Nervensystem II: ausgewählte Kapitel
Infos und facts for the second Neuro exam
Infos und facts for the second Neuro exam
Kartei Details
Karten | 88 |
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Sprache | English |
Kategorie | Medizin |
Stufe | Universität |
Erstellt / Aktualisiert | 17.06.2018 / 25.10.2018 |
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What are the 6 processes by which a neuron develops in the brain?
- cellular proliferation
- neuroblast and glioblast formation
- axonal projection and pathfinding
- dendritic proliferation and synaptogenesis
- Fissures and sulci
- Myelination
Neuroembryology: cellular proliferation:
- where are the progenitor cells?
- regulation?
- cellular proliferation in the adult brain?
- where can you find which glial cells (3 places, 4 types of neurons)
- multipotent, undifferentiated neuroepithelium surrounds the ventricular system
- regulation by genes -> conserve a constant ratio of synaptically related cells
- in the adult brain -> Dendate gyrus of the hippocampus and in the olfactory bulb
- 3 Zones:
- vetricular zone: apical radial glial cells; apical intermediate progenitors
- subventricular zone: basal intermediate progenitor
- intermediate zone: migrating neurons
neuroblast and glioblast migration:
- migration of inhibitory GABAergic interneurons
- Migration of Glioblasts
- Genetic regulation
- GABAergic interneurons:
- originiate in the ganglionic eminence of the SVZ
- migrate tangentially along axons
- comprise 20% of total cortical neurons
- Glioblast: are the majority of radial migratory cells to the cortex in the second half of gestation
- Ogrganization mostly by the gene Reelen: expressed by Cajal-Retzius cells of the molecular zone
Disorders of neuroblast migration
Definition
3 examples
causes
= are classified by their effects on sulcation and gyration of the cortex. They develop earlier than the formation of the gyri.
Examples: lissencephaly, Polymicrogyria, pachygyria
Causes: congenital infections: CMV, congenital rubella etc.
Axonal projection and pathfinding:
- Dendrites or Axons first?
- growing axons
- disorders
- axons always form earlier than dendrites
- growth cone = growing axon -> is guided by chemical signals that attract or repell (secreted by ependynal cell basal process)
- the axonal terminal proliferates to innervate many neurons
- Disorders:
- defective guidance -> axons that project to aberrant sites
- agenesis of the corpus callosum
- defective guidance -> axons that project to aberrant sites
Dendritic proliferation and Synaptogenesis
- when do the dendrites proliferate?
- Disorders of dendrites and synapses?
1. the dendritic tree of each neuron proliferates only after the neuron is in its final site within the CNS
2. Disorders of dendrites and synapses?
- Down syndrome --> same as FAS
- Fetal alcohol syndrome --> abnormal dendritic spines and lack of dendritic branches in the cerebral cortical neurons
- Autism spectrum disorder
- Epilepsy
Autism spectrum disorder
- what it be
- what is the converging problem?
You have impaired social and communicative skills& repetitive behaviours
Converging problem: connectivity:
- Decrease in connectivity between specific brain regions --> Hypoconnectivity (defective axon growth and guidance)
- Increase in connectivit within regions --> Hyperconnectivity (to many neurons, dendrites, spines -> lack of apoptosis)
Epilepsy
- what is the effect on axon wiring?
- what happens after recurrent seizures in the hippocampus?
1. Seizures induce changes in axon guidance proteins -> rewiring of neuronal circuits in later stages of epillepsy
2. recurrent seizures in the hippocampus -> new mossy fibre collaterals which abberrantly innervate the molecular layer and synapse with their own dendrites -> self-stimulation