Human brain development timeline


Conception

Studies report that three primary structures are formed in the sixth gestational week. These are the forebrain, the midbrain, and the hindbrain, also known as the prosencephalon, mesencephalon, and the rhombencephalon respectively. Five secondary structures originate from these in the seventh gestational week. These are the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon; the lateral ventricles, third ventricles, cerebral aqueduct, and upper and lower parts of the fourth ventricle in adulthood originated from these structures. The appearance of cortical folds first takes place during 24 and 32 weeks of gestation.

Childhood and adolescence

Cortical white matter increases from childhood to adolescence, most notably in the frontal and parietal cortices. Cortical grey matter development peaks at ~12 years of age in the frontal and parietal cortices, and 17 years in the temporal lobes for women and they have reached full maturity at age 16-17. For men, they become fully mature at age 18. In terms of grey matter loss, the sensory and motor regions mature first, followed by other cortical regions. Human brain maturation continues to around 20 to 25 years of age.