the net electromagnetic activity in neurons to see which brain areas are excited.

55
Q

What causes electromagnetic activity in neurons?

A

Ion flow.

56
Q

Define electroencephalography.

A

Measures electrical activity through the scalp.

57
Q

What causes electrical activity in the brain?

A

The conduction of APs.

58
Q

Why can we not properly examine brain activity during movement?

A

Most imaging techniques require cumbersome and complex equipment.

59
Q

What does fNIRS stand for?

A

Functional near-infrared spectroscopy

60
Q

Explain how fNIRS works?

A

An appropriate wavelength of light is selected under which tissue like skin and bone are mostly transparent but haemoglobin and deoxyhaemoglobin have different absorbance rates.

61
Q

What is the point of fNIRS?

A

To see which parts of the brain are actively respiring and thus being used.

62
Q

Under which wavelength of light is tissue transparent?

A

700-900nm

63
Q

Explain how calcium imaging works.

A

Cytosolic Ca2+ is recorded with a fluorescent recorder

64
Q

What is the point of calcium imaging?

A

Can use it to image whole neurons by tracing the Ca2+ paths. Can also deduce ‘synaptic partners’.

65
Q

What is a single-unit recording?

A

Looks at the firing of single neurons using a single electrode

66
Q

What is a multiple-unit recording?

A

Uses an electrode that can measure between 50-100 neurons at once. Looks like a spiky plate. Can be used to look at neurons individually or together.

67
Q

What happens in microdialysis?

A
  1. A small hole is bored into the skull.
  2. A cannula is inserted and filled with fluid
  3. Substances in the ECF of neurons diffuse through the dialysis tubing
  4. The fluid is collected and analysed
68
Q

Give an example of an experiment using microdialysis.

A

A probe was inserted into the ventral tegmental area to assess the active NTs in the nucleus accumbens pathway. Adjacent brain areas are stimulated to see how this affects the chemical balance.

2nd Year: Brain and Behaviour (20 decks)

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