How the brain develops
The brain consists of nerve cells called neurons. Neurons arise in the prenatal phase before birth and are differentiated by chemical signals in order to specialize. The development process of neurons begins with the primitive parts of the brain and moves on to the more advanced parts after birth. The brainstem and midbrain that govern bodily functions like breathing, eating, sleeping, seeing, hearing, smelling and feeling are already very well developed at birth, while the higher regions such as the cerebral cortex and limbic system remain underdeveloped until the newborn phase.