What happens in the brain of a person that progressively loses control over his/her drug consumption and develops addiction? Our research work aims to provide answers to this question. Within this context, we study some of the variables that influence the risk of becoming addicted to drugs. Amongst these variables are pharmacokinetic variations (for example, how fast a drug reaches the brain, how brain levels of drug fluctuate during a bout of intoxication), and exposure to psychiatric medications, namely antipsychotic drugs. How do the kinetics of drug administration change the drug’s effects on brain and behaviour? Do antipsychotic medications — all of which act on the brain’s reward system — have effects that could make drugs of abuse seem more attractive? We combine animal models of drug self-administration with pharmacological and molecular biology techniques to answer these questions.