At the beginning of the Zerg portion of Starcraft: Brood War, Kerrigan tells you (a Cerebrate) that she "freed you from the control of the Overmind", and that she would let you live if you "served her willingly".
However there's no mention of the Cerebrates in Starcraft 2 (both Wings of Liberty and Heart of the Swarm) at all. Indeed:
the Cerebrates appear to be superseded by the Broodmothers, such as Zagara
Is there any canon reference as to whether the Cerebrates are still alive (or at least the one you control)?