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Questions and Answers
What is the process called where precursor cells develop into neurons and glial cells?
What is the process called where precursor cells develop into neurons and glial cells?
During which developmental stage does the neural plate start to form the neural tube?
During which developmental stage does the neural plate start to form the neural tube?
What initiates the migration of neural crest cells during nervous system development?
What initiates the migration of neural crest cells during nervous system development?
Which process involves the elimination of excess neurons during development?
Which process involves the elimination of excess neurons during development?
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What is primarily responsible for the formation and maturation of synapses during development?
What is primarily responsible for the formation and maturation of synapses during development?
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Which of the following factors can influence neuron survival during development?
Which of the following factors can influence neuron survival during development?
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What characteristic does the neural tube division create for future brain development?
What characteristic does the neural tube division create for future brain development?
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At what stage does the notochord play a crucial role in nervous system development?
At what stage does the notochord play a crucial role in nervous system development?
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Which developmental process involves the reorganization of synaptic connections?
Which developmental process involves the reorganization of synaptic connections?
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What stage follows the gastrula in embryonic development?
What stage follows the gastrula in embryonic development?
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What is one consequence of visual enrichment on the brain's structure?
What is one consequence of visual enrichment on the brain's structure?
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During which time frame does monocular deprivation significantly affect the organization of ocular dominance in the primary visual cortex?
During which time frame does monocular deprivation significantly affect the organization of ocular dominance in the primary visual cortex?
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Which process involves the addition of a methyl group to suppress gene expression?
Which process involves the addition of a methyl group to suppress gene expression?
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What experience-related factor significantly influences the expression of the GR promoter in the hippocampus of offspring of certain rat mothers?
What experience-related factor significantly influences the expression of the GR promoter in the hippocampus of offspring of certain rat mothers?
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In the context of aging, which cognitive function typically shows decline?
In the context of aging, which cognitive function typically shows decline?
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What is the common characteristic of neurofibrillary tangles found in Alzheimer's Disease?
What is the common characteristic of neurofibrillary tangles found in Alzheimer's Disease?
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What is not a protective factor against age-associated memory impairment (AAMI)?
What is not a protective factor against age-associated memory impairment (AAMI)?
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What happens to dendritic spines as a result of estrogen loss in aging females?
What happens to dendritic spines as a result of estrogen loss in aging females?
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What is the role of glucocorticoids in relation to the hippocampus?
What is the role of glucocorticoids in relation to the hippocampus?
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Which statement about the genetic basis of Alzheimer's Disease (AD) is accurate?
Which statement about the genetic basis of Alzheimer's Disease (AD) is accurate?
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What is one effect of competitive synapse activity during development?
What is one effect of competitive synapse activity during development?
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What is a notable feature of vascular or multi-infarct dementia?
What is a notable feature of vascular or multi-infarct dementia?
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What is a consequence of oxidative damage and inflammatory responses during aging?
What is a consequence of oxidative damage and inflammatory responses during aging?
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Which of the following factors is correlated with cognitive decline as individuals age?
Which of the following factors is correlated with cognitive decline as individuals age?
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Which process involves the movement of precursor cells to their final locations in the developing nervous system?
Which process involves the movement of precursor cells to their final locations in the developing nervous system?
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What is the main role of the radial glia during migration in the central nervous system?
What is the main role of the radial glia during migration in the central nervous system?
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In synaptogenesis, what process describes the interaction between growth cones and guiding molecules?
In synaptogenesis, what process describes the interaction between growth cones and guiding molecules?
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What initiates the process of apoptosis in developing neurons?
What initiates the process of apoptosis in developing neurons?
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Which of the following statements accurately describes the role of Bcl-2 proteins in apoptosis?
Which of the following statements accurately describes the role of Bcl-2 proteins in apoptosis?
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What occurs during synaptic rearrangement in developing neural circuits?
What occurs during synaptic rearrangement in developing neural circuits?
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What is the primary role of chemoaffinity in synaptogenesis?
What is the primary role of chemoaffinity in synaptogenesis?
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What happens to cells that fail to make appropriate connections in the nervous system?
What happens to cells that fail to make appropriate connections in the nervous system?
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Which of the following best describes the competitive nature of neuronal survival?
Which of the following best describes the competitive nature of neuronal survival?
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What occurs during the process of myelination in neural development?
What occurs during the process of myelination in neural development?
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Which stage of neural development includes the differentiation of precursor cells into specialized cell types?
Which stage of neural development includes the differentiation of precursor cells into specialized cell types?
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What is a potential effect of environmental impoverishment on the visual cortex?
What is a potential effect of environmental impoverishment on the visual cortex?
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What is the significance of topographic gradients during synaptic rearrangement?
What is the significance of topographic gradients during synaptic rearrangement?
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Which cellular structure is primarily altered during apoptosis?
Which cellular structure is primarily altered during apoptosis?
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Study Notes
Development of the Nervous System
- Nervous system development involves seven key processes: neurogenesis, migration, differentiation, synaptogenesis, apoptosis, synaptic rearrangement, and myelination.
- Experience and epigenetics play a role in development, affecting aging as well.
- Ongoing neurogenesis, vascular dementia, stress and Alzheimer's disease are factors linked with aging of the nervous system.
Stages of Development
- Zygote: A fertilized egg, a single cell.
- Blastocyst: A hollow sphere of stem cells with pluripotential capabilities.
- Gastrula: A three-layered form resulting from a partially differentiated blastocyst.
- Embryo: Composed of three layers—ectoderm, mesoderm, and endoderm.
- Fetus: Recognizable in relation to its mature form.
Neurulation
- Neurulation involves the dorsal epithelial layer (ectoderm) thickening to form a neural plate.
- The neural plate folds to create a neural groove and neural tube, which ultimately forms the central nervous system.
- This occurs around 18-22 days.
Cells of the Nervous System
- Neural crest cells break off during neurulation and migrate, forming the peripheral nervous system, guided by chemical signals.
- Sensory organs originate, at least partly, from sensory placodes. These include olfactory, lens, trigeminal, geniculate, epibranchial, petrosal, and otic placodes.
Cell Migration
- Cells of the neural crest migrate to their final destinations guided by chemical signals, contributing to the peripheral nervous system's structure.
- Important to note that migration occurs in waves, with different waves creating different regions of the brain.
Differentiation
- Dividing pluripotent cells differentiate into non-dividing neuroblasts and glioblasts.
- The cells mature into specialized neurons or glial cells.
- Remaining ventricular cells differentiate into ependymal cells lining the ventricles and spinal cord.
- Different cell types undergo different processes depending on their location and function.
Synaptogenesis
- Synaptogenesis involves the growth of axons, dendrites, and synapses.
- Filopodial structures from growth cones extend and contract.
- Target cells release chemical labels that attract growing axons.
- Pioneer growth cones interact with NCAMs to guide subsequent neurons' growth, creating stereotyped axonal paths and making a complex structure in a consistent way.
Apoptosis
- Exuberant cell proliferation in early development is followed by programmed cell death (apoptosis).
- Cells not contacting their appropriate target undergo apoptosis.
- Glial cells can undergo apoptosis, and progenitor cell careers end due to apoptosis.
Synaptic Rearrangement
- Neurons that fire together wire together (Hebbian principle).
- Synaptic contacts become more focused over time.
- Synaptic density peaks around one year of age and then decreases.
- Throughout prenatal and postnatal life, and across the different stages of development, patterns of synaptic contact shift.
Myelination
- Myelination, the formation of myelin sheaths, starts around 24 weeks after conception.
- It begins in the spinal cord and progresses to other brain regions.
- A high-intensity phase of myelination occurs in the early postnatal period.
- Myelin sheath formation occurs in stages and may vary across regions.
Environmental Influences
- Environmental enrichment promotes thicker cortex, more dendrites, and more synapses.
- Visual deprivation results in fewer synapses and spines in primary visual cortex, leading to deficits in visual perception.
- Experience significantly shapes the functional organization of the brain, particularly in the visual cortex.
Aging
- Aging continues neurogenesis and migration in specific areas (hippocampus, caudate nucleus, olfactory bulb).
- Age-associated memory impairment (AAMI) varies from mild cognitive impairment to profound dementia.
- Cognitive function remains intact until advanced age in most individuals.
- Age-related changes can affect the ability to acquire and store new information.
- Factors such as education and profession may influence AAMI risk factors, while mood and depression are significant correlates to cognitive decline.
Alzheimer's Disease
- Alzheimer's disease is the most common form of age-related dementia.
- It involves the accumulation of amyloid plaques and neurofibrillary tangles.
- The disease often starts in the hippocampus and overlying cortical areas and progressively spreads.
- Genetic factors, like mutations in amyloid precursor protein genes or certain alleles of the apolipoprotein E gene, influence both early-onset and late-onset types.
- Early-stage symptoms often involve difficulties with memory, language, and identification of objects or words.
- In later stages, patients may become mute and severely disabled.
Epigenetics
- Epigenetics describe how experiences affect gene expression throughout a lifespan.
- DNA methylation, adding methyl groups to DNA, can turn off genes in a stable way.
- Histone acetylation affects how tightly DNA is wrapped around proteins and is involved in gene activity, which is affected by environmental factors.
- There are also wider influences, including development, environmental chemicals, pharmaceuticals, diet, and aging.
Vascular Dementia
- Vascular dementia can be caused by larger infarcts (>50ml) or smaller lacunar infarcts (1ml).
- Risk factors include hyperlipidemia, diabetes mellitus, hyperhomocysteinemia, smoking, elevated C-reactive protein, cerebral amyloid angiopathies.
Hippocampus Atrophy
- Chronic stress and elevated glucocorticoids can lead to hippocampal atrophy.
- This is likely due to shrinkage in dendritic arborization.
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Description
This quiz focuses on the key processes involved in the development of the nervous system, including neurogenesis, synaptogenesis, and myelination. It also covers the stages of development from zygote to fetus and the process of neurulation. Test your understanding of these essential concepts in neurodevelopment.
