Ecstasy. Is it really such a bright idea? The brain scans in this photo show the sharp difference in human brain function for an individual who has never used drugs and one who used the club drug Ecstasy (XTC, MDMA, Adam, etc.) many times, but had not used any drugs for at least 3 weeks before having the scan. The left, bright reddish half shows active serotonin sites in the brain. Serotonin is a critical neurochemical that regulates mood, emotion, learning, memory, sleep, pain. The dark sections in the right half are serotonin sites that are not present even after 3 weeks without any drugs. In addition to these changes in serotonin sites, scientsts have found that Ecstasy injures serotonin neurons. Although these can regrow, they don't grow back normally and might not grow back in the right location.