milestones in brain development

Question 1

development from 3-10 weeks

Answer 1

• 3 weeks eye formation
• 6 weeks – more flexures and swellings.
• 10w – cerebral expansion and commissures.

Question 2

development from 3-9 months

Answer 2

• 3m – basic structures established.
• 5m – CNS myelination begins. Continues to adolescence.
• 7m – lobed cerebrum.
• 9m – gyri and sulci.

Question 3

critical periods

Answer 3

• Abnormalities dependent on time of infection.
• 6th week - eye malformations – e.g. cataract.
• 9th week - deafness – organ of Corti.
• 5th to 10th weeks - cardiac malformations.
• CNS disorders in 2nd trimester.
• Risk falls after 16 weeks.

Question 4

fetal alcohol syndrome

Answer 4

• Alcohol crosses placenta.
• Fetus doesn’t clear alcohol well → Fetal levels higher.
• Facial abnormalities
• Microcephaly: Loss of cells, Loss fibres e.g. callosal agenesis, Disturbed migration
• Irritability
• Motor and intellectual impairment

Question 5

development of sensation

Answer 5

• Innervation of dermal skin from 28 weeks / subdermal from 6 - 8 weeks
• DRG connection to spinal cord from 8 weeks. Non - noxious.
• C – fibre (noxious stimuli) connection from 19+ weeks.
• Reflex response to noxious stimuli in 23 week preterm infants.
• Organised thalamus forms from 8+ weeks.
• Retinal inputs arrive at 14 – 16 weeks.
• Myelination from 25 weeks.
• Connections from the thalamus to cortex from 24 weeks. (Sub-plate 12+)