Dorsal-Ventral Patterning in the Brain
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Questions and Answers

What is the process where the axon needs to know what direction it needs to take called?

  • Axonogenesis
  • Repulsion guidance
  • Chemoattraction
  • Axon guidance (correct)
  • Which molecules attract the axon during the process of axon guidance?

  • Ephrin
  • Neurotrophic factors
  • Netrin (correct)
  • CAMs
  • What allows axons to grow together and form fasciculations?

  • CAMs (correct)
  • Synaptogenesis
  • White matter tracts
  • Neurotrophic factors
  • What do pre-synaptic and post-synaptic neurons use to communicate during synaptogenesis?

    <p>Neurotrophic factors</p> Signup and view all the answers

    Which molecules allow axons to form white matter tracts after becoming myelinated?

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

    What is the role of growth cone at the tip of the axon during axon guidance?

    <p>Detecting environmental molecules</p> Signup and view all the answers

    What is the main responsibility of Sonic hedgehog (Shh) signalling molecule in the brain?

    <p>Expression of neurones in the ventral aspect</p> Signup and view all the answers

    Which type of neurons are associated with Parkinson's Disease due to their death?

    <p>Dopaminergic neurons</p> Signup and view all the answers

    Which axis determines the basic plan for the location of neurones in the brain?

    <p>Dorsal-ventral axis</p> Signup and view all the answers

    What happens when there is an interruption to the dorsal-ventral axis in the brain?

    <p>Neurones end up in the wrong place</p> Signup and view all the answers

    When cortical layering does not work properly, what is the likely outcome?

    <p>Interruption to function</p> Signup and view all the answers

    In which part of the brain do we observe more advanced organization characterized by identifiable layers?

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

    What is the main function of the dorsal-ventral patterning in the brain?

    <p>Controlling the migration of neurones to the right layer</p> Signup and view all the answers

    Which layer is adjacent to the white matter in a fully formed brain?

    <p>Layer 6</p> Signup and view all the answers

    What is the role of signalling molecules in neuronal organization within regions/nuclei?

    <p>Guiding the neurones to the correct layer</p> Signup and view all the answers

    What may be a consequence of abnormal neuronal migration in the brain?

    <p>Misplacement of neurones within layers</p> Signup and view all the answers

    Which process involves neurones starting to become functioning cells?

    <p><strong>Differentiation</strong></p> Signup and view all the answers

    What is one potential impact of exposure to Zika virus on a developing brain?

    <p><strong>Microcephaly due to fewer neurones</strong></p> Signup and view all the answers

    Study Notes

    Brain Development and Structure

    • Different layers of the brain have varying densities of neurons, with each purple dot representing a nucleus.
    • The size of cell bodies also varies across layers.

    Cortical Layering

    • The inner layer (layer 6) is adjacent to the white matter in a fully formed brain, but adjacent to the ventricles in the early stages of brain development.
    • Cells in layers 1-6 originate from a strip of cells adjacent to the fluid-filled vesicle in the early brain.

    Process of Cortical Layering

    • Proliferation: Neurons proliferate at a high rate to populate the entire cortex, occurring at a rate of 250,000 cells per minute in the ventricular zone.
    • Migration: Neurons migrate to the correct layer, involving signaling and scaffolding.
    • Differentiation: Immature neurons differentiate into functioning neurons, forming dendrites, axons, ion channels, and NT receptors.

    Abnormalities in Cortical Layering

    • Abnormalities in proliferation can result in fewer neurons and a smaller brain (microcephaly), e.g., exposure to Zika virus during pregnancy.

    Axon Guidance and Connection Formation

    • Axons use growth cones to detect molecules in the environment, with chemoattractants attracting and repellents repelling them.
    • Axons stick together via cell adhesion molecules (CAMs), forming fasciculations, and eventually white matter tracts.
    • Synaptogenesis involves two-way signaling between pre-synaptic and post-synaptic neurons, with communication via neurotrophic factors (e.g., NGF).

    Dorsal-Ventral Patterning

    • Signaling molecules (e.g., Sonic hedgehog) determine the dorsal or ventral location of neurons in the brain.
    • Examples of neurons in the ventral aspect of the brain include motor neurons of cranial nerves, dopaminergic neurons, and serotonergic neurons.

    Basic Plan of Neuron Location

    • The location of neurons is determined by their position in the anterior-posterior, dorsal-ventral, and medial-lateral axes.
    • Any interruption to this plan can result in neurons ending up in the wrong place.

    Organization Within Regions/Nuclei

    • The basic plan works well for subcortical structures, but cortical organization is more advanced, with identifiable layers and varying densities and types of neurons.
    • Cortical layering is essential for proper function, and disruptions can lead to functional interruptions.

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    Description

    This quiz explores the signals that determine whether neurones are located in the dorsal or ventral part of the brain, with a focus on the Sonic hedgehog (Shh) signalling molecule. Topics covered include the expression of neurons in different brain regions and their association with neurological conditions such as Parkinson's Disease.

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