Department of Psychology, Stanford University, Stanford, CA 94305, USA.
Proc Natl Acad Sci U S A. 2011 Apr 5;108(14):5903-8. doi: 10.1073/pnas.1016939108. Epub 2011 Mar 21.
Remembering an event from the past is often complicated by the fact that our memories are cluttered with similar events. Though competition is a fundamental part of remembering, there is little evidence of how mnemonic competition is neurally represented. Here, we assessed whether competition between visual memories is captured in the relative degree to which target vs. competing memories are reactivated within the ventral occipitotemporal cortex (VOTC). To assess reactivation, we used multivoxel pattern analysis of fMRI data, quantifying the degree to which retrieval events elicited patterns of neural activity that matched those elicited during encoding. Consistent with recent evidence, we found that retrieval of visual memories was associated with robust VOTC reactivation and that the degree of reactivation scaled with behavioral expressions of target memory retrieval. Critically, competitive remembering was associated with more ambiguous patterns of VOTC reactivation, putatively reflecting simultaneous reactivation of target and competing memories. Indeed, the more weakly that target memories were reactivated, the more likely that competing memories were later remembered. Moreover, when VOTC reactivation indicated that conflict between target and competing memories was high, frontoparietal mechanisms were markedly engaged, revealing specific neural mechanisms that tracked competing mnemonic evidence. Together, these findings provide unique evidence that neural reactivation captures competition between individual memories, providing insight into how well target memories are retrieved in the present and how likely competing memories will be remembered in the future.
记住过去的事件往往会因为我们的记忆中充斥着类似的事件而变得复杂。尽管竞争是记忆的一个基本部分，但关于记忆竞争是如何在神经上表现的证据很少。在这里，我们评估了视觉记忆之间的竞争是否可以通过目标与竞争记忆在腹侧枕颞皮质（VOTC）内被重新激活的相对程度来捕捉。为了评估重新激活，我们使用 fMRI 数据的多体素模式分析，量化了检索事件引发的神经活动模式与编码期间引发的模式的匹配程度。与最近的证据一致，我们发现视觉记忆的检索与 VOTC 的强烈再激活有关，并且再激活的程度与目标记忆检索的行为表现成正比。至关重要的是，竞争性记忆与 VOTC 再激活更模糊的模式相关，推测反映了目标和竞争记忆的同时再激活。事实上，目标记忆被重新激活得越弱，竞争记忆后来被记住的可能性就越大。此外，当 VOTC 再激活表明目标和竞争记忆之间的冲突很高时，额顶叶机制明显参与，揭示了跟踪竞争记忆证据的特定神经机制。总之，这些发现提供了独特的证据，证明神经再激活可以捕捉个体记忆之间的竞争，为了解当前目标记忆的提取程度以及未来竞争记忆的记忆可能性提供了线索。
