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

记忆是有选择性的。尽管我们尽了最大的努力，我们只能记住我们经历的事件的一小部分。动机突显性是决定记忆编码和记忆持久性的重要因素。两条不同的研究路线表明，动机显著性与θ波（4-8 Hz）的额叶神经振荡以及连接多巴胺能区域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θ和多巴胺能回路之间的关系在人类学习的支持仍然是未知的。该项目将测试以下关键问题：（i）θ振荡是否在学习中起因果作用，以及（ii）额叶θ状态如何影响支持学习的神经机制。为了解决这些问题，我们将使用非侵入性经颅交流刺激（tACS）直接夹带θ振荡在学习的动机显着和中性的信息，并测量其对行为的影响，并通过使用脑电图（EEG）和功能磁共振成像（fMRI）的神经机制。实验1（结合tACS-EEG研究）将询问学习过程中θ夹带如何有益于动机显著和中性信息的记忆。实验2（tACS-fMRI联合研究）将探讨θ振荡的增强如何增强（i）通过皮质-中脑边缘多巴胺能回路的学习和（ii）通过增加神经对信息的重放来增强记忆保持。重要的是，这个项目不仅有可能推进我们对θ振荡在学习和记忆巩固中的因果作用的认识，而且还可能为应用环境带来重要的好处（例如如何改善教育中的学习或在临床环境中恢复记忆）。此外，这个项目将大大扩展我在认知神经科学领域的专业知识，通过学习tACS和先进的多变量模式分析功能磁共振成像数据，从而装备申请人与各种复杂的工具，是一个独立的记忆研究者。

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.