At approximately day 1

Sulci begin to appear.

Reference

O’Rahilly R, Muller F. 1999. The embryonic human brain. An atlas of developmental stages. Second edition. New York: Wiley-Liss.

At approximately day 1

Secondary sulci are completed.

Duration: 12 weeks

Reference

Evans OB, Hutchins JB. 1997. Development of the Nervous System. Chapter 5 In: Haines DE, ed. Fundamental Neuroscience. New York: Churchill Livingstone.

At approximately day 1

Myelinogenesis begins and extends postnatally; it peaks between birth and the first year of life, and continues into adulthood.

Duration: 20 weeks

Reference [PubMed Link]

Herschkowitz N, Kagan J, Zilles K. 1997. Neurobiological bases of behavioral development in the first year. Neuropediatrics 28(6):296-306.