Human research methods Flashcards
1
Q
How is the brain studied?
A
- if want to know what an area of the brain is good for, find someone with brain damage in that area
2
Q
What is computerised tomography (CT) scan?
A
- cheap and fast
- resolution is not great
- computer assisted X-ray procedure
- take a “photograph” of the brain
3
Q
How does the CT scan work?
A
- X-ray beam (high energy light) is projected through the head to an X-ray detector
- beam delivered from all angles
- computer translates the information received from the X-ray detector into a series of pictures of the skull and brain
4
Q
What are the ways to photograph a living human brain?
A
- CT scan
- MRI
- DTI
- fMRI
- PET
5
Q
What is magnetic resonance imaging (MRI)?
A
- strong magnetic field and radio waves
- relative density of hydrogen atoms throughout the body
- high spatial resolution
6
Q
How does an MRI work?
A
- strong magnetic field is applied to the body
- the proton of every hydrogen atom in the body to orient in a particular direction
- radio waves (low energy light) are administered to the body
- energy is absorbed by protons, changing the direction they are facing
- each proton immediately flips back to the position determined by the magnet
- protons emit their own radio waves, which are detected by the scanner
- scanner provides an estimate of the relative density of hydrogen atoms throughout the body
7
Q
What is diffusion tensor imaging (DTI)?
A
- MRI can be optimized to better detect the hydrogen atoms in water molecules
- variation of the MRI technique
- measures the direction and speed of the diffusion of water molecules
- used to identify axon tracts
8
Q
What is functional magnetic resonance imaging (fMRI)?
A
- rapid series of MRI scans
- provides both structural and functional information
- decent spatial resolution (1 to 5 mm) and temporal resolution (several seconds)
9
Q
How does fMRI work?
A
- amount of oxygen in blood distorts the local magnetic field
- detect changes in blood oxygenation
- reflects blood flow and correlates with neural activity
- when brain area is active, blood flow to that region quickly increases
10
Q
Why are researchers trying to modify the fMRI technique?
A
- measure fluctuations in neurotransmitter signaling
- uses “enzyme-activated magnetic resonance contrast agents”
- molecules that distort the magnetic field differently when they bind to neurotransmitter
- create a molecule that distorts the magnetic field when bound to a neurotransmitter
11
Q
What is positron emission tomography (PET)?
A
- recording neural activity in human brain
- measure changes in the expression levels of neurotransmitter receptors across weeks (use radioactive drugs - agonists or antagonists)
12
Q
How does PET work?
A
- injecting a person with a radioactive compound
- radioactive sugar molecules (2-DG) used to detect changes in energy use in the brain
- scanner identifies where radioactive 2-DG molecules are located over time
- radioactive molecules are designed to decay rapidly (over hours), have to be made on site
13
Q
What is 2-DG?
A
- radioactive sugar molecules (injected in person during PET)
- similar to glucose
- taken up by active cells in the body
- not broken down as easily as sugar is, so it stays around for hours
14
Q
How does PET use L-Dopa?
A
- radioactive L-Dopa picked up by dopamine neurons
- converted into dopamine
- released as normal
15
Q
What are macroelectrodes?
A
- metal discs
- EEG uses macroelectrodes attached to scalp
- records the summed population-level activity of millions of neurons
- used as a diagnostic tool
- specific patterns of EEG activity are associated with different states of consciousness, stages of sleep, and types of cerebral atrophy
