The purpose of this study is to determine whether the non-daily administration of levodopa is effective in boosting semantic language acquisition in healthy subjects.

Our prior work using a between-subject design shows that daily administration of d-amphetamine or the dopamine precursor levodopa over the course of five days markedly improves word learning success in healthy subjects. In this randomized, placebo-controlled, double-blind clinical trial, we probe whether the effect can be replicated using a within-subject design, with administration of levodopa and placebo on alternate days for a total period of 10 days.

The expected scientific results will strengthen the basis for transferring neuromodulatory interventions from the laboratory to stroke patients with language dysfunctions. Because of the heterogeneity of stroke patients, only a within-subject design can be used to probe the effects of pharmacological adjuncts to language therapy.

Inclusion Criteria:

• Healthy subjects
• 20-35 years old
• Right handedness

Exclusion Criteria:

• Neurological/psychiatric/metabolic/cardiac disorders
• Asthma
• Known allergic reactions to one of the experimental drugs
• Other drugs affecting the central nervous system
• Leisure drug ingestion during the past 4 weeks (urine test)
• Smoking cessation during the past 2 weeks
• > 6 cups of coffee or energy drinks per day
• > 10 cigarettes per day
• > 50 grams of alcohol per day