PSY2061 Lecture Notes - Lecture 1: Apoptosis, Adult Stem Cell, Subventricular Zone
5 Jun 2018
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PSY2061 – Lecture – Week 1
~ human brains
• 86 billion neurons
• 1.5 kg
• first 100 days are most crucial - setting the foundation for all
subsequent brain maturation - conception to 2 years
• functional networks formed by connections with hubs of neurons
• neuroplasticity is greatest during early development
•
o responds according to genetic programs and environment
• events during early development can result in major consequences
~ neurodevelopment
• complex, dynamic process
• involves a precisely orchestrated sequence of events influenced by
•
o genetic
o environmental
o biochemical
o physical events
~ fetal development
• zygote - first cell - 2 daughter cells - 4 cells etc
• cells must differentiate
• cells must form connections with other cells to establish functional
capacity
• cell specialisation
•
o totipotent - any type
o pluripotent -
o multipotent
o unipotent
~ phases of neurodevelopment
• induction of the neural plate
•
o plate - groove - tube - tube becomes CNS
• neural proliferation
•
o rapid cell division/formation
o occurs rapidly after neural tube is formed
o occurs at the ventricular zone
o process controlled by chemical signals
o cells migrate away from the ventricular zone
• migration
•
o process by which cells travel to their target location
o determined by time and location - around ventricular zone
o
▪ precise and predictable schedule
o two types of migration
o
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▪ radial - ventricular zone outward to outer wall
▪ tangential - parallel to outer wall
▪ combination
o methods of migration
o
▪ somal translocation
▪
▪ migrating cell grows an extension
▪ extension explores immediate environment for
attractive and repulsive cues
▪ glia mediated migration
▪
▪ neurons travel along glial cells
▪ guidance molecules
▪
▪ chemicals guide migrating neurons by attracting or
repulsing them
o progresses from deeper layers to more superficial layer
• aggregation
•
o once migrated - neurons align themselves with other neurons to
form CNS structures - with similar function
o cell adhesion molecules are located on the surface of cells
• axon growth and synapse formation
•
o axons and dendrites emerge from neurons
o projections grow towards their target
o growing tip of axons/dendrites have growth cones
o
▪ extensions that extend and retract called filopodia -
searching for correct route and target
▪ pioneer growth cones - first growth cones travelling the
route
▪
▪ identifies correct route by interacting with guidance
molecules
▪ subsequent axons follow the same path -
fasciculation
o chemoaffinity hypothesis
o
▪ postsynaptic surface - dendritic arms - release a specific
chemical label which attracts selective growing axons to the
target
▪ however - axons do not always grow directly to its target
▪ revised
▪
▪ growing axon not attracted to target by a single
chemical released at target site
find more resources at oneclass.com
find more resources at oneclass.com
