Persistent neuronal spiking has long been considered the mechanism underlying working memory, but recent proposals argue for alternative ‘activity-silent’ substrates. Using monkey and human electrophysiology data, we show here that attractor dynamics that control neural spiking during mnemonic periods interact with activity-silent mechanisms in the prefrontal cortex (PFC). This interaction allows memory reactivations, which enhance serial biases in spatial working memory. Stimulus information was not decodable between trials, but remained present in activity-silent traces inferred from spiking synchrony in the PFC. Just before the new stimulus, this latent trace was reignited into activity that recapitulated the previous stimulus representation. Importantly, the reactivation strength correlated with the strength of serial biases in both monkeys and humans, as predicted by a computational model that integrates activity-based and activity-silent mechanisms. Finally, single-pulse transcranial magnetic stimulation applied to the human PFC between successive trials enhanced serial biases, thus demonstrating the causal role of prefrontal reactivations in determining working-memory behavior.

长期以来，持久性神经元突增一直被认为是工作记忆的基础机制，但最近的提议主张使用替代的“活性沉默”底物。使用猴子和人类的电生理数据，我们在这里显示了在记忆期间控制神经突刺的吸引子动力学与前额叶皮层（PFC）中的活动沉默机制相互作用。这种交互作用可以重新激活内存，从而增强空间工作内存中的串行偏差。两次试验之间的刺激信息无法解码，但仍存在于通过PFC的同步性脉冲推导而得出的无活动痕迹中。就在新刺激方案出现之前，这种潜在的痕迹被重新点燃，重新概括了先前刺激方案的表现。重要的，正如整合了基于活动和沉默的机制的计算模型所预测的，重新激活强度与猴子和人类的系列偏倚强度相关。最后，在连续试验之间对人PFC施加单脉冲经颅磁刺激可增强系列偏倚，从而证明前额叶活化在确定工作记忆行为中的因果作用。