Waldhauser Gerd T, Braun Verena, Hanslmayr Simon
Department of Psychology, University of Konstanz, 78457 Konstanz, Germany, Department of Neuropsychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, 44801 Bochum, Germany, and
Department of Psychology, University of Konstanz, 78457 Konstanz, Germany, School of Psychology, University of Birmingham, Edgbaston, B15 2TT, Birmingham, United Kingdom.
J Neurosci. 2016 Jan 6;36(1):251-60. doi: 10.1523/JNEUROSCI.2101-15.2016.
Episodic memory retrieval is assumed to rely on the rapid reactivation of sensory information that was present during encoding, a process termed "ecphory." We investigated the functional relevance of this scarcely understood process in two experiments in human participants. We presented stimuli to the left or right of fixation at encoding, followed by an episodic memory test with centrally presented retrieval cues. This allowed us to track the reactivation of lateralized sensory memory traces during retrieval. Successful episodic retrieval led to a very early (∼100-200 ms) reactivation of lateralized alpha/beta (10-25 Hz) electroencephalographic (EEG) power decreases in the visual cortex contralateral to the visual field at encoding. Applying rhythmic transcranial magnetic stimulation to interfere with early retrieval processing in the visual cortex led to decreased episodic memory performance specifically for items encoded in the visual field contralateral to the site of stimulation. These results demonstrate, for the first time, that episodic memory functionally relies on very rapid reactivation of sensory information.
Remembering personal experiences requires a "mental time travel" to revisit sensory information perceived in the past. This process is typically described as a controlled, relatively slow process. However, by using electroencephalography to measure neural activity with a high time resolution, we show that such episodic retrieval entails a very rapid reactivation of sensory brain areas. Using transcranial magnetic stimulation to alter brain function during retrieval revealed that this early sensory reactivation is causally relevant for conscious remembering. These results give first neural evidence for a functional, preconscious component of episodic remembering. This provides new insight into the nature of human memory and may help in the understanding of psychiatric conditions that involve the automatic intrusion of unwanted memories.
情景记忆检索被认为依赖于对编码过程中出现的感觉信息的快速重新激活，这一过程被称为“情景再现”。我们在两项针对人类参与者的实验中研究了这个鲜为人知的过程的功能相关性。我们在编码时将刺激呈现于注视点的左侧或右侧，随后进行情景记忆测试，测试中中央呈现检索线索。这使我们能够在检索过程中追踪侧化感觉记忆痕迹的重新激活。成功的情景检索导致在编码时视野对侧的视觉皮层中，侧化的α/β（10 - 25赫兹）脑电图（EEG）功率在很早的时候（约100 - 200毫秒）就出现重新激活并降低。应用节律性经颅磁刺激来干扰视觉皮层的早期检索处理，导致情景记忆表现下降，特别是对于在刺激部位对侧视野中编码的项目。这些结果首次证明，情景记忆在功能上依赖于感觉信息的非常快速的重新激活。
回忆个人经历需要“心理时光旅行”来重温过去感知到的感觉信息。这个过程通常被描述为一个可控的、相对缓慢的过程。然而，通过使用脑电图以高时间分辨率测量神经活动，我们表明这种情景检索需要感觉脑区非常快速的重新激活。在检索过程中使用经颅磁刺激来改变脑功能表明，这种早期感觉重新激活与有意识的记忆有因果关系。这些结果首次为情景记忆的功能性、前意识成分提供了神经学证据。这为人类记忆的本质提供了新的见解，并可能有助于理解涉及不需要的记忆自动侵入的精神疾病。
