Ways of studying the brain - fMRI Flashcards
(29 cards)
What was the first method used to take images of brain structure?
CT scans
What were CT scans like at first and how did they work?
They used X-rays to take images of the brain structure and the detail was relatively poor but major abnormalities could be identified
What did CT scans get replaced by?
MRI Scans
What does CT stand for?
computed axial tomography
What does MRI stand for?
magnetic resonance imaging
How do MRI scans work?
It’s based on the magnetic properties of hydrogen atoms found in water in the brain. It uses a strong magnetic field and applies radio waves to produce high definition images of the brain
What does PET stand for?
positron emission tomography
When were PET scans introduced?
in the 1980s
How do PET scans work?
A radioactive substance (such as glucose) is injected into the bloodstream, it travels to the brain where the neurons use glucose to get energy and the most active brain regions accumulate more glucose and the radioactivity is picked up by the PET scanner
What are the issues with PET scans?
it’s invasive and prolonged
What are the four main ways to study the brain?
fMRI’s, EEG’s, ERP’s and post mortems
What does fMRI stand for?
functional magnetic resonance imaging
What is the principle behind fMRI’s and what was it developed from?
Developed from MRI’s and uses the principle that neurons most active during a task will use more energy, requiring glucose and oxygen to be carried in the bloodstream. This means blood flow to active areas of the brain should increase over control levels.
Oxygen is carried in the blood stream attached to molecules of haemoglobin in red blood cells. After oxygen is released for use by active neurons, haemoglobin becomes deoxygenated
What does fMRI indirectly measure?
blood flow, through the concentration of oxygen in the bloodstream
What is the signal used in fMRI called?
the BOLD contrast (Blood Oxygen Level Dependent)
What is an example of how are fMRI’s used in patients?
a participant may be asked to alternate between periods of doing tasks (looking at a stimulus for 30 seconds and then closing their eyes for 30 seconds) the fMRI can then be used to identify which parts of the brain are active during each task
What is an innovative and recently emerging application of fMRI?
It’s use in lie detection
What are fMRI’s important for understanding?
Brain localisation
What are the strengths of fMRI’?
+ It’s non invasive
+ They have good spatial resolution
How are fMRI’s non-invasive?
They are non-invasive as it doesn’t rely on the use of radiation and the patient just has to remain quiet and still in the scanner.
Why is the non-invasivity of fMRI’s a strength?
It is risk free so more patients can undertake the scans and this can help psychologists to gain further data on the functioning human brain and develop our understanding of localisation of function
What is spatial resolution?
The smallest feature (or measurement) that a scanner can detect
Why is a greater spatial resolution better?
It allows psychologists to discriminate between different brain regions with greater accuracy
What is the spatial resolution of fMRI’s and why is this important?
1-2mm, significantly greater than other techniques, this means psychologists can determine the activity of different brain regions with greater accuracy when using fMRI (compared to EEG and ERP)
