Brains Scans and Quasi Experiments Flashcards
1
Q
why has it historically been difficult to look at the brain
A
- Historically you could only look at the brain post mortem
this is bad because: - can’t observe brain activity
- can’t see how it effects the individual’s behaviour
- can’t observe a healthy normal brain, like ours
2
Q
what are the 4 types of scans you need to know
A
- EEG
- CAT
- MRI
- PET
3
Q
what does each of the scans (EEG, CAT…) scan for + what do they stand for
A
- EEG (electroencephalogram) = brain function
- PET (Positron emission tomography) = brain function
- CAT (computed axial tomography) = brain structure
- MRI (magnetic resonance imaging) = brain structure
4
Q
what is temporal resolution
A
describes its ability to tell you exactly when the activation happened
5
Q
what is spatial resolution
A
Refers to the capacity a technique has to tell you exactly which area of the brain is active
6
Q
how does an EEG work
A
- in 1950s it was the only method for studying brain activity
- electrodes placed on scalp will record the electrical activity in regions of the brain
7
Q
how does a CAT scan work
A
- series of x-rays –> combining them to form an image (image is 2D but can also be 3D
- injecting a dye is sometimes used (helps highlights regions of the brain) –> creates a map of the brain’s structure
8
Q
how does an MRI scan work
A
- patient is placed inside a large circular magnet
- causes the hydrogen atoms in the body to move
- when the magnet is turned off = these revert to their original positions
- producing an electromagnetic signal that is translated by a computer into pictures of brain tissue
9
Q
how does a PET scan work
A
- patient injected with a radioactive tracker called FDG (fluorodeoxyglucose)
- after a period of time, patient is placed in a computer scanner
- positrons smash into electrons –> releasing gamma rays (which is picked up by the computer scanner)
- the detected emissions are plotted on varying levels of activity in the brain
- sometimes producing a 3D plot
10
Q
why is using an MRI scan better than a CAT
A
- gives more detailed image of soft tissue in the brain (because it involves passing an extremely strong magnetic field through the patient rather than using x-rays
- best suited for when patient undergoes several examinations consecutively because it won’t expose the patient to hazards of radiations
11
Q
why is using an MRI better than PET scans
A
- PET scans are less precise than MRI scans
- good when patient needs to go under examination several times = no injection required and no radiation exposure
12
Q
why is using a PET scan better than CAT scans
A
- reveals chemical information = can distinguish between malignant or benign tumours
- can also show the brain in action = useful for psychological research
13
Q
why is using a PET scan better than MRI
A
- reveals chemical information = can distinguish between malignant or benign tumours
- can also show the brain in action = useful for psychological research
14
Q
why is using CAT scans better than MRI scans
A
- cheaper = so is more readily available
- it also takes less time
15
Q
why is using CAT scans better than PET scans
A
- they provide structural information = can show tumours and structural damage in brain
