Brain Scanning Techniques Flashcards
What are CAT/CT scans?
A form of structural scan that show a picture of the brain inside the skull
What do CAT/CT scans allow specialists to do?
Allow specialists to identify any areas of damage or tumours
they allow a real, living brain to be seen without having to cut into the head of a patient
How do CAT/CT scans work?
CAT/CT scans use an x-ray and take slices of sections of the brain/body producing drawing of the slices
How can the slices for a CAT/CT scan be viewed?
The pictures of the slices can be viewed individually or put together to form a three-dimensional image of a part of the body or area of interest
How can CAT scans be used in psychology?
Can be used to understand damage to the brain
What is the procedure of a CAT scan?
The person lying on a moving platform to be passed through a scanner or for the person to lie still and the scanner move around them
Why is a dye (such as iodine) sometimes used in CAT scans?
Sometimes a dye (such as iodine) is used for highlighting purposes to make the images clearer
With respect to aggression, what are CAT scans able to provide?
Able to provide information relating to the size of brain regions of interest
e.g. looking for an abnormally small amygdala would link to heightened aggression
What else can CAT scans help identify?
Help to identify lesions in the brain resulting in a loss of neurons and connections
e.g. lesions in the prefrontal cortex are often seen in individuals who are violent
What are the strengths of a CAT scan?
Gives detail that wasn’t there before scanning
non-invasive and painless
What are the weaknesses of a CAT scan?
Can only provide a still image
radiation from x-ray should be kept to a minimum so repeated use of CAT scan not advised - limits effectiveness and also is an ethical issue
What are PET scans?
PET scans are functional scans that show images that can illustrate how the brain is working during different tasks
How do PET scans work?
A radioactive tracer is added to a chemical (usually glucose) that the body uses and is injected into a vein in the arm
The tracer travel around the body until it reaches the brain where the brain uses up the glucose as energy and the tracer begins to decay
As the tracer decays, it gives off positrons, so the more energy being used in different areas, the more positrons are being emitted.
The positrons collide with electrons and form gamma rays that are picked up by the scanner and show the amount of energy being used by different areas of the brain.
The recordings can be displayed as images for interpretation
What can PET scans be used for?
To study blood flow in the brain
e.g. if someone is talking during a PET scan the areas of most blood flow in the brain will be the areas used during talking and the scan can detect these areas thus the function of different parts of the brain can be found
What else can PET scans show?
Can show the size of the brain areas so they can be measured and compared between people
With respect to aggression, what do PET scans provide?
Provide information about the levels of brain functioning in different areas of the brain
What is an example of what information PET scans provide?
Raine used PET scan technology to establish levels of activity in areas such as the prefrontal cortex, amygdala and corpus callous of all of which have been linked to aggression
What are the strengths of PET scans?
Allow us to study neurotransmission more accurately
Reliable method
What are the weaknesses of PET scans?
Measure brain functioning and cannot measure the brain at rest
Can only locate generalised areas of brain activity and not specific locations
How does fMRI scanning work?
Patients are placed in a very large scanner that sends strong magnetic field through their head
The magnetic field causes the nuclei in hydrogen molecules in the brain to spin in a particular way, and this is picked up by the scanner.
Because hydrogen concentrations vary in different parts of the brain, it is possible for the scanner to produce a detailed image of the brain based on the amount of hydrogen molecules it identifies in different areas.
What do fMRI scans pick up on?
Pick up on changes of use in the brain areas depending on the task being carried out
What is the relations between blood flow and neuronal activity?
Blood flow and neuronal activity are linked so changes in blood flow relate to neuronal activity
What does fMRI look at?
fMRI look at the blood flow showing brain cell use of energy
What can be fMRI scan be viewed as?
May be viewed as a combination between CAT scan (looking at structure of the brain) and a PET scan (looking at the functioning of the brain) but no tracer injection is required with the fMRI
With respect to aggressions, what can fMRI scans be used to measure?
Can be used to measure aggressive behaviour and emotional responses in relation to a task undertaken whilst in the scanner
e.g. measuring emotional reactions to a series of faces displaying emotions by looking at the levels of activity in the amygdala
What are the strengths of fMRI scans?
Safer than other scans such as PET scan - no invasion, surgery or radiation
Produce higher resolution scans than PET scans and detection of changes in blood flow is very precise
What are the weaknesses of fMRI scans?
Cannot measure the brain at rest - no baseline measure
Cannot look at the actual receptors of neurotransmitters whereas PET scan can
