Introduction to Clinical Neuroscience (neuro)

Question 1

Clinical, Neuro and Science

Answer 1

Clinical:

• human disease:
• diagnosis
• treatment
• mechanisms

Neuro:

• brain
• spine
• peripheral
• nervous system
• gut
• stroke
• tumours
• MS
• schizophrenia
• depression
• input from PNS may alter brain function (chronic pain)
• toxins can affect. brain function:
  1) urea (kidney disease)
  2) ammonia (liver disease)
  3) sugar, alcohol, nicotine, etc
• behavioural/ environmental factors can be detrimental (stress, isolation, internet use)
• behavioural/ environmental factors can boost brain function (exercise, education, enjoyment, engagement)

Science:

• mechanistic studies
• biomarkers
• cells to whole body

Question 2

Neuroimaging

Answer 2

• the brain is a highly connected network with both local and distributed functionality

Neuroimaging provides information on:

• gross structural and pathological change (CT/MRI)
• anatomical and development change (MRI)
• metabolite levels (MRS)
• blood flow (CT, PET, MRI)
• metabolism (PET)
• connectivity (diffusion MRI)
• functionality (fMRI, PET)
• receptors (PET)

Question 3

Why is the Stroop test is so hard? What does it tell about how we process information?

Answer 3

• We are primed/trained to read, hence recognition and interpretation of words has priority and is a
  subconscious process that is hard to override.
• For example, I xpct y hvae liltte diicultffy n rdaeing tihs dpseite
  teh mdduled ltteers.
• Hence the word-reading program is well ahead in its processing pathway compared to the
  conscious process you are being asked to perform to recognise the colours.
• Our world is interpreted with a
  balance between subconscious bias and forced attentionality.

Question 4

Give and advantage and a disadvantage of performing histopathological studies on post mortem brain

Answer 4

• Advantage: detailed microscopic histopathological analysis to understand disease effects and processes (e.g.
  can stain for structures such as blood vessels, particular cell-types such as neurones, chemical types such as
  amyloid…. ) and this info could be related to clinical aspects of the disease when the patient was alive
• Disadvantage:
  Post-mortem studies don’t provide prognosis/diagnosis for an actual patient – but see above- could help
  others. There could be changes in the brain that don’t relate to any clinical symptoms, so need to be careful
  how we interpret post-mortem observations.

Question 5

What pathological/structural changes in brain tissue cause lesions to appear bright on T2-weighted images?

Answer 5

• Bright regions on T2w images suggest increased free water content or loss of tissue structure, so
  oedema, cellular damage, reduced cell density, necrosis, inflammation, demyelination, can all be
  causes of bright T2w lesions

Question 6

Describe two physical/structural properties of neurones that enable uniquely different types of MR image to be acquired

Answer 6

1) The myelination of the axon of neurones leads to a lower water T1 relaxation time in white matter
compared to the T1 of grey matter, hence in T1-weighted images GM and WM can be distinguished for
assessing anatomical changes
2) The tubular structure of axons leads to the diffusivity of water within them to be very directional.
Measuring the direction of maximum water diffusion allows us to determine the orientation and
connectivity of white matter pathways

Question 7

Give 3 properties/ aspects of blood that are used to provide unique types of diagnostic imaging

Answer 7

1) Blood flow gives different MRI properties of the water in blood to the water in static tissue. A T1w
image shows tissue as dark, but the flowing blood shows up as bright.
2) The deoxyhemoglobin in blood is paramagnetic and its presence reduces the MRI signal in a T2w
image. Changes in blood deoxygenation are used to detect changes in blood flow that occurs in
functional activation of the brain in fMRI
3) Blood can act as a transporter of radiopharmaceuticals into the brain that undergo metabolic
processes or bind to specific receptors for PET imaging

Question 8

Give one advantage and one disadvantage of 1H MRS as a diagnostic tool

Answer 8

Advantage:
MRS provides signals from a variety of chemicals (NAA, choline, creatine…) in the brain that may
change with disease (cancer, schizophrenia, stroke…..)

Disadvantage:
Single voxel MRS needs a volume of about 15mm cube to generate a strong enough signal – so doesn’t
provide whole brain coverage and there is a need to know which single part of the brain the spectrum
needs to be acquired from