10.9

• the development, or genesis, of epilepsy

  epileptogenesis
• True or False: It must be stressed that the kindling model as it is applied in most laboratories does not model epilepsy in one important respect.

  True
• It was quickly established that nonhuman primates respond to MPTP in many of the same ways that humans do. They display Parkinsonian motor symptoms, cell loss in the substantia nigra, and a major reduction in brain dopamine. This happened in what widely used animal model.

  MPTP Model of Parkinson’s Disease
• Neural degeneration (neural deterioration and death) is a component of both brain development and disease.
• Neural degeneration is greatly influenced by nearby glial cells, by the activity of the degenerating neurons, and by the particular cause of the degeneration.
• Neural degeneration is often induced in a simple, controlled way: by cutting axons (i.e., by axotomy).
• Two kinds of neural degeneration ensue: anterograde degeneration and retrograde degeneration.
• Anterograde degeneration is the degeneration of the distal segment —the segment of a cut axon from the cut to the synaptic terminals.
• Anterograde degeneration is the degeneration of the distal segment —the segment of a cut axon from the cut to the synaptic terminals
• Retrograde degeneration is the degeneration of the proximal segment —the segment of a cut axon from the cut back to the cell body.
• Retrograde degeneration is the degeneration of the proximal segment—the segment of a cut axon from the cut back to the cell body.
• Anterograde degeneration occurs quickly following axotomy because the cut separates the distal segment of the axon from the cell body, which is the metabolic center of the neuron. The entire distal segment becomes badly swollen within a few hours, and it breaks apart into fragments within a few days.
• The course of retrograde degeneration is different; it progresses gradually back from the cut to the cell body. In about 2 or 3 days, major changes become apparent in the cell bodies of most axotomized neurons. These early cell body changes are either degenerative or regenerative in nature.
• Early degenerative changes to the cell body suggest that the neuron will ultimately die—usually by apoptosis but sometimes by necrosis or a combination of both.
• Early regenerative changes indicate that the cell body is involved in a massive synthesis of the proteins that will be used to replace the degenerated axon
• Degeneration spreads from damaged neurons to neurons that are linked to them by synapses; this is called transneuronal degeneration.
• Transneuronal degeneration spreads from damaged neurons to the neurons on which they synapse; this is called anterograde transneuronal degeneration.
• It spreads from damaged neurons to the neurons that synapse on them; this is called retrograde transneuronal degeneration.
• Neural regeneration —the regrowth of damaged neurons— does not proceed as successfully in mammals and other higher vertebrates as it does in most invertebrates and lower vertebrates.
• True or False: Regeneration of axons is virtually nonexistent in the CNS of adult mammals.

  True