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Flashcards in regeneration Deck (18)
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1
Q

Peripheral nervous system can reinnervate through

A

peripheral nerve sheaths

2
Q

In the CNS, there is a modest recovery

what are the Barriers:

A
  • Neuronal death
  • Glial cell inhibition of axon growth
  • Neural stem cells have limited capacity to -repair.
  • Immune responses in the nervous system, mediated by microglia, astrocytes, and oligodendrocytes, release cytokines that further inhibit extensive regrowth
3
Q

A stroke involving the middle cerebral artery can cause damage to

A

M1 and both SMA

4
Q

Mechanisms underlying functional improvement over time may include:

A
  • Unmasked surviving axonal connections
  • Signaling changes between surviving neurons
  • Modest growth of axon branches, dendrites
  • Altered activity in the contralesional (“healthy”) side may assist lesioned side
5
Q

Altered cortical activity patterns and functional recovery in stroke:
If there is good functional recovery, the altered cortical activity patterns

A

altered cortical activity patterns DIMINISH – paradoxical

6
Q

Altered cortical activity patterns and functional recovery in stroke:
If there is poor functional recovery

A

altered cortical activity patterns remain

7
Q

Three types of neuronal repair

A
  • Peripheral nerve regeneration – nerve cell bodies intact
  • Repair of existing neurons in the CNS -inhibited by glial cell overgrowth due to immune response
  • Neuronal replacement in the CNS – rare, and controversial
8
Q

who was Henry Head

A

he cut his own nerves (PNS regeneration experiment (1905))

9
Q

the stages of Regeneration of peripheral nerves:

A
  • Cross section through a peripheral nerve showing the connective tissue sheath of the epineurium and the extracellular matrix–rich perineurium that immediately surrounds the axons and Schwann cells.
  • Once the axon is cut, the distal portion degenerates and is phagocytosed by macrophages. After the debris is mostly cleared, the proximal axon stump transforms into a growth cone, and this growth cone interacts with the adjacent Schwann cells.
  • Distal to the proximal stump, extracellular matrix components, Schwann cells, immune cells, and connective tissue create a channel or space along which the axon regenerates towards the original target.
10
Q

Regeneration is more efficient after

A

crushing versus cutting a nerve.

11
Q

Molecular and cellular response in peripheral nerve regeneration:
Schwann cells facilitate peripheral axonal regeneration by?

A
  • They express adhesion molecules on their surface
  • Secrete axon growth-promoting signals (e.g. BDNF) and neurotrophins

*In parallel, the parent neuron expresses genes that restore it to a growth state.

12
Q

Three different classes of glia react in the CNS

A

Glia react strongly to brain insult

  • Astrocytes
  • Oligodendrocytes
  • Microglia
13
Q

Cellular response to injury in the CNS

A
  • Myelin degeneration
  • Production of inhibitory factors by astrocytes, oligodendroglia and microglia
  • Inhibitory factors inhibit axon regrowth
  • Glial scar forms
14
Q

Anterior subventricular zone – a stem cell niche

A

Stem cells become more glia
Close to blood vessels
Transit amplifying cells – neuroblasts

15
Q

Neurogenesis in humans

A
  • Very limited
  • Staying in hippocampus
  • Mostly targeting neuron number stability
  • Recovery after brain insult seems very limited
  • Even addition of neural stem cells in humans seems to have limited effects.
16
Q

Plasticity after stroke - MI

A
  • Motor cortex representation also changes, extending into healthy cortex
  • Motor unit synchronization improves gradually following stroke, paralleling improvements in fine motor control
17
Q

Recovery processes:

Spontaneous recovery?

A

due to reparative processes occurring immediately after the lesion (healing for 3-4 weeks)

18
Q

Recovery processes:

Reorganization of neural mechanisms: ?

A

influenced by use and experience (changes in synaptic efficacy – unmasking; sprouting; redundancy)