Shellshear Leanne, MacDonald Anna D, Mahoney Jeffrey, Finch Emma, McMahon Katie, Silburn Peter, Nathan Pradeep J, Copland David A
UQ Centre for Clinical Research, The University of Queensland, Brisbane, Australia.
School of Health and Rehabilitation Sciences, Division of Speech Pathology, The University of Queensland, Brisbane, Australia.
Hum Psychopharmacol. 2015 Sep;30(5):341-9. doi: 10.1002/hup.2480. Epub 2015 Apr 21.
While the role of dopamine in modulating executive function, working memory and associative learning has been established; its role in word learning and language processing more generally is not clear. This preliminary study investigated the impact of increased synaptic dopamine levels on new-word learning ability in healthy young adults using an explicit learning paradigm.
A double-blind, placebo-controlled, between-groups design was used. Participants completed five learning sessions over 1 week with levodopa or placebo administered at each session (five doses, 100 mg). Each session involved a study phase followed by a test phase. Test phases involved recall and recognition tests of the new (non-word) names previously paired with unfamiliar objects (half with semantic descriptions) during the study phase.
The levodopa group showed superior recall accuracy for new words over five learning sessions compared with the placebo group and better recognition accuracy at a 1-month follow-up for words learnt with a semantic description.
These findings suggest that dopamine boosts initial lexical acquisition and enhances longer-term consolidation of words learnt with semantic information, consistent with dopaminergic enhancement of semantic salience.
虽然多巴胺在调节执行功能、工作记忆和联想学习方面的作用已得到证实；但其在单词学习及更广泛的语言处理中的作用尚不清楚。这项初步研究使用明确学习范式，调查了健康年轻成年人中突触多巴胺水平升高对新单词学习能力的影响。
采用双盲、安慰剂对照、组间设计。参与者在1周内完成5次学习课程，每次课程服用左旋多巴或安慰剂（五剂，100毫克）。每次课程包括一个学习阶段，随后是一个测试阶段。测试阶段包括对学习阶段之前与不熟悉物体（一半带有语义描述）配对的新（非单词）名称进行回忆和识别测试。
与安慰剂组相比，左旋多巴组在五次学习课程中对新单词的回忆准确率更高，并且在1个月随访时，对带有语义描述的所学单词的识别准确率更高。
这些发现表明，多巴胺促进初始词汇习得，并增强所学单词与语义信息的长期巩固，这与多巴胺能增强语义显著性一致。
