The inner environment of protoplanetary disks with near infrared spectro-interferometry

In this paper, I review how optical spectro-interferometry has become a particularly well suited technique to study the close environment of young stars, by spatially resolving both their IR continuum and line emission regions. I summarize in which ways optical interferometers have brought major insights about our understanding of the inner part of circumstellar disks, a region in which the first stages of planet formation are thought to occur. In particular, I emphasize how new methods are now enabling to probe the hot gas emission, in addition to the circumstellar dust.