Department of Psychology, University of Konstanz, Postfach ZPR, 78457 Konstanz, Germany; Zukunftskolleg, University of Konstanz, Fach 216, 78457 Konstanz, Germany.
Neuroimage. 2014 Jan 15;85 Pt 2:648-55. doi: 10.1016/j.neuroimage.2013.05.121. Epub 2013 Jun 11.
Brain oscillations are increasingly recognized by memory researchers as a useful tool to unravel the neural mechanisms underlying the formation of a memory trace. However, the increasing numbers of published studies paint a rather complex picture of the relation between brain oscillations and memory formation. Concerning oscillatory amplitude, for instance, increases as well as decreases in various frequency bands (theta, alpha, beta and gamma) were associated with memory formation. These results cast doubt on frameworks putting forward the idea of an oscillatory signature that is uniquely related to memory formation. In an attempt to clarify this issue we here provide an alternative perspective, derived from classic cognitive frameworks/principles of memory. On the basis of Craik's levels of processing framework and Tulving's encoding specificity principle we hypothesize that brain oscillations during encoding might primarily reflect the perceptual and cognitive processes engaged by the encoding task. These processes may then lead to later successful retrieval depending on their overlap with the processes engaged by the memory test. As a consequence, brain oscillatory correlates of memory formation could vary dramatically depending on how the memory is encoded, and on how it is being tested later. Focusing on oscillatory amplitude changes and on theta-to-gamma cross-frequency coupling, we here review recent evidence showing how brain oscillatory subsequent memory effects can be modulated, and sometimes even be reversed, by varying encoding tasks, and the contextual overlap between encoding and retrieval.
脑振荡越来越被记忆研究人员视为一种有用的工具，可以揭示记忆痕迹形成背后的神经机制。然而，越来越多发表的研究对脑振荡与记忆形成之间的关系描绘了一幅相当复杂的图景。例如，在不同的频段（theta、alpha、beta 和 gamma）中，振荡幅度的增加和减少都与记忆形成有关。这些结果使那些提出与记忆形成唯一相关的振荡特征的框架产生了怀疑。为了解决这个问题，我们在这里提供了一个替代的视角，该视角源自经典的认知框架/记忆原则。基于 Craik 的加工层次框架和 Tulving 的编码特异性原则，我们假设编码期间的脑振荡可能主要反映了编码任务所涉及的感知和认知过程。这些过程可能会根据它们与记忆测试中所涉及的过程的重叠程度，从而导致以后成功的检索。因此，记忆形成的脑振荡相关性可能会根据记忆的编码方式以及以后的测试方式而有很大的不同。我们重点关注振荡幅度的变化和 theta 到 gamma 的跨频耦合，这里回顾了最近的证据，表明如何通过改变编码任务以及编码和检索之间的上下文重叠，来调节甚至有时反转脑振荡的后续记忆效应。
