sentences:  Next, endogenous contrast mechanisms were discovered by Detre, Koretsky, and colleagues was based on the net longitudinal magnetization within an organ, and a “second based on changes in the magnetic susceptibility induced by changing net tissue deoxyhemoglobin content”, which has been labeled BOLD contrast by Siege Ogawa.These discoveries served as inspiration for future brain mapping advancements.This allowed researchers to develop more complex types of experiments, going beyond observing the effects of single types of trials.