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PSYC 211 > Lecture 8: Research Methods > Flashcards

Lecture 8: Research Methods Flashcards

1
Q

how does a CT Scan work?

A

High-energy electromagnetic radiation is delivered to the head from all angles. A computer translates the information received from the X-ray detector into a series of pictures of the skull of the brain

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2
Q

advantages & disadvantages of a CT scan

A

advantages: cheap and fast
disadvantages: the resolution is not great for soft tissue like the brain

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3
Q

how do MRIs work?

A
  • A strong magnetic field is applied to the body,
  • the spin of every hydrogen atom (proton) assumes a particular direction in line with the magnetic field
  • Radiofrequency waves are administered to the body
  • The energy is absorbed by protons, changing the direction of their spin
  • Protons then emit their radio waves when their spin flips back to that determined magnet
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4
Q

the MRI can estimate ____

A

the relative density of protons in each area of the body

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5
Q

there are more protons in

A

fat and water

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6
Q

MRIS can be optimized to detect

A

the hydrogen atoms in water molecules

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7
Q

how does diffusion tensor imaging (DTI) work?

A

measures the direction and speed of the diffusion of water molecules by taking several pictures in rapid succession

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8
Q

DTI is used to identify ___

A

axon tracts

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9
Q

how does Functional Magnetic Resonance Imaging (fMRI) work?

A

infers the movement of oxygenated blood around the brain by collecting a rapid series of MRI scans and measuring the movement of these magnetic field distortions over time. goal = measure brain activity during behaviour

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10
Q

how does Positron Emissions Tomography (PET) work?

A

injects a person with a radioactive compound (ex. 2-DG) to detect changes in energy use in the brain. identifies where radioactive molecules are located over time & measures the changes in expression levels of neurotransmitter receptors.

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11
Q

disadvantage of PET scans

A

operating costs (2-DG has to be made on-site the morning fo the experiment because it decays so quickly)

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12
Q

what are macroelectrodes?

A

metal discs attached to the scalp to record the summed population-level activity of millions of neurons on cortical surfaces

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13
Q

diagnosis & EEGs

A

macroelectrodes and EEGs can be used as diagnostic tools since specific patterns of EEG activity are associated with different states of consciousness, sleep, and type of cerebral atrophy

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14
Q

experimental ablation

A

Involves the removal or destruction of a portion of the brain

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15
Q

radiofrequency lesions

A

destruction of a brain region. burning a part of the brain with low-energy radiation.

Small lesions made by passing a radiofrequency current through a metal wire that is insulated everywhere but the tip.This electric current produces heat that burns cells around the tip of the wire

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16
Q

how are the size and shape of radiofrequency lesions determined?

A

the duration and intensity of the current

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17
Q

the downside of radiofrequency lesions

A

axons & cell bodies just passing through will also be burned

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18
Q

excitotoxic lesions

A

destruction of a brain region. lesions produced by intracerebral injection of a glutamate receptor agonist, such as kainic acid. causes cause so much calcium influx that the affected neurons undergo apoptosis

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19
Q

advantage of excitotoxic lesions

A

axons passing through are usually spared

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20
Q

sham lesion

A

Placebo procedure that duplicates all steps of producing brain lesions except for one that causes extensive brain damage

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21
Q

reversible lesions

A

Temporary brain lesions achieved by injecting drugs that block or reduce neural activity in a given region

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22
Q

common drugs for reversible lesions include

A

voltage-gated sodium channel blockers and GABA receptor agonists

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23
Q

voltage-gated sodium channel blockers

A

stop all action potentials

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24
Q

GABA receptor agonists

A

hyperpolarize cell bodies

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25
Q

microelectrodes

A

Thin metal wires with a fine tip that can record the electrical activity of individual neurons (called a single-unit recording)

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26
Q

new microelectrodes can

A

record the activity of hundreds of neurons simultaneously

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27
Q

chronic electrical recordings

A

electrical recordings made over an extended period of time

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28
Q

acute recordings

A

made over a relatively short period (often after surgery)

29
Q

electrical stimulation

A

involves passing an electrical current through a wire inserted into the brain

30
Q

high-frequency electrical stimulation patterns ___

A

tend to produce the same behavioural effects as lesioning the brain area

31
Q

chemical stimulation

A

Drugs are administered through a guide cannula (hollow tube) implanted in a particular brain region

32
Q

optogenetics

A

The use of light to control neurons which have been made sensitive to light through the instruction of foreign DNA

33
Q

opsins

A

light-sensitive ion channels

34
Q

excitatory opsins

A

you can either pulse light or leave it on to drive action potential activity

35
Q

inhibitory opsins

A

continuous light pulses can be used to inhibit action potential activity

36
Q

excitatory opsin example

A

ChR2

37
Q

inhibitory opsin example

A

halorhodopsin

38
Q

virus

A

A small infectious agent that replicates inside the cells of other organisms
The DNA of a virus encodes instructions on how to make more virus

39
Q

virus-mediated gene delivery

A

adding foreign DNA to the virus that encodes things like optogenetic proteins. when a modified virus is injected into an animal’s brain, it infects the cells it comes into contact with. Once the virus gets its DNA into the infected cell’s nucleus, that cell will start to transcribe it and make the foreign protein

40
Q

we can target opsin expression to specific neurons according to

A
  1. where their soma is located
  2. where their axons are located
  3. the proteins they express
  4. whether they recently had more action potentials than normal
41
Q

fluorescent calcium imagining

A

records neural activity from specific genetically-defined neurons. Green fluorescent protein (GFP) is modified into GCaMP, allowing it to bind to calcium and fluoresce much brighter when it does.
Since a calcium influx occurs during action potentials, monitoring GCaMP fluorescence is a good way to measure neural activity

42
Q

retrograde labelling

A

tracing afferent axons

43
Q

anterograde labelling

A

tracing efferent axons

44
Q

retrograde tracers example

A

flurogold

45
Q

anterograde tracers example

A

PHA-L

46
Q

stereotaxic surgery

A

uses a stereotaxic apparatus to inject and permanently implant things into the brain

47
Q

bregma

A

the junction where pieces of the skull fuse together. often used as a reference point for stereotaxic surgery

48
Q

reasons for sterotaxic surgery

A
  • lesion a brain area
  • lesion a specific type of cell
  • change gene expression
  • implant guide cannula
  • implant microelectrodes
  • implant fibre optic cables
49
Q

guide cannula

A

hollow tube

50
Q

microdialysis

A

the use of a semipermeable membrane to either deliver molecules or measure the number of molecules in some solution or brain area

51
Q

microdialysis probe

A

small metal tube that holds dialysis tubing. these can be placed in the animal’s head

52
Q

fastest sampling rate for molecules to equilibrate across a dialysis membrane

A

once per minute

53
Q

typical sampling rate for molecules to equilibrate across a dialysis membrane

A

once per 10 mins

54
Q

only serotonin neurons express ___

A

serotonin reuptake proteins

55
Q

only glutamate neurons express ___

A

vesicular gluatamate transporter proteins

56
Q

immunohistochemistry

A

a histological method that is used to label proteins and peptides of biological tissue. when fluorescent antibodies that selectively bind to different types of proteins are washed over a brain slice, the brain slice of interest becomes fluorescently labelled

57
Q

t or f: it is easy to make an antibody that selectively binds to a small molecule such as a classic neurotransmitter

A

false; it is impossible

58
Q

t or f: it is easy to make an antibody that binds to a specific protein

A

true

59
Q

antibodies

A

proteins made by the immune system of mammals.

60
Q

advantages of fMRIs

A

they are not invasive & provide structural and functional information with decent spatial & temporal resolution

61
Q

do recpetor agonists & antagonists affect axons passing through the area

A

no

62
Q

what do anesthetics do to neural activity?

A

shut it down

63
Q

how do researchers identify cells that make and release classical neurotransmitters?

A

using antibodies against the enzymes that make these neurotransmitters

64
Q

the downside of excitotoxic lesions

A

animals can’t serve as their own controls; sham lesions are needed

65
Q

advantage of chemical stimulation

A

animals can serve as their own controls

66
Q

neuronal projection

A

Function: map axonal projections in the brain
Method: inject fluorescent molecules

67
Q

2 types of neuronal projection

A

retrograde & anterograde labelling

68
Q

immunohistochemistry disadvantage

A

can’t localize small molecules like classical neurotransmitters

PSYC 211 (23 decks)

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