L-Dopa improves learning and maintenance of new nouns in healthy adults
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1
The University of Queensland, UQ Centre for Clinical Research & School of Health and Rehabilitation Sciences, Australia
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2
The University of Queensland, School of Health & Rehabilitation Sciences, Australia
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3
The University of Queensland, UQ Centre for Clinical Research, Australia
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4
The University of Queensland, Centre for Advanced Imaging, Australia
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5
The University of Queensland, Asia Pacific Centre for Neuromodulation, Australia
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6
Cambridge University, Psychiatry, United Kingdom
Background: L-Dopa is a dopamine precursor that has been shown to improve implicit word learning in healthy adults. L-Dopa has also been shown to modulate semantic processing and enhance semantic salience, which may be of relevance to mechanisms of new word learning. The present study aimed to investigate whether augmenting brain dopamine levels with L-Dopa would enhance new word learning in healthy adults. We also sought to evaluate whether words paired with semantic information would be learnt more effectively than words paired with non-semantic information, and whether L-Dopa would enhance this process.
Methods: 21 (12 female) healthy young adults participated in an initial word learning session. Prior to the learning session, each participant received either L-Dopa (as Madopar 125mg) or placebo in a double-blind randomised design. Participants learned written names for 20 pictures of novel aliens, with each name consisting of a legal nonword and either two adjectives (the semantic condition) or two uncommon surnames (the non-semantic condition). Written recall and multiple-choice recognition of the new names was tested periodically during the learning session, and at a follow-up session 7-10 days later.
Results: Participants who had taken L-Dopa prior to learning exhibited higher recall accuracy during the learning session and at follow-up than those who had taken placebo. There was no influence of learning condition (Semantic or Non-Semantic) on recall accuracy at either timepoint. However, there was an influence of learning condition on recognition accuracy at the follow-up session, with the L-Dopa group displaying greater accuracy for stimuli in the semantic condition than the placebo group. This effect was not observed for stimuli in the non-semantic condition.
Conclusions: L-Dopa improved the speed and success of new word learning, and also improved retention of the new words. The difference observed in recognition performance between the two groups at follow-up suggests that the influence of increased dopamine on the consolidation of new lexical representations is enhanced by semantic information during encoding.
Keywords:
Dopamine,
Language,
Memory,
semantics,
word learning
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Poster
Topic:
Memory and Learning
Citation:
Copland
D,
Campbell
A,
Rawlings
A,
McMahon
K,
Silburn
P and
Nathan
P
(2015). L-Dopa improves learning and maintenance of new nouns in healthy adults.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00165
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Prof. David Copland, The University of Queensland, UQ Centre for Clinical Research & School of Health and Rehabilitation Sciences, Brisbane, Australia, d.copland@uq.edu.au