studying the brain Flashcards
Why is it difficult to study the brain/ in isolation
-The brain is very complex and delicate
-Different regions of the brain work together to produce brain function so cannot be studied in isolation
what do CT scans show + process
-CT scans show visual structures of the brain and allows us to visualise any tissue damage
-For example, blood is less dense than brain tissue, CT scans can be used to locate damaged blood vessels, blood clots or area of blood in the brain after a patient has had a stroke
PROCESS
-a beam of x ray radiation is aimed at the patient from all around the body
-Digital x ray detectors are used to pick up the x ray radiation as it exits the patients body
-Denser tissues absorb more x ray radiation, so will show up as lighter on the scans
Uses of CT scans
-With CT scans, visible symptoms can be linked to areas of tissue damage
-Neurologists can use this information to work out what areas of the brain are responsible for which function
Negatives of CT scans
-CT scans are not recommended for pregnant patients or children due to the risks of increased exposure to x ray radiation
-However, there is very little risk of damage from this type of scan
How do MRIs work
-MRIs use a combination of magnetic field and radio waves to generate images through the body
Similarities and differences compared to CT scans
DIFFERENCES
-Soft tissue images are produced by MRIs at a higher resolution than CT scans
-MRIs are especially good at identifying and locating tumours, as tumours show up clearly in MRI scans
SIMILARITIES
-MRIs also determine and identify abnormal/ damaged brain tissues
-Similarly to CT scans, MRIs are also only able to analyse brain function by linking visible symptoms to areas of damaged tissues in the brain
PROs and CONs of using MRIs
CONS
-MRI scans are considerably more expensive to carry out than CT scans
-The magnetic firld produced by the MRI scanner can interfere with medical devidces such as pacemakers
-Individuals with such devices will not be able to use the MRI scanner
PROS
-MRIs carry less of a risk than CT scans as there is no x ray radiatio involved
-Tumours show up much more clearly on MRIs than CT scans, making it easier to identify and locate tumours
fMRI
fMRI has a similar function to MRIs in the way that is uses magnetic fields and radio waves to generate a cross section of the brain
Differences between MRI and fMRIs
-unlike MRIs, fMRIs allows brain function to be studied in real time
-fMRIs show the location of oxygenated blood in the brain, therefore indicating which regions of the brain are active at which time
-The scanner measures the ratio of oxygenated haemoglobin to deoxygenated
Example of the process of fMRIs + how do they work
-A patient can be asked to carry out a particular action, can be asked a certain question or can be asked to think about a certain topic
-Change in blood flow is then assessed
-The region that is associated with the certain action or thought will then light up in the scanner
Uses of fMRIs
-fMRIs can be used in medical diagnosis e.g determining the cause of seizures
-fMRIs can also be used in psychological research
How does a PET scanner work
-PET scanners use radioactive tracers that collect in area of the brain where there is increased blood flow, metabolism or neurotransmitter activity
-The tracer is introduced into the blood before the scan so the scanner can detect it
-PET scanners detect high levels of radioactivity, therefore it can measure the movements of the radioactive tracer across different brain regions
-Amounts of radioactive tracer in different areas of the brain can show if a brain region is inactive or active
Uses of PET scans
-PET scans can increase our understanding of specific disease e.g Alzheimer’s, where activity in certain brain regions decreases
-It can also be used to study the brain in real time
