University of Virginia, Charlottesville.
J Cogn Neurosci. 2023 Sep 1;35(9):1463-1477. doi: 10.1162/jocn_a_02022.
Memory encoding and memory retrieval are neurally distinct brain states that can be differentiated on the basis of cortical network activity. However, it is unclear whether sustained engagement of one network or fluctuations between multiple networks give rise to these memory states. The spatiotemporal dynamics of memory states may have important implications for memory behavior and cognition; however, measuring temporally resolved signals of cortical networks poses a challenge. Here, we recorded scalp electroencephalography from participants performing a mnemonic state task in which they were biased toward memory encoding or retrieval. We performed a microstate analysis to measure the temporal dynamics of cortical networks throughout this mnemonic state task. We find that Microstate E, a putative analog of the default mode network, shows temporally sustained dissociations between memory encoding and retrieval, with greater engagement during retrieve compared with encode trials. We further show that decreased engagement of Microstate E is a general property of encoding, rather than a reflection of retrieval suppression. Thus, memory success, as well as cognition more broadly, may be influenced by the ability to engage or disengage Microstate E in a goal-dependent manner.
记忆编码和记忆检索是神经上不同的大脑状态，可以根据皮质网络活动来区分。然而，尚不清楚是一个网络的持续参与还是多个网络之间的波动导致了这些记忆状态。记忆状态的时空动力学可能对记忆行为和认知有重要影响；然而，测量皮质网络的时间分辨信号具有挑战性。在这里，我们记录了参与者在执行记忆状态任务时的头皮脑电图，在该任务中，他们偏向于记忆编码或检索。我们进行了微状态分析，以测量整个记忆状态任务中皮质网络的时间动态。我们发现微状态 E，默认模式网络的一个假定类似物，在记忆编码和检索之间表现出时间上的持续分离，在检索试验中比在编码试验中有更大的参与度。我们进一步表明，微状态 E 的参与度降低是编码的一般特性，而不是检索抑制的反映。因此，记忆成功以及更广泛的认知，可能受到以目标依赖的方式参与或不参与微状态 E 的能力的影响。
