Behavioral Neurology Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
Department of Neurology, The University of Chicago, Chicago, IL 60611, USA.
Cereb Cortex. 2022 Oct 20;32(21):4715-4732. doi: 10.1093/cercor/bhab512.
Classical lesion studies led to a consensus that episodic and procedural memory arises from segregated networks identified with the hippocampus and the caudate nucleus, respectively. Neuroimaging studies, however, show that competitive and cooperative interactions occur between networks during memory tasks. Furthermore, causal experiments to manipulate connectivity between these networks have not been performed in humans. Although nodes common to both networks, such as the precuneus and ventrolateral thalamus, may mediate their interaction, there is no experimental evidence for this. We tested how network-targeted noninvasive brain stimulation affects episodic-procedural network interactions and how these network manipulations affect episodic and procedural memory in healthy young adults. Compared to control (vertex) stimulation, hippocampal network-targeted stimulation increased within-network functional connectivity and hippocampal connectivity with the caudate. It also increased episodic, relative to procedural, memory, and this persisted one week later. The differential effect on episodic versus procedural memory was associated with increased functional connectivity between the caudate, precuneus, and ventrolateral thalamus. These findings provide direct evidence of episodic-procedural network competition, mediated by regions common to both networks. Enhanced hippocampal network connectivity may boost episodic, but decrease procedural, memory by co-opting resources shared between networks.
经典的病变研究得出共识，即情景和程序记忆分别来自海马体和尾状核的分离网络。然而，神经影像学研究表明，在记忆任务中，网络之间存在竞争和合作相互作用。此外，尚未在人类中进行操纵这些网络之间连通性的因果实验。虽然两个网络共有的节点，如楔前叶和腹外侧丘脑，可能介导它们的相互作用，但目前还没有实验证据支持这一点。我们测试了针对网络的非侵入性脑刺激如何影响情景-程序网络相互作用，以及这些网络操作如何影响健康年轻成年人的情景和程序记忆。与对照（顶点）刺激相比，海马体网络靶向刺激增加了网络内的功能连接和海马体与尾状核的连接。它还增加了情景记忆，相对于程序记忆，这种情况持续了一周。情景记忆与程序记忆的差异效应与尾状核、楔前叶和腹外侧丘脑之间的功能连接增加有关。这些发现提供了情景-程序网络竞争的直接证据，由两个网络共有的区域介导。增强的海马体网络连通性可能通过利用网络之间共享的资源来增强情景记忆，但会降低程序记忆。
