Introduction to clinical neuroscience Flashcards
What is the dura and what does it contain?
Dura is the bag that surrounds the whole brain and contains CSF and the brain itself
What does CSF act as and what can it provide?
CSF acts as a conduit for clearing out toxins and can also provide nutrients for the brain as well as a cushion for the brain
What supplies the brain for energy?
Arterial system supplies the brain for energy
What are grey matter?
astrocytes, glia and neurons are grey matter
What is white matter?
White matter is all the bits of connectivity between the grey matter
What does a typical brain cell have?
Typical brain cell has:
- A cell body
- Dendrites
- long axon
How are signals transmitted through brain cells?
Dendrites receive signals from other neurons and these signals get processed in the cell body and then a signal is transmitted down the axon to other cells via dendrites
What is a glioblastoma?
A highly infiltrate brain tumour
When does a hemorrhagic stroke occur and what does it cause?
- Its when blood vessels are blocked
- Causes localised damage
What happens in hippocampal sclerosis and what can it cause?
- Structural change occurs
- Causes seizures
Where do the effects of alzheimer’s start?
Starts at the hippocampus
What do x-rays pass through and not pass through and what does this allow?
Passes through air but not bone therefore allows imaging of bone
What does it mean when signals are bright or dark in a x-ray CT?
- If signals are bright, it shows strong attenuation of the x-rays
- If the signals are dark, it means x-rays can go through fairly easily
How is an image produced for a MRI?
- Water have hydrogen atoms which have a proton
- Radiofrequency pulse put in which interacts with protons and these protons generate a signal which are picked up by radiofrequency coils giving us the image
What does signal intensity increase with in T2w MRI?
Signal intensity increases with increased water content
What leads to an increased T2?
Increased tissue water and loss of cellular structure all lead to an increased T2
What resolution does T1w MRI imaging have?
Has 1mm spatial resolution
What can you view in T1w MRI imaging?
- Degenerative change
- Developmental abnormalities
- Disease specific changes
Why is the T1 is WM
- In grey matter there’s water in both intra and extracellular compartment and has relatively free motion
- In white matter approximately 50% of the tissue volume is accounted for by myelin structures. The protons of the CH3 in myelin and H20 in the axon create signalling for white matter
- Hence T1 of WM
What are white matter tracts?
-Long myelinated axons that connect different parts of the brain
What do white matter tracts have making them efficient?
White matter tracts have myelin sheaths that allows efficient conduction of signals
What happens in multiple sclerosis to the myelin sheath?
In multiple sclerosis, the myelin sheath degrades effecting signals in different parts of the brain
What present in the centre of the white matter tracts and what do they contain?
Microtubules and microfilaments which contain water
What’s the direction of the white matter pathway?
Where there is the maximum diffusion of water, that’s the direction of the white matter pathway
What TR is used in 3D angiography of the brain?
Very short TR of about 10ms used
What type of signal does inflowing blood provide in a 3D angiography of the brain?
Inflowing blood provides a high signal against a darker background tissue signal
What does increased extraction of glucose and O2 in bold fMRI lead to?
Increased glucose and O2 extraction leads to increased blood flow which leads to reduced Hb and so a MRI signal increases
What does PET enable?
Enables to image particular chemicals
Steps involved in a PET scan
- A radioactive nucleus decays releasing a positron and combine with electron releasing 2 gamma rays at 90 degrees
- These gamma rays are detected and then provide an image
