When our neurons—the principle cells of the brain—die, so do we.

Most neurons are created during embryonic development and have no “backup” after birth. Researchers have generally believed that their survival is determined nearly extrinsically, or by outside forces, such as the tissues and cells that neurons supply with nerve cells.

A research team led by Sika Zheng, a biomedical scientist at the University of California, Riverside, has challenged this notion and reports the continuous survival of neurons is also intrinsically programmed during development.