I suggest reading Chapter 3 of Joseph Farrell's Giants, Genes, Monsters, and Men, specifically part B of that chapter. It's all about the experiments and the technologies used by CIA for implanting, controlling, and removing memories and other stimulus in people's minds. It specifically mentions how this technology has been used to make people think that they communicated with aliens, and other crazier things. Here's an ebook copy https://mega.nz/#!j0s10YAS!dvueWbk93VjyqTGUEELcUJyviDNdLOG4x4ihxgCFmow
It's an epub file, so you'll need an ebook reader program to open it. Here's the installation file for Icecream Ebook Reader, one of the best I've found https://mega.nz/#!G1VwnQbA!sFTg_y6m24TL4xTTI7-LHtnh-CxkECrLWnGJt8sGD8Q