An element is a pure substance that is made from a single type of atom. Elements are the building blocks for all the rest of the matter in the world. Examples of elements include iron, oxygen, hydrogen, gold, and helium.
Since the initial discovery that the adult brain contains stem cells that generate new neurons, an important question in neurobiology has been whether or not this adult neurogenesis is functionally important.
Neurogenesis occurs during embryogenesis in all animals and is responsible for producing all the neurons of the organism. Prior to the period of neurogenesis, neural stem cells first multiply until the correct number of progenitor cells is achieved.