The influence of white noise and dopamine on language learning in healthy young adults.

Arm 1: Pharmacological manipulation of dopamine (i.e., ingestion of one Madopar tablet of 125mg). Arm 2: No pharmacological manipulation of dopamine (i.e., ingestion of a placebo tablet containing an inactive substance). The intervention drug (i.e., Madopar) will contain two active substances: 100mg of levodopa and 25mg of benserazide. The placebo tablet will contain an inactive substance: 125mg of After ingesting either the Madopar tablet or placebo tablet, participants will be asked to complete an in-scanner new word learning task where half of the words (20 out of 40 new words) will be learned with auditory white noise being delivered through headphones (at approximately 70 dB on top of background scanner noise) and half of the words (20 out of 40 new words) will be learned without auditory white noise being delivered (i.e., only background scanner noise). A counterbalanced order will be used, with half of the participants in both arms learning the first block of 20 new words with white noise and the other half of the participants in both arms learning the second block of 20 new words with white noise. The in-scanner new word learning task will take approximately 50 minutes to complete, with the first 25 minutes used to learn the first block of 20 new words (with white noise or not) and the last 25 minutes used to learn the second block of 20 new words (with white noise or not). In both blocks, participants will have 3 exposures to the 20 new words, and after each exposure, participants will complete an in-scanner recognition task to test their learning. All participants will experience all 3 exposures. Each exposure will consist of seeing the 20 new words paired with a picture, one at a time for 5 seconds. Participants will receive $1 for each new word correctly learned. Staff involved in recruitment and delivery of the intervention include a clinical nurse, radiographer, radiologist, speech pathologist, post-doctoral research fellow and research assistant. The intervention session will be conducted at the Herston Imaging Research Facility in Brisbane, Australia.