Neural oscillations in the theta range (4–8 Hz) are thought to underlie associative memory function in the hippocampal-cortical network. While there is ample evidence supporting a role of theta oscillations in animal and human memory, most evidence is correlational. Non-invasive brain stimulation (NIBS) can be employed to modulate cortical oscillatory activity to influence brain activity, and possibly modulate deeper brain regions, such as hippocampus, through strong and reliable cortico-hippocampal functional connections. We applied focal transcranial alternating current stimulation (tACS) at 6 Hz over left parietal cortex to modulate brain activity in the putative cortico-hippocampal network to influence associative memory encoding. After encoding and brain stimulation, participants completed an associative memory and a perceptual recognition task. Results showed that theta tACS significantly decreased associative memory performance but did not affect perceptual memory performance. These results show that parietal theta tACS modulates associative processing separately from perceptual processing, and further substantiate the hypothesis that theta oscillations are implicated in the cortico-hippocampal network and associative encoding.

θ 范围 (4-8 Hz) 的神经振荡被认为是海马-皮层网络中联想记忆功能的基础。虽然有充分的证据支持 theta 振荡在动物和人类记忆中的作用，但大多数证据是相关的。非侵入性脑刺激 (NIBS) 可用于调节皮质振荡活动以影响大脑活动，并可能通过强大而可靠的皮质-海马功能连接来调节更深层次的大脑区域，例如海马体。我们在左顶叶皮层应用 6 Hz 的局灶经颅交流电刺激 (tACS) 来调节假定的皮质-海马网络中的大脑活动，以影响联想记忆编码。在编码和大脑刺激之后，参与者完成了联想记忆和感知识别任务。结果表明，theta tACS 显着降低了联想记忆表现，但不影响知觉记忆表现。这些结果表明，顶叶 theta tACS 调节关联处理与感知处理分开，并进一步证实了θ振荡与皮质-海马网络和关联编码有关的假设。