Autoradiography of SERT in baboon brain: sagittal section at level of cerebellum and brain stem. In control animal (top), there is high radioligand binding in dorsal brain stem. Less intense, but still significant, binding is seen in ventral and rostral brain stem. There is low but obvious binding in folia cerebelli. In MDMA-treated animal (bottom), binding is decreased in most of these areas, although small islands of high activity remain in dorsal brain stem. In MDMA-treated baboon, radioligand binding is almost completely absent in cerebellum. ROSTRAL and CAUDAL = axes of brain stem; Cb = cerebellum; IC = inferior colliculus; P = pons.