Physio - Exam 3 Flashcards
(78 cards)
3 Perspectives on Brain Development
- As the brain develops, new behavior emerges.
- Emerging circuitry predicts behavioral development.
- Research investigates how language, injury, socioeconomic status impact brain structure & behavioral development.
Neurobiology of Development
Early development: all vertebrates appear similar.
Human embryos (day 28): forebrain, midbrain, hindbrain are visible.
Gross Development of the Nervous System
Day 15 Post-Fertilization: developing embryo takes shape. - Multiple cell layers.
- Embryonic Disc: Raised central area; the primitive body.
Neural Plate
The thickened region of the ectodermal layer that forms the neural tube.
Neural Groove
Shallow median groove found in the neural plate of an embryo.
Neural Tube
Structure in the early stage of brain development from which the brain and spinal cord develop.
How Do Stem Cells Know What to Become?
Stem cells receive instructions through molecular chats & epigenetic signals.
- Guide stem cells to transform into specific
cell types
- Their adaptability ensures our bodies can
grow, heal, and regenerate.
Neural Stem Cells
Self-renewing cells, that creates neurons & glia, lines the neural tube. When stem cells divide, it creates 2 stem cells. This stem cell process repeats all throughout life
- one that dies
- the other that lives to divide again
Subventricular Zone
Lining of neural stem cells surrounding the ventricles in adults.
Progenitor Cells
A precursor cell, originating from a stem cell, migrates and gives rise to either a neuron or a glial cell. It produces nondividing cells called neuroblasts and glioblasts.
Neuroblasts
Product of a progenitor cell that gives rise to different types of neurons.
Glioblasts
Product of a progenitor cell that gives rise to different types of glial cells.
Neurotrophic Factors
A chemical compound that promotes growth and differentiation in developing neurons and may also contribute to the survival of specific neurons in adulthood.
Growth & Development of Neurons
The human brain needs around 10 billion cells to create the cortex covering one hemisphere.
During peak prenatal brain development….
- Generates about 250,000 neurons per
minute.
- The brain prunes unnecessary cells and
connections.
- Adapting to an individual’s
experiences and requirements.
Cell Birth
Age 7 Weeks Post-Conception: A chemical compound aids the growth & specialization of developing neurons.
@ 5 months: this process is mostly finished; the hippocampus keeps producing new cells throughout life.
Initial 5 months of Pregnancy: the brain is better at handling injuries.
Cell Migration
Neurogenesis begins after the first neurons form. It lasts 6 weeks in the cortex and continues throughout life in the hippocampus. Damage during this process can be severe. Radial glial cells guide migrating neurons to their proper destinations.
Cell Differentiation
Neuroblasts transform into specific types of neurons post-cell migration & is mostly completed at birth. This process, also, continues for years in certain brain regions.
Cell Maturation
After neurons reach their destinations and differentiate into specific types, they mature in two ways:
1. Dendritic Growth: Neurons grow dendrites, increasing surface area for synapses with other cells.
2. Axonal Growth: - Neurons extend axons to appropriate targets, initiating synapse formation.
Synaptogenesis
Fully grown cerebral cortex, 1000s of synapses form through a genetic programming & environmental cue.
- 5th Gestational Month: simple synaptic contacts emerge.
- 7th Gestational Month: deep cortical neurons undergo synaptic development.
- After Birth: synaptic development accelerates rapidly during the first year of life.
Cell Death
The brain shapes itself by removing cells through cell death and synaptic pruning.
- Influenced by genetic signals, experience,
reproductive hormones, and stress.
- The cortex becomes thinner, following a back-
to-front gradient.
- Likely due to ongoing synaptic pruning.
Myelogenesis
Astrocyte and oligodendrocyte development occurs post-neurogenesis and persists lifelong, with oligodendroglia generating CNS myelin, serving as a cerebral maturation indicator.
Correlation with Behavior & Brain (Motor Development)
- Motor cortex neuron axons undergo myelination around the same time that the abilities to reach and grasp develop.
- Neurons in the motor cortex that regulate finger movements begin myelination when the pincer grasp skill starts to develop.
- Improved hand coordination in right-handed people is linked to thinner left motor cortex areas controlling the hand.
Correlation with Behavior & Brain (Language Development)
- Language development typically starts between 1 and 2 years of age.
- Most language acquisition is completed by age 12.
- Key neural changes during this period include:
- Increased dendritic complexity
- Enhanced interconnections
- Greater myelination in speech areas - Language development is not solely dependent on motor skills.
- Cell growth in language-specific brain regions is complete by age 2.
- From ages 2 to 12, the focus shifts to neuronal connectivity and myelination.
- Broca’s area undergoes significant axonal and dendritic growth between 15 to 24 months.
- This growth correlates with a rapid increase in vocabulary around age 2.
Correlation with Behavior & Brain (Cognitive Development)
- Children’s exploration and problem-solving evolve with cognitive growth.
- Brain development spurts, featuring more glial cells, blood vessels, myelin, and synapses.
- These growth spurts match Piaget’s stages, peaking at 14 to 16 years.
- Enable learning abilities like discrimination tasks at 12 months and memory tasks at 18 months.
- Reflects maturation of neural structures.