Podcast
Questions and Answers
What is the role of Schwann cells in the PNS?
What is the role of Schwann cells in the PNS?
What occurs when an axon degenerates, and adjacent healthy axons grow out and synapse at the sites vacated by the degenerating axons?
What occurs when an axon degenerates, and adjacent healthy axons grow out and synapse at the sites vacated by the degenerating axons?
In the mammalian PNS, what is the rate of regrowth from the proximal stump of a damaged nerve?
In the mammalian PNS, what is the rate of regrowth from the proximal stump of a damaged nerve?
In lower vertebrates, what is the characteristic of neural regeneration?
In lower vertebrates, what is the characteristic of neural regeneration?
Signup and view all the answers
What is the result of cortical reorganization following damage to peripheral nerves?
What is the result of cortical reorganization following damage to peripheral nerves?
Signup and view all the answers
What is the mechanism of neural reorganization that involves the release from inhibition?
What is the mechanism of neural reorganization that involves the release from inhibition?
Signup and view all the answers
What is the result of cortical reorganization in blind individuals?
What is the result of cortical reorganization in blind individuals?
Signup and view all the answers
What is the characteristic of neural regeneration in the CNS of adult mammals?
What is the characteristic of neural regeneration in the CNS of adult mammals?
Signup and view all the answers
What is the result of transneuronal degeneration?
What is the result of transneuronal degeneration?
Signup and view all the answers
What is the mechanism of neural reorganization that involves the formation of new connections?
What is the mechanism of neural reorganization that involves the formation of new connections?
Signup and view all the answers
What is a key feature of rapid reorganization of cortical surface?
What is a key feature of rapid reorganization of cortical surface?
Signup and view all the answers
What is thought to play a role in the improvements observed after brain damage that do not result from true recovery of brain function?
What is thought to play a role in the improvements observed after brain damage that do not result from true recovery of brain function?
Signup and view all the answers
What is a potential approach to reduce brain damage by blocking neural degeneration?
What is a potential approach to reduce brain damage by blocking neural degeneration?
Signup and view all the answers
What is the main goal of constraint induced therapy?
What is the main goal of constraint induced therapy?
Signup and view all the answers
What is the highest incidence of Multiple Sclerosis found in?
What is the highest incidence of Multiple Sclerosis found in?
Signup and view all the answers
What is a common feature of phantom limbs?
What is a common feature of phantom limbs?
Signup and view all the answers
What is the main characteristic of Alzheimer's disease in its advanced stages?
What is the main characteristic of Alzheimer's disease in its advanced stages?
Signup and view all the answers
What is the primary symptom of Alzheimer's disease according to the amyloid hypothesis?
What is the primary symptom of Alzheimer's disease according to the amyloid hypothesis?
Signup and view all the answers
What is a potential benefit of cognitive and physical exercise?
What is a potential benefit of cognitive and physical exercise?
Signup and view all the answers
What is the kindling model of epilepsy?
What is the kindling model of epilepsy?
Signup and view all the answers
What is the primary mechanism of promoting recovery from CNS damage by promoting regeneration?
What is the primary mechanism of promoting recovery from CNS damage by promoting regeneration?
Signup and view all the answers
What is the purpose of the transgenic mouse model of Alzheimer's disease?
What is the purpose of the transgenic mouse model of Alzheimer's disease?
Signup and view all the answers
What is the main reason why educated people are less susceptible to the effects of aging related brain deterioration?
What is the main reason why educated people are less susceptible to the effects of aging related brain deterioration?
Signup and view all the answers
What is the result of depriving the distal segment of a cut axon from its cell body?
What is the result of depriving the distal segment of a cut axon from its cell body?
Signup and view all the answers
What is the primary goal of promoting recovery from CNS damage by neurotransplantation?
What is the primary goal of promoting recovery from CNS damage by neurotransplantation?
Signup and view all the answers
What is a key feature of enriched environments that can benefit recovery from CNS damage?
What is a key feature of enriched environments that can benefit recovery from CNS damage?
Signup and view all the answers
What is the difference between anterograde and retrograde degeneration?
What is the difference between anterograde and retrograde degeneration?
Signup and view all the answers
What is the result of early regenerative changes in the cell body of an axotomized neuron?
What is the result of early regenerative changes in the cell body of an axotomized neuron?
Signup and view all the answers
What is the purpose of the MPTP model of Parkinson's disease?
What is the purpose of the MPTP model of Parkinson's disease?
Signup and view all the answers
What is the effect of deprenyl on the MPTP model of Parkinson's disease?
What is the effect of deprenyl on the MPTP model of Parkinson's disease?
Signup and view all the answers
Study Notes
Neural Degeneration
- Transneuronal degeneration occurs when damaged neurons degenerate and spread to linked neurons by synapses.
- Anterograde transneuronal degeneration spreads from damaged neurons to the neurons on which they synapse.
- Retrograde transneuronal degeneration spreads from damaged neurons to the neurons that synapse on them.
Neural Regeneration
- Neural regeneration is the regrowth of damaged neurons.
- In mammals and higher vertebrates, neural regeneration is less successful compared to invertebrates and lower vertebrates.
- In adult mammals, regeneration is virtually nonexistent in the CNS and is limited in the PNS.
- In the mammalian PNS, regrowth from the proximal stump of a damaged nerve usually begins 2-3 days after axonal damage.
- The nature of the injury determines the outcome of regeneration:
- If original Schwann cell myelin sheaths remain intact, regenerating axons grow through them to their original targets.
- If the peripheral nerve is severed, regenerating axons may grow into incorrect sheaths and targets.
- If the cut ends are widely separated, there may be no meaningful regeneration.
CNS-PNS Differences
- Some CNS neurons can regenerate when transplanted to the PNS, but some PNS neurons cannot regenerate when transplanted to the CNS.
- Schwann cells in the PNS promote regeneration by clearing debris and producing neurotrophic factors and cell adhesion molecules.
- Oligodendroglia in the CNS do not clear debris or stimulate regeneration and can inhibit axon growth.
Collateral Sprouting
- When an axon degenerates, adjacent healthy axons grow out and synapse at the vacated sites, a process called collateral sprouting.
- This can occur from axon terminal branches or nodes of Ranvier on adjacent neurons.
Neural Reorganization
- Cortical reorganization occurs following damage in lab animals, with sensory and motor cortex being ideally suited for study.
- Damage can induce reorganization of the primary sensory and motor cortex, which has been studied in two conditions: peripheral nerve damage and cortical damage.
- Studies have shown that cortical areas can reorganize and adapt to new inputs, with the scale of reorganization being greater than previously assumed.
Cortical Reorganization in Humans
- Research has used brain imaging technology to study the cortices of blind individuals, showing an expansion of auditory and somatosensory cortex.
- The findings suggest continuous competition for cortical space by functional circuits.
- There is a functional consequence to this reorganization, with blind individuals demonstrating superior skills on auditory and somatosensory tasks.
Mechanisms of Neural Reorganization
- Two mechanisms of neural reorganization exist:
- A straightening of existing connections, possibly through release from inhibition.
- (Other mechanisms not specified)### Recovery of Function After Brain Damage
- Recovery of function after brain damage is poorly understood and difficult to study due to confounding variables.
- Cognitive reserve, equivalent to education and intelligence, plays a role in improvements observed after brain damage.
- Cognitive reserve allows individuals to accomplish tasks in alternative ways, rather than true recovery of lost brain function.
- Educated individuals are less susceptible to the effects of aging-related brain deterioration.
Neuroplasticity and Treatment
- Reducing brain damage by blocking neurodegeneration:
- Blocking neural degeneration in human patients has shown promise.
- Apoptosis inhibitor protein has been shown to reduce both neuronal loss and behavioral deficits.
- Promoting recovery from CNS damage by promoting regeneration:
- Transplanting sections of myelinated peripheral nerve or olfactory ensheathing cells can promote regeneration and recovery.
- These approaches have shown promise in animal models, but more research is needed.
- Promoting recovery from CNS damage by neurotransplantation:
- Transplanting fetal tissue or stem cells may help replace damaged neurons or myelin.
- Positive results have been seen in animal models, but more research is needed.
Neuroplasticity and Rehabilitative Training
- Rehabilitative training can promote recovery from CNS damage:
- In animal models, training and practice have been shown to reduce the expansion of cortical damage.
- Constraint-induced therapy, which involves tying down the unaffected arm, has been shown to improve motor function.
Benefits of Cognitive and Physical Exercise
- Cognitive and physical exercise can reduce the risk of neurological disorders:
- Exercise has been shown to increase dendritic branching, synaptic size, and levels of neurotrophic factors.
- Enriched environments have been shown to promote neuroplasticity.
Phantom Limbs: Neuroplastic Phenomena
- Phantom limbs are a common phenomenon in amputees:
- Most amputees experience sensations in the amputated limb, which can be so realistic that they may try to use the limb.
- Pain can be a significant issue, but may be treated by concentrating on moving the amputated hand.
Alzheimer's Disease
- Alzheimer's disease is a progressive, terminal disorder:
- It is characterized by neurofibrillary tangles and amyloid plaques.
- It is thought to be caused by the accumulation of amyloid plaques, which are toxic to neurons.
- Genetic factors play a significant role in the development of the disease.
Animal Models of Human Neuropsychological Diseases
- Kindling model of epilepsy:
- Repeated stimulation of the brain can produce a progressive development of convulsions.
- The kindling phenomenon is a permanent change, and can be produced by distributed stimulations.
- Transgenic mouse models of Alzheimer's disease:
- Mice engineered to express human genes associated with Alzheimer's disease develop amyloid plaques.
- A triple transgenic mouse model displays both amyloid plaques and neurofibrillary tangles.
- MPTP model of Parkinson's disease:
- MPTP, a toxin, can produce cell loss in the substantia nigra, similar to that seen in Parkinson's disease.
- Deprenyl, a monoamine agonist, has been shown to block the effects of MPTP in animal models.
Neuroplastic Responses to Nervous System Damage
- Neural degeneration:
- Anterograde degeneration occurs in the distal segment of a cut axon, and progresses quickly.
- Retrograde degeneration occurs in the proximal segment, and progresses gradually.
- Early degenerative changes to the cell body suggest that the neuron will ultimately die.
- Neural regeneration:
- Early regenerative changes indicate that the cell body is involved in a massive synthesis of proteins to replace the degenerated axon.
- But early regenerative changes do not guarantee the long-term survival of the neuron.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the process of neural degeneration, including transneuronal degeneration, and neural regeneration. Learn about the different types of degeneration and how neurons are affected.
