The main objective of our study is to test if changes in the metabolism of brain dopamine can be conditioned. The metabolism of dopamine in brain is known to be altered by drugs. Associating these alterations of dopamine metabolism with conditional stimuli (sounds) in the environment can lead to conditioned reflex alteration of brain dopamine metabolism. Conditioning of brain dopamine was first reported by Perez-Cruet (Drug Addiction. Ed. H. Lal, Vol. 3: 249-250, 1974 and Pav. J. Biol. Science 11: 237-250, 1976). More recently others have partially confirmed these original reports. NIMH grant supported research confirms the feasibility of conditioning of dopamine metabolism to droperidol a short-acting butyrophenone. Recent data suggests that the conditioning of brain dopamine metabolism involves a counter conditioning process defined as critical conditioning. In addition recent unpublished findings suggest pre-synaptic as well as post-synaptic receptor involvement in the conditioning of brain dopamine metabolism. The results indicate that environmental factors can condition the metabolism of neurotransmitters in the brain or that the metabolism of the brain can adjust to environmental factors through a conditioning process.