NEURO: Introduction to Clinical Neuroscience Flashcards
What is the function of the CSF?
The CSF acts as a conduit for cleaning out toxins, and it acts as a cushion for the brain.
What are the different parts of a neuron, and what do they do?
A neuron is made up of 3 main parts: the dendrites, the cell body and the axon.
The dendrites receive signals from other neurons; these get processed in the cell body, and the signal is transmitted down the axon to other cells.
How is AI based on our brains?
This structure of having cell bodies that process signals from many cells and sending them out to other cells is what has been turned into what we call the artificial neural network.
Artificial intelligence and deep learning are based on structures like this, where there is a computer version of the brain. You can have a signal into the node, and that node may or may not send out signals to other nodes. All the nodes are interconnected.
What do the cases of brain damage prove to us?
They show us how, when a certain area of the brain is affected/damaged, certain traits/functions are consequently affected.
This proves that different brain areas were responsible for governing different functions.
List some different brain diseases and how they affect the brain.
- Glioblastoma: It’s a highly infiltrative, malignant brain tumour. It’s not easy to remove the tumour because of how infiltrative it is; we would have to remove a large part of the brain as well.
- Haemmorrhagic stroke: It occurs when blood vessels to the brain are blocked, killing off the part of the brain supplied by those vessels. Its damage is quite localised.
- Hippocampal sclerosis: This is a structural change in the hippocampus. It can cause seizures, and it found in Alzheimer’s and other dementias.
Briefly, describe how X-ray CT imaging works.
X-rays are beamed through the patient; those are detected on the other side. Thus, the brain is measured at different angles.
With complex mathematics, those separate lines can be turned into a 2D image.
Briefly, describe how MR imaging works.
A radio frequency pulse is sent into the brain that interacts with all the positive protons of hydrogen molecules. These protons generate a signal from within the tissue that is picked up by frequency coils.
After some computer processing, it’s turned into the 2D image that we see.
What is T2 in MRIs, and how does it change based on brain damage?
T2 weighted image (T2WI) is one of the basic pulse sequences in MRI. The sequence weighting highlights differences in the T2 relaxation time of tissues.
Increased tissue water and loss of cellular structure all lead to increased T2.
What can we see as a result of increased specificity of MRIs?
We can see degenerative changes, developmental abnormalities and disease-specific changes.
How does MRI show white/grey matter contrast?
T1w images give grey and white matter contrast.
In grey matter, water (in both intra- and extracellular compartments) has relatively free motion.
In white matter, approximately 50% of the tissue volume is accounted for by myelin structures, within which T1 relaxation of hydrogen in lipid structures is very short.
Hence, the average T1 of WM < GM.
What is diffusion MRI used for?
Diffusion MRI used to highlight white matter pathways and how they’re connected.
It uses the diffusion of water molecules to generate contrast in MR images.
How do we get a 3D MR angiogram of the brain?
Very short TRs of about 10 nm are used. The inflowing blood provides a high signal against a darker background tissue signal.
What is the basis of the fMRI?
Increased glucose and O2 extraction lead to increased blood flow, which leads to reduced heamoglobin and so an MRI signal increase.
What is the basis of PET scanning?
Radionuclides are incorporated into pharmaceuticals that are specific for metabolic processes or cell receptors. The injected radiopharmaceutical generates a localised gamma ray signal relating to metabolism of cellular function.
