Haloperidol affects choice and changes preference: the barrier choice paradigm

Abstract

Controversial results have been generated in the study of neuroleptic drugs (e.g. haloperidol). One research line maintains that neuroleptics impair the functioning of the motor system. Another line suggests that these drugs take away the hedonic effect of positive reinforcers, implying an anhedonic model. A third alternative says that dopamine helps the organism to overcome the obstacles it faces in the environment. By blocking dopamine receptors (D2) haloperidol changes choices, driving preference in favor of alternatives requiring minimal effort, even though they are providing a less preferred food. The present paper reports data collected in our laboratory with rats responding to a choice situation with multiple alternatives and complex locomotion required to travel from one site to another. The results show that in the available alternatives haloperidol changed time allocation and response distribution, but it did not interfere with the discrimination that rats established between rich and lean alternatives, nor did it extinguish the behavior of pressing a lever to obtain food reinforcers. These results have implications for the generality of the anhedonic model.