Lecture 4 Flashcards
You can have two types of damage what are they?
Focal, allows for good anatomy function interpretations
Diffuse, difficult to make anatomy function interpretations because the damage isn’t localised .
Also harder to detect because it might be microscopic or in the White matter
When you study brain lesions of a patient what is one key thing you must always remember to think about?
Timing, if the lesion happened a while ago other areas might have atrophied because of damaged blood vessels so you should always rescan
The other side of the coin is that there can be spontaneous recovery and plasticity in the brain
What is the definition of TBI?
Give some examples
Brain damage due to external physical forces Concussion Laceration Haemorrhaging Direct damage
What’s the definition of a stroke?
What are the two types?
Rapid damage to the brain because of loss or reduction of blood supply to certain areas
Ischemic stroke - loss of blood supply because of a clot leads to infarction
Hemorrhagic stroke - accumulation of blood in the skull vault leads to pressure on different brain areas
What’s an example of a disease that can lead to brain damage?
Meningitis
Herpes encephalitis
Alzheimer’s
What is the definition of a tumour?
What makes certain ones benign ?
Abnormal cell growth which are malignant or benign
Benign ones doesn’t spread beyond the infected cells
What exactly do they do? Why do tumours cause such problems?
They displace local populations of neurons and affects their metabolism without destroying the neurons immediately
Creates pressure or steals the oxygen supply of nearby cells
Why are they often so hard to detect? How do you detect them?
They don’t necessarily kill the cells of immediately. So PET is the only way to detect them through the change they cause in the metabolism of the infected cells.
What are T2 weighted MRIs useful for?
Useful for picking up damage or cell death because they appear bright white
PET scans are pretty good for this as well
Why is it useful to run multiple visualising techniques?
Some scans won’t pick up the damage for example a CT testing glucose metabolism won’t pick up damage that a PET scan testing opiate binding will.
What are the two normal ways of grouping patients when testing them?
Lesion defined - patients with lesions in a similar place eg Broca’s areas are all grouped and behaviour assessed compared to a control
Behaviour defined - patients with similar impairments are grouped and their lesions are reconstructed in a standard brain space and compared to a control
What does VLSM stand for ?
Voxel based lesion symptom mapping
How many voxels are there in the brain?
10,000
If you have a language comprehension task and a language production task, what’s the basic idea of VLSM?
You look at whether one group of patients have a lesion in that particular voxel, you then compare the groups score to another control group or group with differing lesion add area and impairment. If the score is different on the language comprehension and their lesion is on that voxel, then you can assume that that voxel is important for language comprehension but not for production.
Repeat for every voxel and mark using different colour
If the performance is the Same for the two groups and one group has a lesion on that voxel what does it mean?
Means that that voxel isn’t involved in speech or language
