Development of the Nervous System Chapter 9
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Questions and Answers

What is the first major stage of neurodevelopment in all vertebrates?

  • Neural Proliferation
  • Induction of the Neural Plate (correct)
  • Neural Aggregation
  • Axon Growth and Synapses Formation

    • Stem cells are cells that only have the ability to develop into one specific type of mature cell.

    False

    What is the region adjacent to the ventricles where most cell division in the neural tube occurs?

    ventricular zone

    During migration, cells lacking the processes that characterize mature neurons engage in ___________.

    <p>Somal translocation</p> Signup and view all the answers

    Match the following neurodevelopment stages with their descriptions:

    <p>Neural Proliferation = Process where cells proliferate in a particular sequence responsible for brain shape Migration and Aggregation = Involves immature cells moving and aligning to form neural structures Axon Growth and Synapses Formation = Includes the extension and retraction of filopodia in growing neurons</p> Signup and view all the answers

    What is the term used to describe the tendency of developing axons to grow along paths established by preceding axons?

    <p>Fasciculation</p> Signup and view all the answers

    Neuron death is a passive process called necrosis.

    <p>False</p> Signup and view all the answers

    What is the role of glial cells, particularly astrocytes, in synaptogenesis?

    <p>Glial cells, particularly astrocytes, play a role in promoting synaptogenesis by enhancing the formation of synapses.</p> Signup and view all the answers

    The most exciting recent discovery about synaptogenesis depends on the presence of __________ cells, particularly astrocytes.

    <p>glial</p> Signup and view all the answers

    Match the following brain development phases with their descriptions:

    <p>Synaptogenesis = Formation of synapses Myelination = Increases speed of axonal conduction Dendritic branching = Progresses from deeper to more superficial layers Neuron death = Occurs in waves throughout development</p> Signup and view all the answers

    What are the common consequences of neurological dysfunction mentioned in the text?

    <p>All of the above</p> Signup and view all the answers

    What is the major cause of cerebral hemorrhage?

    <p>Cerebral blood vessel ruptures</p> Signup and view all the answers

    What is the area of dead or dying tissue produced by a stroke called?

    <p>infarct</p> Signup and view all the answers

    Is an aneurysm a pathological balloon-like dilation that forms in the wall of an artery?

    <p>True</p> Signup and view all the answers

    Cerebral ischemia is a disruption of the blood supply to an area of the _______.

    <p>brain</p> Signup and view all the answers

    What are permissive experiences in terms of neural development?

    <p>Experiences that are necessary for genetic programs to be manifested</p> Signup and view all the answers

    Sensitive periods for experiences in neural development can occur outside a specific interval.

    <p>True</p> Signup and view all the answers

    What is the competitive nature of experience related to in terms of ocular dominance columns?

    <p>ocular dominance</p> Signup and view all the answers

    Autism is a complex neurodevelopmental disorder characterized by a reduced ability to interpret __________ and intentions of others.

    <p>emotions</p> Signup and view all the answers

    Match the following characteristics of William Syndrome with their corresponding descriptions:

    <p>Sociable, empathetic, and talkative = Typical traits seen in patients with William Syndrome Thinning of the cortex and underlying white matter = Common feature observed in individuals with William Syndrome Opposite spatial abilities = Deficit often noted in individuals with Williams Syndrome Short with small upturned noses, oval ears, broad mouths = Physical features associated with Williams Syndrome</p> Signup and view all the answers

    What are the primary symptoms of a grand mal seizure?

    <p>Loss of consciousness, loss of equilibrium, and a violent tonic-clonic convulsion</p> Signup and view all the answers

    Which neurotransmitter is normally released by most neurons of the substantia nigra in Parkinson's disease?

    <p>Dopamine</p> Signup and view all the answers

    Multiple Sclerosis is an autoimmune disorder.

    <p>True</p> Signup and view all the answers

    In Parkinson's disease, clumps of proteins in the surviving dopaminergic neurons of the substantia nigra are called ________.

    <p>Lewy Bodies</p> Signup and view all the answers

    What are the two defining characteristics of Alzheimer's disease?

    <p>Neurofibrillary tangles and amyloid plaques</p> Signup and view all the answers

    What is the main hypothesis regarding amyloid plaques in Alzheimer's disease?

    <p>Amyloid plaques are the primary symptom of the disorder and cause all the other symptoms.</p> Signup and view all the answers

    What is the most promising treatment approach for Alzheimer's disease mentioned in the text?

    <p>Immunotherapeutic approach with amyloid vaccine</p> Signup and view all the answers

    Neuroplastic changes underlying kindling are temporary.

    <p>False</p> Signup and view all the answers

    _______ refers to animals into which genes of another species have been introduced.

    <p>Transgenic</p> Signup and view all the answers

    What is transneuronal degeneration?

    <p>Degeneration that spreads from damaged neurons to neurons linked by synapses.</p> Signup and view all the answers

    What are the three possibilities for regeneration in the mammalian PNS following nerve damage?

    <p>All of the above</p> Signup and view all the answers

    Oligodendroglia, which myelinate CNS axons, promote and guide axon regeneration.

    <p>False</p> Signup and view all the answers

    Collateral sprouting is when axon branches grow out from adjacent healthy axons and synapse at the sites vacated by the degenerating ________.

    <p>axons</p> Signup and view all the answers

    What is neural reorganization in the context of cortical damage?

    <p>Changes in the organization of neurons following damage.</p> Signup and view all the answers

    What observation suggests that rapid reorganization in the brain never involves changes of more than 2 mm of cortical surface?

    <p>Two observations: reorganization often occurs too quickly to be explained by neural growth, and rapid reorganization never involves changes of more than 2 mm of cortical surface.</p> Signup and view all the answers

    What plays a role in the improvements observed after brain damage that do not result from true recovery of brain function?

    <p>Cognitive reserve</p> Signup and view all the answers

    Studies have shown that it may be possible to reduce brain damage by blocking neural ________ in human patients.

    <p>degeneration</p> Signup and view all the answers

    Enriched environments have been shown to decrease dendritic branching.

    <p>False</p> Signup and view all the answers

    Study Notes

    Phases of Neurodevelopment

    • Zygote: a single cell formed by the amalgamation of an ovum and a sperm that divides to form two daughter cells, then four, then eight.
    • Three other processes occur simultaneously:
      • Cell differentiation: cells become specialized (e.g., muscles, multipolar neurons).
      • Cell migration: cells move to their proper locations.
      • Cell-cell interactions: cells establish functional relationships with each other.

    Induction of the Neural Plate

    • Neural plate: a small patch of ectodermal tissue on the dorsal surface of the developing embryo, the first stage of neurodevelopment in all vertebrates.
    • Ectoderm → mesoderm → endoderm: the neural plate develops from the ectoderm.
    • Organizer: an area of the underlying mesoderm that sends chemical signals to induce the development of the neural plate.

    Neural Proliferation

    • Neural tube: the neural plate folds to form the neural tube, which eventually becomes the cerebral ventricles and spinal canal.
    • Ventricular zone: the region where most cell division occurs in the neural tube.
    • Proliferation patterns: different parts of the neural tube proliferate at different rates, leading to the characteristic shape of the brain.

    Migration and Aggregation

    • Migration: cells move to their target destinations.
    • Radial migration: cells move in a straight line outward from the ventricular zone.
    • Tangential migration: cells move parallel to the neural tube's walls.
    • Glia-mediated migration: glial cells guide migrating neurons.
    • Aggregation: neurons align with other developing neurons to form the nervous system's structure.

    Axon Growth and Synapse Formation

    • Axon growth: growth cones at the tip of axons extend and retract filopodia to guide growth.
    • Chemoaffinity hypothesis: each postsynaptic surface releases a specific chemical label that attracts growing axons.
    • Revised version: growing axons follow a series of chemical signals along the route.
    • Pioneer growth cones: the first growth cones to travel along a particular route, guided by guidance molecules.
    • Fasciculation: developing axons follow the paths established by preceding axons.

    Synapse Formation

    • Glial cells: particularly astrocytes, are necessary for synapse formation.
    • Synaptogenesis: the formation of synapses, which depends on the presence of glial cells.

    Neuron Death and Synapse Rearrangement

    • Neuron death: about 50% of neurons produced are eliminated, occurring in waves throughout development.
    • Apoptosis: active, programmed cell death, removing excess neurons in a safe and orderly way.
    • Synapse rearrangement: as neurons die, the space they leave is filled by the sprouting axon terminals of surviving neurons.

    Postnatal Cerebral Development in Human Infants

    • Brain growth: the brain's volume quadruples between birth and adulthood.
    • Synaptogenesis: a major burst of synaptogenesis occurs in the human cortex shortly after birth.
    • Myelination: increases the speed of axonal conduction, and its pattern parallels functional development.
    • Dendritic branching: progresses from deeper to more superficial layers, and can reconfigure quickly.

    Development of the Prefrontal Cortex

    • Prefrontal cortex: involved in working memory, planning, inhibiting responses, and following social rules.
    • Development: young children do not demonstrate these cognitive functions until the prefrontal cortex has developed.
    • Piaget studies: infants between 7 and 12 months exhibit perseveration errors due to underdeveloped prefrontal cortex.### Neurodevelopment and Experience
    • Permissive experiences are necessary for information in genetic programs to be manifested.
    • Instructive experiences contribute to the direction of development.
    • Experience has a time-dependent effect on development, with critical periods and sensitive periods.
    • Critical periods: essential for an experience to occur within a particular interval to influence development.
    • Sensitive periods: experiences have a great effect on development when they occur during a particular interval, but can still have weak effects outside the interval.

    Early Studies of Experience and Neurodevelopment

    • Research focused on sensory and motor deprivation and enrichment.
    • Sensory deprivation: reduced synapses and dendritic spines in primary visual cortex, and deficits in depth and pattern vision.
    • Enrichment: thicker cortex, more dendritic spines, and more synapses per neuron.

    Competitive Nature of Experience and Neurodevelopment

    • Depriving one eye of input for a few days early in life has a lasting adverse effect on vision in the deprived eye.
    • Ocular dominance columns in layer IV of the primary visual cortex are almost fully developed at birth.
    • Monocular deprivation changes the pattern of synaptic input into layer IV of the primary visual cortex.
    • If just one eye is deprived of light for several days, the system is reorganized.

    Effects of Experience on Topographic Sensory Cortex Maps

    • Three demonstrations:
      • Surgically altered axons of ferret's retinal ganglion cells to synapse in the medial geniculate nucleus of the auditory system.
      • Raised barn owls with vision-displacing prisms over their eyes.
      • Early music training influences the organization of human cortex.

    Experience Fine Tunes Neurodevelopment

    • Neurons begin to fire spontaneously and interact with the environment before the nervous system is fully developed.
    • The resulting neural activity fine-tunes subsequent stages of neurodevelopment.

    Neuroplasticity in Adults

    • Neurogenesis in adults: new neurons are created in the rat hippocampus and olfactory bulbs.
    • Substantial neurogenesis is restricted to the olfactory bulbs and hippocampuses.
    • New neurons come from different places: subventricular zone of the lateral ventricles for olfactory bulbs, and dentate gyrus of the hippocampus for hippocampal neurons.
    • Enriched environments produce more new hippocampal neurons.
    • Aerobic exercise improves cognitive function in older adults.

    Effects of Experience on the Reorganization of the Adult Cortex

    • Experience in adulthood can lead to reorganization of sensory and motor cortical maps.
    • Examples: tinnitus, adult musicians who play stringed instruments.

    Disorders of Neurodevelopment

    • Autism:
      • Complex neurodevelopmental disorder.
      • Core symptoms: reduced ability to interpret emotions and intentions, reduced social interaction and communication, and preoccupation with a single subject.
      • Characteristics: 80% male, 50% with mental retardation, 35% with seizures.
    • Autism spectrum disorders:
      • Delayed development of language and social interaction.
      • Many display minor anomalies of ear structure.
    • Autistic savants:
      • Intellectually handicapped individuals displaying amazing cognitive or artistic abilities.
      • About 10% of individuals with autism display some savant abilities.

    William Syndrome

    • Neurodevelopmental disorder associated with mental retardation and a heterogeneous pattern of abilities and disabilities.
    • Patients are sociable, empathetic, and talkative.
    • Language skills are remarkable despite low IQs.
    • Cognitive strengths: verbal and social skills, music.
    • Cognitive weaknesses: spatial abilities.
    • Health problems: involving the heart.

    Brain Damage and Neuroplasticity

    • Causes of brain damage:
      • Brain tumors.
      • Cerebrovascular disorders: strokes.
    • Brain tumors:
      • Meningiomas: tumors that grow between the meninges.
      • Infiltrating tumors: grow diffusely through surrounding tissue.
    • Cerebrovascular disorders:
      • Strokes: sudden onset cerebrovascular disorders.
      • Infarct: area of dead or dying tissue produced by a stroke.
      • Penumbra: surrounding area of dysfunctional tissue.
      • Cerebral hemorrhage: bursting aneurysm.
      • Cerebral ischemia: disruption of blood supply to an area of the brain.

    Note: Please let me know if you would like me to make any changes or add anything.### Ischemia Induced Brain Damage

    • Takes a while to develop, with little or no evidence of brain damage immediately after a temporary cerebral ischemic episode
    • Does not occur equally in all parts of the brain, with susceptible neurons in certain areas of the Hippocampus
    • Mechanisms of damage vary from structure to structure within the brain, and astrocytes have been implicated in at least some areas

    Close Head Injuries

    • Brain injuries produced by blows that do not penetrate the skull are called closed-head injuries
    • Contusions involve damage to the cerebral circulatory system, producing internal hemorrhaging and a hematoma
    • Contusions can occur when the brain slams against the inside of the skull, resulting in blood accumulation in the subdural space
    • Contusions frequently occur on the side of the brain opposite the side struck by a blow, known as Contrecoup Injuries
    • A concussion is diagnosed when there is a disturbance of consciousness following a blow to the head, but no evidence of a contusion or other structural damage
    • The Punch Drunk Syndrome is a type of dementia and cerebral scarring observed in boxers and other individuals who experience repeated concussions

    Infections of the Brain

    • Encephalitis is inflammation of the brain, and can be caused by bacterial or viral infections
    • Bacterial infections can lead to the formation of cerebral abscesses, and are also the major cause of meningitis
    • Penicillin and other antibiotics can eliminate bacterial infections of the brain, but cannot reverse brain damage that has already been produced
    • Viral infections, such as rabies, have a particular affinity for neural tissue and can be fatal

    Neurotoxins

    • Toxic psychosis is a type of chronic insanity produced by a neurotoxin
    • Some drugs used to treat neurological disorders can have toxic effects, such as Tardive Dyskinesia (TD)
    • Endogenous neurotoxins can be produced by the body, with antibodies attacking particular components of the nervous system
    • Genetic factors can also play a role in neurotoxin-related disorders

    Genetic Factors

    • Most neuropsychological diseases of genetic origin are caused by abnormal recessive genes that are passed from parent to offspring
    • Inherited neuropsychological disorders are rarely associated with dominant genes, as they tend to be eliminated from the gene pool
    • Inherit one abnormal gene, but do not develop the disorder, and the gene is passed on
    • Down syndrome is an example of a genetic disorder, caused by an extra chromosome 21

    Programed Cell Death

    • Cell death is not an either-or situation, with some dying cells displaying signs of both necrosis and apoptosis
    • Apoptosis is a more adaptive form of cell death, occurring gradually and without inflammation
    • Necrosis is a quick and destructive form of cell death, leading to inflammation and damage to nearby cells

    Neuropsychological Diseases

    • Epilepsy is a chronic brain dysfunction characterized by recurrent seizures
    • Many seizures do not involve convulsions, and may involve subtle changes in thought, mood, or behavior
    • Diagnosis of epilepsy relies heavily on evidence from EEG, with associated with high EEG spikes
    • Some epileptics experience peculiar psychological changes just before a convulsion, known as epileptic auras
    • Partial seizures are a type of seizure that does not involve the entire brain, with specific behavioral symptoms depending on the location of the epileptic focus

    Parkinson's Disease

    • Is a movement disorder of middle and old age, affecting 1-2% of the elderly population
    • More prevalent in males, with initial symptoms that are mild but increase in severity with advancing years
    • Common symptoms include tremor, muscular rigidity, difficulty initiating movement, slowness of movement, and a masklike face
    • Seems to have no single cause, with faulty genes, brain infections, strokes, tumors, traumatic brain injury, and neurotoxins all implicated
    • Associated with widespread degeneration, particularly in the substantia nigra, with a loss of dopamine in the substantia nigra and striatum
    • Symptoms can be alleviated by injections of L-dopa, but the treatment is not permanent and has side effects

    Huntington's Disease

    • Is a progressive motor disorder of middle and old age, with a strong genetic basis and associated with severe dementia
    • The first sign is often increased fidgetiness, with rapid, complex, jerky movements of entire limbs as the disorder develops
    • Eventually, motor and intellectual deterioration become so severe that sufferers are incapable of feeding themselves, controlling their bowels, or recognizing their own children
    • There is no cure, and death typically occurs about 15 years after the appearance of the first symptoms

    Multiple Sclerosis

    • Is a progressive disease that attacks the myelin of axons in the CNS
    • Typically attacks young people, with microscopic areas of degeneration on myelin sheaths, eventually leading to damage to the associated axons
    • Is an autoimmune disorder, with the body's immune system attacking part of the body
    • Diagnosing MS is difficult, with the nature and severity of the disorder depending on a variety of factors, including the number, size, and position of the sclerotic lesions
    • Common symptoms include visual disturbances, muscular weakness, numbness, tremor, and ataxia, with cognitive deficits and emotional changes in some patients

    Alzheimer's Disease

    • Is the most common cause of dementia, with a progressive decline in cognitive function
    • Can affect people as young as 40, with early stages often characterized by a selective decline in memory, deficits in attention, and other cognitive changes
    • The incidence of Alzheimer's is highest in regions far from the equator, with a possible link to vitamin D levels.

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    Description

    Learn about the phases of neurodevelopment, including the formation of zygote and cell differentiation, migration, and alignment.

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