i know this post is kind of regular since im not citing medical sources, but this is pretty much the gist.
turkeylurkey, if you would prefer citations ill try and find them for you, but here is pretty much what i have found to be the argument against E creating "holes in the brain":
The “holes in the brain” scan conducted on MDMA users does not reveal actual physical holes or missing tissue in the brain. What it reveals is blood flow activity, and the “holes” represent areas in the brain where less blood is present or traveling. Of course, this means that in those particular areas, serotonin chemicals, serotonin receptor sites, neurotransmitters, and other parts of normal brain functions are not as active as they should be. Such a lack of blood flow can be caused, however, by anything as simple as staying up all night, meaning a brain scan conducted on just a weary person can reveal “holes” in some areas of the brain. Keep in mind the possibility that the MDMA users who had their brains scanned may have been poly-drug users, and the potential effects of those other drugs on their brains. There is also no conclusive data yet to suggest that the decreased blood flow will never pick up again. There have been no human studies yet to prove that the brain damage caused by MDMA will remain permanent, or how problematic such damage may be on the person's daily function.
http://www.leshengliu.com/Drug%20Publications%20Ecstasy%20Debunking%20Myths.html