Chapter 8 - Neurodevelopment and adaptation Flashcards
(33 cards)
What’s the purpose of the Tower of Hanoi test?
- Used to test planning skills
- Also an indicator of frontal lobe development
How does lower SES correlate to brain development?
- It’s associated with decreased cortical surface area in widespread regions on frontal, temporal, and parietal lobes
How is Darwin’s view supported concerning embryos and evolution?
- Since all embryos of different species closely resemble one another, it supports the idea that all vertebrates arose from a common ancestor
What are the three chambers of the vertebrate brain?
- Forebrain (cerebrum), midbrain and hindbrain (both are found in the brainstem.
Neural plate vs. Neural tube?
- Neural plate - primitive neural tissue that gives rise to the neural tube
- Neural tube - Structure in early development from which the brain and spinal cord arise
When do gyri and sulci start to appear?
- Around seven months
- By nine months, it resembles an adult brain
What are stem cells?
- Unspecialized cells that can reproduce itself indefinitely and differentiate into more than one type of specialized cells
What are the different types of stem cells?
- Totipotent/omnipotent - the most undifferentiated, make up the zygote and cells of the first two divisions, give rise to embryonic cells and placenta
- Pluripotent - Can differentiate into all embryonic cell types, but not placenta, also called embryonic stem cells
- Multipotent - Can differentiate into multiple specialized cell types found in specific tissues/organs (ex. bone marrow, neural stem cells)
- Unipotent - form a single lineage of cell types and are constantly renewing themselves (ex. Spermatogonial stem cells)
What’s a progenitor cell?
- Precursor cell derived from a stem cell that migrates and produces a neuron or glial cell
What’s a neuroblast and a glioblast?
- Neuroblast - Product of a progenitor cell that gives rise to different neuron types
- Glioblast - Product of a progenitor cell that gives rise to different glial cells
What are the 7 stages of brain development?
1) Cell birth (neurogenesis)
2) Neural migration
3) Cell differentiation
4) Neural maturation (dendrite and axonal growth)
5) Synaptogenesis
6) Cell death and synaptic pruning
7) Myelogenesis (mainly in adulthood)
*Stages 4-7 continue well after birth
When do neurogenesis, neuronal migration, and neuronal maturation occur?
- Neurogenesis: 6-25 weeks
- Neuronal migration: 8-29 weeks
- Neuronal maturation: 20 weeks till birth
What role do the subventricular zone and the radial glial cell body play in neuronal migration?
- Subventricular zone - Where neuronal stem cells self-populate
- Radial glial cell body - act as scaffold for migrating neuronal cells. Migrating neurons end up climbing up these cells
What two types of signals monitor and specify cell fate during the differentiation stage?
1) Intrinsic: Inherited from mother cell (physically separated and given to daughter cell)
2) Extrinsic: Chemical cues received from cell’s surroundings
- Together these help restrict the choice of traits a cell can express
When does cell maturation occur?
- Takes place after neurons have migrated to their proper destination and have differentiated.
- Begins prenatally, but continues well after birth
What two major actions occur during the maturation stage?
1) Dendritic growth - Helps provide SA for synapses with other cells. This is called arborization (very slow process)
2) Axonal extension - Helps appropriate targets to initiate synapse formation (very fast process)
What is autism spectrum disorder characterized by?
- Occurs via accelerated rates of neuronal maturation, leading to excessive brain volumes in areas such as the amygdala, temporal and frontal lobes
- More common in boys
- Don’t really know what causes it
How does axonal guidance/axonal pathfinding occur?
- Happens during the maturation phase
- the growing tips of axons are called growth cones
- Growth cones are responsive to two types of molecules.
What are the two types of molecules that guide growth cones?
1) Cell adhesion molecules (CAMs) - manufactured by other cells and attached directly to the substrate along which the growth cones move
2) Tropic molecules - they are secreted and diffusible and will form a concentration gradient that either attracts or repels pathfinding neurons (chemoattraction or chemorepulsion)
Which area of the brain has extensive synaptogenesis shortly after birth?
- The primary visual cortex (V1)
- The synaptic density doubles between 2-4 months and increases until 1 year of age
How does the brain ‘chisel’ itself?
- Genetic signals, experience, reproductive hormones, stress, SES
- The cortex becomes thinner in a caudal-rostral gradient (back to front)
What’s neural Darwinism?
- Processes of cell death and synaptic pruning are the outcome of competition among neurons for connections and metabolic resources in an aneural environment
- Neurons are dependent upon postsynaptic targets for survival
- These target cells produce neurotrophic factors regulating survival of the presynaptic cell
- Lack of neurotrophic factors leads to apoptosis (programmed cell death)
T/F: Radial glia differentiate into astrocytes once neural migration is complete while oligodendrocytes myelinate axons.
- TRUE
What’s a useful index of cerebral maturation?
- The myelination of axons via oligodendrocytes
