Development of the human brain Wikipedia
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 from these in the seventh gestational week. These are the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon which later become the lateral ventricles, third ventricles, aqueduct, and upper and lower parts of the fourth ventricle from the telencephalon to the myelencephalon, during adulthood. Cortical white matter increases from childhood (~9 years) to adolescence (~14 years), 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 (with the superior temporal cortex being last to mature). In terms of grey matter loss, the sensory and motor regions mature first, followed by other cortical regions. One of the most intriguing facts of human brains is the appearance of cortical folds which first takes place during 24 and 32 weeks of gestation.