Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France.
Laboratoire de Neurosciences Cognitives, Aix-Marseille Univ/CNRS, Marseille, France.
Psychopharmacology (Berl). 2018 Apr;235(4):1307-1316. doi: 10.1007/s00213-018-4846-3. Epub 2018 Feb 9.
The role of dopaminergic system in decision-making is well documented, and evidence suggests that it could play a significant role in response selection processes. The N-40 is a fronto-central event-related potential, generated by the supplementary motor areas (SMAs) and a physiological index of response selection processes. The aim of the present study was to determine whether infraclinical effects of dopamine depletion on response selection processes could be evidenced via alterations of the N-40. We obtained a dopamine depletion in healthy volunteers with the acute phenylalanine and tyrosine depletion (APTD) method which consists in decreasing the availability of dopamine precursors. Subjects realized a Simon task in the APTD condition and in the control condition. When the stimulus was presented on the same side as the required response, the stimulus-response association was congruent and when the stimulus was presented on the opposite side of the required response, the stimulus-response association was incongruent. The N-40 was smaller for congruent associations than for incongruent associations. Moreover, the N-40 was sensitive to the level of dopaminergic activity with a decrease in APTD condition compared to control condition. This modulation of the N-40 by dopaminergic level could not be explained by a global decrease of cerebral electrogenesis, since negativities and positivities indexing the recruitment of the primary motor cortex (anatomically adjacent to the SMA) were unaffected by APTD. The specific sensitivity of N-40 to ATPD supports the model of Keeler et al. (Neuroscience 282:156-175, 2014) according to which the dopaminergic system is involved in response selection.
多巴胺系统在决策中的作用已有充分的文献记载，有证据表明它可能在反应选择过程中发挥重要作用。N-40 是一种额中央事件相关电位，由补充运动区（SMA）产生，是反应选择过程的生理指标。本研究旨在确定多巴胺耗竭对反应选择过程的亚临床影响是否可以通过 N-40 的改变来证明。我们使用急性苯丙氨酸和酪氨酸耗竭（APTD）方法在健康志愿者中引起多巴胺耗竭，该方法包括减少多巴胺前体的可用性。受试者在 APTD 条件和对照条件下完成 Simon 任务。当刺激与所需反应在同一侧出现时，刺激-反应关联是一致的，而当刺激出现在所需反应的相反侧时，刺激-反应关联是不一致的。与不一致的关联相比，一致的关联的 N-40 更小。此外，N-40 对多巴胺能活动水平敏感，与对照条件相比，APTD 条件下的 N-40 减少。这种由多巴胺水平调节的 N-40 不能用大脑电生成的整体下降来解释，因为负性和正性反应指数（与 SMA 解剖相邻的初级运动皮层的募集）不受 APTD 的影响。N-40 对 ATPD 的特异性敏感性支持 Keeler 等人的模型（神经科学 282:156-175, 2014），根据该模型，多巴胺系统参与反应选择。
