Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong, China.
MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge CB2 7EF, United Kingdom.
J Neurosci. 2024 Sep 11;44(37):e0189242024. doi: 10.1523/JNEUROSCI.0189-24.2024.
The act of recalling memories can paradoxically lead to the forgetting of other associated memories, a phenomenon known as retrieval-induced forgetting (RIF). Inhibitory control mechanisms, primarily mediated by the prefrontal cortex, are thought to contribute to RIF. In this study, we examined whether stimulating the medial prefrontal cortex (mPFC) with transcranial direct current stimulation modulates RIF and investigated the associated electrophysiological correlates. In a randomized study, 50 participants (27 males and 23 females) received either real or sham stimulation before performing retrieval practice on target memories. After retrieval practice, a final memory test to assess RIF was administered. We found that stimulation selectively increased the retrieval accuracy of competing memories, thereby decreasing RIF, while the retrieval accuracy of target memories remained unchanged. The reduction in RIF was associated with a more pronounced beta desynchronization within the left dorsolateral prefrontal cortex (left-DLPFC), in an early time window (<500 ms) after cue onset during retrieval practice. This led to a stronger beta desynchronization within the parietal cortex in a later time window, an established marker for successful memory retrieval. Together, our results establish the causal involvement of the mPFC in actively suppressing competing memories and demonstrate that while forgetting arises as a consequence of retrieving specific memories, these two processes are functionally independent. Our findings suggest that stimulation potentially disrupted inhibitory control processes, as evidenced by reduced RIF and stronger beta desynchronization in fronto-parietal brain regions during memory retrieval, although further research is needed to elucidate the specific mechanisms underlying this effect.
回忆行为会导致其他相关记忆的遗忘，这种现象被称为提取诱发遗忘（retrieval-induced forgetting，RIF）。抑制控制机制，主要由前额叶皮层介导，被认为有助于 RIF。在这项研究中，我们研究了经颅直流电刺激（transcranial direct current stimulation，tDCS）刺激内侧前额叶皮层（medial prefrontal cortex，mPFC）是否调节 RIF，并探讨了相关的电生理相关性。在一项随机研究中，50 名参与者（27 名男性和 23 名女性）在对目标记忆进行检索练习之前接受了真实或假刺激。在检索练习后，进行了最终的记忆测试来评估 RIF。我们发现刺激选择性地提高了竞争记忆的检索准确性，从而降低了 RIF，而目标记忆的检索准确性保持不变。RIF 的减少与在检索练习期间 cue 出现后的早期时间窗口（<500ms）内左背外侧前额叶皮层（left dorsolateral prefrontal cortex，left-DLPFC）内更明显的β去同步化有关。这导致在稍后的时间窗口内，顶叶皮层内的β去同步化更强，这是成功记忆检索的标志。总之，我们的结果确立了 mPFC 在主动抑制竞争记忆中的因果关系，并表明虽然遗忘是由于检索特定记忆而产生的，但这两个过程在功能上是独立的。我们的发现表明，刺激可能破坏了抑制控制过程，证据是在记忆检索期间，额顶叶脑区的 RIF 降低和β去同步化增强，尽管需要进一步的研究来阐明这种效应的具体机制。
