Using Scanning to Study the Brain Flashcards
Why do we use brain scans?
Helps understand the relationship between different parts of the brain and their functions; helps locate affected areas in the brain by neurological disorders and devise new strategies of scanning for treatment
How is the procedure similar for all types of scans?
The individual lies down in the scanner, as still as possible, whilst detectors circle their heads, obtaining information about one ‘thin slice’ of brain at a time
How is ‘thin slices’ produced by brain scans useful?
Using multiple “slices”, we can build up a 3D image of the brain
define spatial resolution
how much fine detail is presented in the scan image
Why is spatial resolution good?
high spatial resolution shows more detailed images
define temporal resolution
how well the scanner tracks the changes in brain activity over time
why is temporal resolution good?
higher temporal resolution scanners are more responsive to short-term changes in the brain
Define voxel size
a 3D pixel, on the image of a scan
What is C.A.T stand for?
Computerised Axial Tomography
How are CAT scans similar to X-rays?
It involves passing x-rays though a person’s brain where the beams are then interpreted by a computer however, unlike an X-ray, it uses multiple angles of the brain
Why are CAT scans considered useful?
they are useful for detecting damage or tumours as well as allowing a detailed picture of the brain to be seen
What do CAT images show?
a grey-scale image, of high detail about the structure of the brain: images of bone, soft tissue and blood vessels imaged simultaneously
How are CAT scans inferior to PET/fMRI scans?
they do not convey information about brain activity or function which limits their psychological usefulness
how are CAT scan useful in terms of psychologically understanding?
Their level of detail in brain structures is useful when relating brain damage to psychological functioning
What are CAT scan’s resolutions?
Spatial resolution of 0.5mm (voxel size) and no temporal resolution as it only creates images of brain structure
How much does a CAT scan cost?
Around £1 million and takes round 5 minutes per scan, which roughly translates to £100-£400 per scan
What are the strengths of CAT scans?
Easier to plan surgeries as structures are seen before beginning the operation
Non-invasive, though sometimes a dye is injected for higher clarity
Removes the need for exploratory surgery
Reduces the time an individual must spend under general anaesthetic
Cheaper and somewhat faster than PET/fMRI scans
What are the weaknesses of CAT scans?
- Involves radiation, and therefore unadvised for pregnant women as radiation may harm the unborn child
- Risk of overexposure to radiation,
What does f.M.R.I stand for?
Functional Magnetic Resonance Imaging
How does an fMRI scan work?
It scans the blood flow in the brain. The individual’s head is placed within a large electromagnet, and they are given a task to do. As neural activity increases, so does blood flow: active areas require more blood and the scan shows where the blood goes. The haemoglobin within the blood dispels the magnetic field when oxygenated and goes with the magnetic field when deoxygenated - these differences help the scanner to create an image.
Why is fMRI scans favoured by scientists more so than PET scans?
It has a higher spatial resolution, non-invasive and lacks radiation exposure to the participant
Why is fMRI scan practically useful?
No need for radioactive tracers, although small movements may badly affect fMRI scans and so cannot be used to may different types of chemicals within the brain like PET scans`
How are fMRI scans similar to PET scans?
They both generate images of active brain areas, and so have the same applications and strengths
What is the resolution of fMRI scans?
1.5mm (voxel size) spatial resolution and a temporal resolution of 20 seconds
