CNS Development Flashcards
when does human brain development occur?
in the 3rd post conception week and continues well into late adolescence/early adulthood and beyond
how do genes influence the brain?
determine
- correct sequence and evolution of the brain from conception to neuronal proliferation, migration and reorganisation
- development of dendritic and axonal interconnections
- development of synapses, receptors and neurotransmitters
what can affect the intrauterine environment?
maternal health and disease (e.g maternal PKU) insults during pregnancy (continuous/episodic) placental function and fetal nutrition
what can affect the extra-uterine environment?
physical factors - nutrition, environmental toxins
emotional and social factors (neglect etc)
exposure to drugs, alcohol etc
what are the stages in brain development?
embryonic period (conception - week 9)
fetal development (week 9 - 40/42)
post natal development adolescent brain
describe 5 features of the embryonic period?
2 layered embryo
epiblast and hypoblast
primitive streak and primitive node
migration of cells through streak then rostral-caudal migration
determined by nodal signalling
what does the ectoderm develop into during gastrulation?
skin hair nails neural tissue
what does the mesoderm develop into?
muscle bone cartilage vascular system
what does the endoderm develop into?
gut and respiratory system
how does the neural tube develop?
first neural structure to develop occurs at 20-27 days
first neural progenitor cells form the neural plate then becomes neural groove then becomes neural tube then becomes neural crest
what does the neural tube develop into?
neural progenitors line the inside of the neural tube (called the ventricular zone)
the hollow centre of the tube will become ventricular system and central channel of the spinal cord
anterior/rostral tube will become the brain caudal tube will become the spinal cord
what are the 3 primary brain vesicles from top to bottom?
prosencephalon (forebrain) mesencephalon (midbrain) rhombencephalon (hindbrain)
what are the 5 secondary brain references?
telencephalon (from forebrain)
diencephalon (from forebrain)
mesencephalon (from midbrain)
metencephalon (from hindbrain)
mylencephalon (from hindbrain)
what is the hypoblast?
lateral to developing endoderm will eventually be taken over by endoderm as it spreads
what is the epiblast?
will become ectoderm
how many layers in the embryonic period?
2
how many layers in gastrulation?
3 - ectoderm - mesoderm - endoderm
when do the primary brain vesicles develop?
3-4 weeks
when do the secondary brain vesicles develop?
5 weeks
what is neural patterning?
the biological process by which cells in the developing nervous system acquire distinct identities according to their specific spatial positions occurs in embryonic period sets stage for later development
give an example of neural patterning?
neocortical patterning neocortex has distinct functional and structural areas
- anterior/rostral
- posterior/caudal
what are the 2 signalling molecules in the neocortex and how are they significant?
Emx2 and Pax6
- high concentration of Pax6 and low Emx2 which induces progenitor cells to differentiate into motor neurons at the posterior/caudal area
- low Pax6 and high Emx2 which induces visual and cortical neurons development at the anterior/caudal area
what happens during the fetal period?
smooth brain (lissencephalic) develops its characteristic folded appearance (sulci and gyrus) happens from week 9 to term
when do the primary, secondary and tertiary sulci develop in the brain?
primary = 8-26 weeks
secondary = 30-35 weeks
tertiary = week 36 onwards into early infancy
