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Repair and Regeneration of the
Nervous System
What’s Capable of Being Repaired
or Regenerated?
• Whole Neurons
• Axons
• Synaptic clefts
• Neuromuscular junction
• Receptors
Whole Neurons
Death is programmed (apotosis) or immediated (necrosis)
If you had too much MSG…..
Axons (Peripheral Nerves)
Axons Derive From Growth Cones
How Do Axons Know Where To
Go?
• Blueprint Hypothesis
– Axons migrate towards a tissue in a predetermined manner
• Chemical Affinity Hypotheis
– Axons migrate towards a tissue based on
feedback from “chemoattractants” and
“chemorepellants”
– Ephrin (retractant), Semaphorins (both)
Signaling Disruption of Axon
Growth
Synaptic Clefts (Neuromuscular
Junction)
Principles of Neural Science (Kandel); Chapter 55
Formation of a Neuromuscular
Junction
• Growth cone approaches a new formed
myotube
• Forms an unspecialized contact
• Multiple axons converge on a single site
• All but one are eliminated
– Survival of the fittest
Principles of Neural Science (Kandel); Chapter 55
What Happens With a Loss of
Nerve and Tissue?
Principles of Neural Science (Kandel); Chapter 55
Differentiation of Synaptic vs. Nonsynaptic Regions
Principles of Neural Science (Kandel); Chapter 55
Receptor Aggregation
Neuregulin: enables the formation of AcH receptors at the neuromuscular junction
Cytoplasmic Proteins
• link receptors together
Macromolecular Complexes
• link pre- and post-synaptic membranes
together
Principles of Neural Science (Kandel); Chapter 55
Neurotrophic Factors
• Guide neuron survival and
outgrowth on neurons
• BDNF, NT-3, NT-4 and 5
• Hot factor to study beyond
neuron repair and
regeneration (drug
addiction)
Case Study: Stroke, Chemical
Warfare, and Neuregulin
Spinal Cord Regeneration with
Channel Rhodopsin
• Achieved through optogenetics
http://www.scientificamerican.com/video.cf
m?id=method-of-the-year-2010-12-22