Blood supply and neuroplasticity

Question 1

Which artery supplies the anterior system? What about the posterior system?

Answer 1

Anterior - internal carotid

Posterior - vertebral arteries

Question 2

What does damage to the ACA cause?

Answer 2

Somatosensory motor deficit on contralateral body with the leg being more affected than the arm (due to somatotopic organization)

If prefrontal cortex affected then there can be changes in EF

Question 3

What does damage to the MCA cause?

Answer 3

Somatosensory motor deficit with the arm and face being more affected than the legs

Aphasias

If damage is on the right, then left neglect

Prefrontal cortex can also be affected leading to changes in EF

Question 4

What does the PCA supply?

Answer 4

Occipital lobe, thalamus, and inferior temporal lobe (including hippocampus)

Question 5

What deeper structures does the ACA have branches going to?

Answer 5

Anterior striatum
Hypothalamus
Anterior limb of internal capsule

Question 6

What deeper structures do branches from the MCA go to?

Answer 6

Caudate, putamen and GP

Posterior limb of internal capsule

Question 7

What deeper structures do branches from the PCA supply?

Answer 7

Posterior hypothalamus, thalamus, superior midbrain

Question 8

What is a hematoma?

Answer 8

A collection of clotting blood

Question 9

What is an epidural bleed caused by?

How dangerous is it?

Answer 9

Tear in the middle meningeal artery

Very dangerous - fast bleeding, can die overnight

Question 10

What is subdural hemorrhage caused by?

Answer 10

Tearing of the bridging veins (often due to impact), can be fast or slow, usually slow and not as dangerous as epidural bleeds

Question 11

What causes subarachnoid hemorrhage?

How dangerous is it?

Answer 11

Bleed from one of the arteries of the circle of willis

Very dangerous because free bleeding

Question 12

Is intracerebral hemorrhage deadly? What are the symptoms?

Answer 12

Can be deadly - symptoms are consistent with the area that is damaged

Question 13

What is the difference between regeneration and axonal sprouting?

Answer 13

Regeneration - damaged axons grow and find their way back to a target

Axon sprouting - axons from undamaged parts of neurons grow new branches

Question 14

What is reactive synaptogenesis?

Answer 14

When a synapse is formed in response to a stimulus (e.g. damaged axon)

Question 15

What is the process of axon breakdown in the PNS called? What occurs?

Answer 15

Wallerian Degeneration

Dead axon bits are swept away by macrophages

Question 16

What permits an axon to regrow to it’s target?

Answer 16

The neurolemma is intact (the part that surrounds the myelin) - Schwann cells provide growth factor for axon regrowth

Question 17

How does the CNS deal with degradation of an axon and why is it harder for it to recover?

Answer 17

Astrocytes do not create a neurolemmal tube

Gliotic scar formation prevents regrowth

Instead, the surrounding areas undergo axonal sprouting to recover the function

Question 18

What is use-dependent plasticity?

Answer 18

The cortex can reorganize itself and increase representation of parts that are used more often

Question 19

Describe plasticity after deafferentiation

Answer 19

When a peripheral connection is severed, the area of the cortex devoted to that will start to represent the nearby areas

Question 20

Describe the vicious cycle of learned non-use

Answer 20

If you don’t use something, the cortical representation gets smaller and it becomes harder to use it in the future

After brain injury, if you use it, you can develop cortical representation in nearby parts of the brain to continue doing the functional tasks you need to