Belongs to the norepinephrine-producing cell group.
Cell group A6 is located, one group on the right side and one on the left side, in the upper part of the pons. The noradrenaline-producing neurons are concentrated in the locus coeruleus , which is the noradrenergic center of the central nervous system.
The concentrated mass of norepinephrine-producing neurons in the locus coeruleus itself emits three offshoots:
1/ rostral into PAG (cell group A6cg),
2/ caudal as cell group A4 and
3/ ventrally in the form of the subcoerulic region (nucleus subcoeruleus, cell group A6sc).
The locus coeruleus along with its three offshoots is summarized as the "locus coeruleus complexet".