Learning and consolidation of salient information: The causal role of theta oscillations

我们的记忆是选择性的。尽管我们尽了最大努力，但我们只能记住我们所经历的事件的一小部分。动机突显是决定记忆编码和持续的重要因素。两个不同的研究表明，动机突显与theta频段(4-8赫兹)的额叶神经振荡以及连接多巴胺能区与前额叶区域和海马体的多巴胺能回路的活动密切相关。然而，到目前为止，额叶theta和支持学习的多巴胺能回路之间的关系在人类中仍然很大程度上是未知的。这个项目将测试关键问题(I)theta振荡是否在学习中起到因果作用，以及(Ii)额叶theta状态如何影响支持学习的神经机制。为了解决这些问题，我们将使用无创经颅交流电刺激(Tacs)在学习动机显著和中性信息的过程中直接引入theta振荡，并通过脑电(EEG)和功能磁共振成像(FMRI)测量其对行为的影响和涉及的神经机制。实验一(Tacs-EEG的联合研究)将询问学习过程中的theta夹带如何改善对动机显著和中性信息的记忆。实验2(Tacs-fMRI联合研究)将询问theta振荡的增强将如何增强(I)通过皮质-中脑边缘多巴胺能回路学习和(Ii)通过增加信息的神经重放来保持记忆。重要的是，这个项目不仅有可能促进我们对theta振荡在学习和记忆巩固中的因果作用的了解，而且还可能为应用环境带来重要的好处(例如，如何在教育中改善学习或在临床环境中恢复记忆)。此外，该项目将通过学习TAC和高级多变量模式分析功能磁共振数据，极大地扩展我在认知神经科学领域的专业知识，从而使申请者拥有各种复杂的工具，成为一名独立的记忆研究人员。

Our memories are selective. Despite our best efforts, we can only remember a fraction of the events that we experience. Motivational salience is an important factor that determines the encoding and persistence of memories. Two disparate lines of research have shown that motivational salience is strongly associated with frontal neural oscillations in the theta band (4-8 Hz) and by activity in the dopaminergic circuit linking dopaminergic regions with prefrontal regions and the hippocampus. To date, however, the relationship between frontal theta and the dopaminergic circuit in support of learning remains largely unknown in humans. This project will test the crucial questions (i) whether theta oscillations have a causal role in learning and (ii) how frontal theta states influence the neural mechanisms that support learning. To address these questions, we will use non-invasive transcranial Alternate Current Stimulation (tACS) to directly entrain theta oscillations during learning of motivationally salient and neutral information and measure its effects on behavior and the neural mechanisms involved by using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Experiment 1 (a combined tACS-EEG study) will ask how theta entrainment during learning benefits memory for motivationally salient and neutral information. Experiment 2 (a combined tACS-fMRI study) will ask how the boosting of theta oscillations will enhance (i) learning via the cortico-mesolimbic dopaminergic circuit and (ii) memory retention via increased neural replay of information. Importantly, this project not only has the potential to advance our knowledge about the causal role of theta oscillations in learning and memory consolidation, but could also lead to important benefits for applied settings (e.g. how to improve learning in education or to rehabilitate memory in clinical settings). Moreover, this project will greatly extend my expertise in the field of cognitive neuroscience by learning tACS and advanced multivariate pattern analyses for fMRI data, thereby equipping the applicant with a variety of complex tools to be an independent memory researcher.