On the November 16, 2006 edition of Impact!, Kazarian, Matt Bentley, and Johnny Devine appeared with drastically changed appearances, calling themselves The New Movement. Later, through a series of vignettes, they revealed their name to be Serotonin, referencing the brain chemical of the same name that regulates, among other things, aggression, moodiness, and depression—things the Raven character has been linked to since its inception.
Raven's involvement with Serotonin began differently than with other groups he was leader of. Instead of speaking for the group during promos and being around at ringside during matches Raven is only seen after matches, when he comes to the ring to hit the members with a kendo stick, regardless of the result of the match, as part of a program referred to as "torture builds success". The members drop to their knees and take their licks without complaint, for the most part. The only dissension of being hit was that of Kazarian on occasion, however this was defused by the other members instead of Raven. Serotonin wrestled mostly on dark matches before Pay-Per-Views and lost the majority of them. When wrestling in singles competition, members often took the role of jobbers to more established stars such as Kurt Angle, Sting or Jerry Lynn. Serotonin picked up their first official win at Against All Odds 2007, defeating the team of Sonjay Dutt & Jay Lethal following interference from Maverick Matt. On the March 8, 2007 episode, it was announced that Raven had changed their names: renaming Kazarian to Kaz, Maverick Matt to Martyr, and Johnny Devine to Havok. Dissension on the part of Kaz became more apparent during the Lockdown 2007 pre-show, in which Kaz refused to allow Christy Hemme to be attacked by Raven after Serotonin's loss to VKM. Serotonin retaliated to this, distracting and therefore costing Kaz in a match against Chris Sabin on the March 31, 2007 episode of "Impact!". On the June 21, 2007 episode of Impact!, Kaz turned on Serotonin by costing Raven a match against Chris Harris. On the July 12, 2007 episode Kaz defeated Martyr and Havok in a 3-way match to earn a spot in the Ultimate X Match at Victory Road 2007. Kaz was subsequently attacked by Raven and the remaining members of Serotonin. Kaz defeated Raven in a match at Hard Justice. Bentley was later released by TNA, leaving only Havok and Raven as Serotonin members. Raven made few appearances in the succeeding months, some of which involved Raven and Havok aligning with Black Reign and James Mitchell, who were attempt to destroy Mitchell's longtime enemy and kayfabe son Abyss. On the November 15 edition of Impact, Havok was revealed to be Team 3D's X Division traitor and reverting to his Johnny Devine ring name, effectively ending Serotonin.
While the team was active, they competed in several pay-per-view pre-shows, often in losing efforts. They officially debuted as a team at Genesis 2006, in a losing effort against the Voodoo Kin Mafia. Serotonin only won twice on a pay-per-view event, albeit in dark matches, defeating Sonjay Dutt and Jay Lethal at Against All Odds 2007, after Martyr interfered, and Akira Raijin and Brute Issei at Victory Road 2007.