The brain controls the levels of hormones circulating in the blood. The fertility hormones are secreted in a pulsatile manner that is essential for normal reproduction in humans. While it is known that it is the brain that generates pulsatile hormone secretion, how it does this has remained a complete mystery. This projects aims to build on a recent exciting discovery in the laboratory that has given us a clue as to the origin of fertility hormone pulsatility. Using mouse models and the very latest techniques in neuroscience. we aim to elucidate and characterise the role of a small distinct group of brain cells we believe to be responsible for generating pulses of fertility hormones in the blood. Understanding how the brain controls fertility will lead to the development of new therapies for treating infertile couples in addition to new methods of contraception.