- Positron emission tomographic analysis of central D1 and D2 dopamine receptor occupancy in patients treated with classical neuroleptics and clozapine. Relation to extrapyramidal side effects. Farde, L., Nordström, A.L., Wiesel, F.A., Pauli, S., Halldin, C., Sedvall, G. Arch. Gen. Psychiatry (1992)