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PSYC211 > Methods and streategies of research > Flashcards

Methods and streategies of research Flashcards

1
Q

What are the different methods of imaging used on humans?

A
  • CT
  • MRI
  • fMRI
  • DTI
  • PET
  • Macroelectrode EEG
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2
Q

What is the purpose of CT scans?

A

Structure

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3
Q

How does a CT scan function?

A
  • With X-Rays
  • X-Rays allow to measure the density of the tissue and get a general idea
  • a computer uses the info to generate a series of “photographs” of the brain
  • the X-Rays are sent from all around the brain
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4
Q

What is the purpose of an MRI scan?

A

Structure

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5
Q

What are the three main purposes of the study of the brain?

A
  • understand structure
  • understand correlation
  • understand causality
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6
Q

What is the concept of an MRI?

A
  • uses strong magnetic fields and radiofrequency waves
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7
Q

How does an MRI function?

A
  • the spin of all hydrogen atom proton assume a particular definition inline with the magnetic field
  • the radiofrequency waves administered to the body change the direction of the spin
  • the protons emit radio waves when their spin flips back to the one determined by the magnet
  • map of the radio waves is emitted
  • provides an estimate of the density of the protons and allows to map the hydrogen atoms, which are present in lipids, which allows to map the imagery of the brain
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8
Q

What type of mapping does an MRI allow?

A
  • A mapping of the lipids in the brain
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9
Q

What is a DTI?

A
  • a specially calibrated MRI
  • allows to measure the direction and speed of the diffusion of water molecules
  • water flows around the axons in the brain
  • used to identify axon tracts
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10
Q

What is an fMRI?

A
  • subtype of MRI
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11
Q

What is the purpose of an fMRI?

A
  • maps neural activity in the brain
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12
Q

How does an fMRI function?

A
  • maps the amount of oxygenated blood in every region of the brain (more oxygenated blood=more activity)
  • hemoglobine protein transports the blood and it has an iron atom.
  • the magnetic field is distorted by the presence of iron
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13
Q

What is the purpose of a PET scan?

A
  • evaluating correlation
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14
Q

How does a PET scan function?

A
  • injection of radioactive compounds
  • can measure the radio-activity and positrons coming out of the body
  • can map out where the radio-activity is coming from
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15
Q

Why are PET-scans so cool?

A

You can make anything radioactive!

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16
Q

What does a macroelectrode measure?

A

the electrical activity in the brain (correlation)

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17
Q

How does a macroelectrode function?

A
  • metal discs are attached to the scalp
  • records the activity of neurons
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18
Q

What is an experimental ablation?

A
  • removal or destruction of a part of the brain
  • function that can no longer be performed after the surgery: the ones that region of the brain normally controls
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19
Q

What are the different types of lesion experimental ablations?

A
  • radiofrequency lesions
  • excitotoxic lesion
  • sham lesion
  • versible lesion
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20
Q

What are radiofrequency lesions?

A
  • small lesions made by passing radiofrequency current through a metal wire
  • heat burns the cells
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21
Q

What is the problem with radiofrequency lesions?

A
  • in inserting the metal rod, the axons are damaged.
  • in the burning of a specific region, the axons that are just passing through are also damaged
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22
Q

What is an excitotoxic lesion?

A
  • injection of a glutamate receptor agonist
  • cells are too stimulated: causes apoptosis
  • axons that pass through are spared
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23
Q

What is a reversible lesion?

A
  • injection of drugs that block or reduce neural activity in a given region
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24
Q

What is a sham lesion?

A
  • placebo procedure: duplicates all steps of producting brain lesions, except for the one that causes extensive brain damage
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25
Q

What are micro-electrodes?

A
  • thin metal wires that can record the electrical activity of specific individual neurons
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26
Q

What is stereotaxic surgery?

A
  • the surgery necessary for implanting micro-electrodes in the brain of animals
27
Q

What are the advantages of using micro-electrodes?

A
  • the rats always have the electrode
  • you can plug them in at any time
  • the rats can have other types of behaviors and activities and can just live their life while you map out the activity of their neurons
28
Q

What are the two types of micro-electrode reading?

A
  • acute (only during a short period of time)
  • chronic (made over an extended period of time)
29
Q

What is neuronal tracing?

A
  • inject a molecul to stain pre or post synaptic neurons, in order to track action potentials
30
Q

What is retrograde neuronal tracing?

A

Allows to trace the afferents of the cell of interest

31
Q

What is the chemical used in retrograde neuronal tracing?

A

fluorogold

32
Q

What is the chemical used in anterograde neuronal tracing?

A

PHA-L

33
Q

What is anterograde chemical tracing?

A

Allows to trace the efferents of the cell of interest

34
Q

What are the different methods used to manipulate neural activity?

A
  • electrical stimulation
  • chemical stimulation
  • optogenetics
35
Q

What is electrical stimulation?

A
  • passing an electrical current through a wire inserted into the brain
36
Q

What is chemical stimulation?

A
  • administration of drugs, directly into the brain, via a guide canula, implanted in a particular brain region
37
Q

What is optogenetics?

A
  • use of light to control neurons which have been made sensitive to light through the introduction of foreign DNA
38
Q

What are opsins?

A

light-sensitive proteins

39
Q

What are the opsins used for optogenetics?

A

light-gated ion channels,

40
Q

How do optogenetics work?

A
  • a gene for a light-sensitive protein is extracted from algae, then inserted into a specific neuron in the brain.
  • you can now cause the modified neurons to activate or inhibit action potential activity
41
Q

How is the DNA of the neurons manipulated in order to make them photo-sensitive?

A

Through viral-mediated gene delivery

42
Q

What is viral-mediated gene delivery?

A
  • extract the dna from a virus
  • add in the virus the dna we wish to code
  • the virus is injeted in the brain
  • the virus infects the cell it comes in contact with
  • the cell starts transcribing the new DNA and makes the foreign protein
43
Q

How can opsins be targeted?

A
  • according to where the soma is located
  • according to where the axons are located
  • according to the proteins that are expressed by the neurons
  • according to wheter or not the neuron has recently had more action potential than normal
44
Q

What can you measure by using electrical stimulation?

A

Behavioral effects

45
Q

What can you measure by using pharmacological manipulation?

A

behavioral effects

46
Q

How can you specify exactly which neurons or type of cells should express the foreign DNA that is in a virus?

A

By coding a promoter for a specific cell type before

47
Q

What does optogenetics allow to measure?

A

Behavioral effects

48
Q

What is fluorescent calcium imaging?

A
  • technique where there is a protein that fluoresces when bound to calcium that is injected/artificially coded in the brain
  • whenever there is an AP, there is calcium that enters the cell. therefore, there is a fluorescence
  • need stereotaxic surgery to implant a fiber optic cable
49
Q

How can you observe the traced neural connections?

A
  • opening the brain
50
Q

What is stereotaxic surgery?

A
  • surgical intervention that uses a stereotaxic apparatus
  • device that permits a surgeon to put something into a very specific part of the brain
51
Q

What are stereotaxic apparati used for?

A

injecting elements into the brain or implementing permanent elements (cannula, electrodes, fiber optic cable)

52
Q

What is the bregma?

A
  • the junctions where pieces of skull fuse together
53
Q

What are some common reasons for stereotaxic surgery?

A
  • injection of drug or virus
  • implant guide cannula
  • implant microelectrodes (stimulation/recording experiments)
  • implant fiber optic cables (imaging/stimulation using optogenetic techniques)
54
Q

What are brain injections used for?

A
  • lesion a brain area
  • lesion a specific type of cell
  • change gene expression
55
Q

How can you measure neurotransmitter levels in a being?

A

microdialysis

56
Q

What is microdyalisis?

A

use of a semi-permeable membrane to measure the amount of molecules in some solution/brain area.
take a sample of extracellular fluid and measure different concentrations

57
Q

What is a micro-dyalisis probe?

A

small metal tube that holds dialysis tubing

58
Q

What is himmunohistochemistry?

A

use of fluorescent antibodies
when washed over a brain slice, they will make the proteins of interest fluorescently labeled
with a microscope, you are now able to identify which cells contain these proteins

59
Q

What is himmunohistochemistry mostly used for?

A
  • identifying protein expression patterns
  • can indicate where neurotransmitters are released and what receptors are there
60
Q

what do researchers do when they are unable to create an antibody that will bind directly to the molecule of interest?

A
  • create an antibody of a cell or protein that is necessarily used with the compound of interest or that is a precursor to the molecule of interest (dopamine and enzymes)
61
Q

What are immediate early genes?

A
  • genes that tend to be expressed following periods of elevated spiking activity
62
Q

What is cFOS?

A
  • immediate early gene
  • level of cFOS elevates in the cell bodies of neurons when there is a spike in activity
63
Q

How can we use cFOS?

A

levels can be measured in brain slices using immunohistochemistry to determine which neurons were used one or two hours before the animal’s death

PSYC211 (21 decks)

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