The Effects of Losartan on Reward Reinforcement Learning

The Role of the Renin-angiotensin System in Reward Reinforcement Learning

This study aims to investigate whether a single dose of losartan (50 mg) can affect learning from positive and negative outcomes and its related neural mechanisms.

Emerging evidence suggests that the renin-angiotensin system can impact dopamine (DA) transmission and its modulatory role in reward processing. For instance, recent animal models have found that the angiotensin antagonist losartan reduces rewarding effects of methamphetamine and nicotine by modulating DA release in the striatum.The present study thus will investigate losartan effects on reward reinforcement learning and the underlying neural mechanisms. In a double-blind, between-subject, placebo-controlled design, 60 healthy male subjects will be randomly assigned to receive single-dose losartan (50 mg) or placebo, 90 minutes before performing a probabilistic reinforcement learning task during fMRI.

Inclusion Criteria:

• Healthy subjects without past or current psychiatric or neurological disorders
• Right-handedness
• Normal or corrected-normal version

Exclusion Criteria:

• History of head injury
• Medical or psychiatric illness
• Hypertension
• General cardio-vascular alteration or diseases
• Allergy against medications
• Visual or motor impairments
• Claustrophobia
• Drug addiction
• Nicotine dependence
• FMRI contradictions