Development of the CNS Flashcards
When does human brain development begin?
In the third post conception week
What does the information carried in genes determine once it is decoded?
Correct sequence and evolution of brain development
Development of dendritic and axonal interconnections
Development of synapses, receptors and neurotransmitters
What determines the intrauterine environment?
Maternal health and disease (ie maternal PKU)
Insults (i.e alcohol exposure, cytomegalovirus)
Placental function and foetal nutrition
What determines the extrauterine environment?
Physical factors = nutrition, environmental toxins
Emotional and social factors = neglect
Exposure to drugs, alcohol and other related substances
When is the embryonic period?
Conception to week 9
When does foetal development occur?
From week 9 until week 40/42
What are the different phases of development?
Embryonic period, foetal development, postnatal development, adolescent brain
What is the embryo like structurally in the embryonic period?
2 layered embryo, epiblast and hypoblast, primitive streak and primitive node
What occurs during the embryonic period?
Migration of cells through the primitive streak then rostral-caudal migration = determined by nodal signalling
What does gastrulation result in?
The development of a three layered embryo = ectoderm, mesoderm, endoderm
What does the ectoderm go on to form?
Skin. nails, hair, neural tissue
What does the mesoderm form?
Muscle, tone, cartilage and the vascular system
What systems in the body are formed from the endoderm?
The gut (GI) and respiratory systems
What is the first well-defined neural structure to form?
The neural tube = occurs at day 20-27
What do neural progenitor cells form in the neural tube?
The neural plate = line the inside of the neural tube
What is the ventricular zone?
The inside of the neural tube that is lines with neural progenitor cells
What does the hollow centre of the neural tube go on to form?
The ventricular system and central channel of the spinal cord
What does the brain form from in a foetus?
The anterior/rostral tube of the neural tube
What does the caudal tube of the neural tube go on to form?
The spinal cord
When does neural patterning begin?
During the embryonic period = sets the stage for later development
Is neural patterning an ongoing process?
Yes = undergoes continual and complex refinement
What does the mature neocortex have?
Distinct functional and structural areas
What are the signalling molecules present in the neocortex?
Emx2 and Pax6
What does a high concentration of Pax6 with a low concentration of Emx2 in the neocortex cause?
Induces progenitor cells to differentiate into motor neurons
What causes the induction of visual cortical neurons?
Low concentrations of Pax6 with high concentrations of Emx2 in the neocortex
What is the initial appearance of the brain at the beginning of the foetal period?
Smooth in contour (lissencephalic) = gradually develops folded appearance (sulcal and gyral pattern)
When do primary sulci form?
From week 8 to week 26
What are some examples of primary sulci of the brain?
Longitudinal fissure, sylvian sulci, cingulate sulci, parieto-occipital and calcarine sulci, temporal sulci
When do the secondary sulci form?
From week 30 until week 35
When do the tertiary sulci form?
From week 36 and into the postnatal period
Why is the development of sulci and gyri required?
To accommodate the proliferating neuronal populations
How do neuronal progenitor cells in the ventricular zone divide initially during the foetal period?
Symmetrically = two identical progenitor cells arise following division
What follows symmetrical neuronal progenitor cell division in the foetal period?
Asymmetrical neuronal progenitor cell division = produces one progenitor cell and one neuron