Department of Clinical Neurophysiology, University Medical Center Goettingen, University of Goettingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.
Department of Clinical Neurophysiology, University Medical Center Goettingen, University of Goettingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.
Brain Stimul. 2018 May-Jun;11(3):509-517. doi: 10.1016/j.brs.2017.12.007. Epub 2017 Dec 25.
Phase-amplitude cross-frequency coupling (PAC) is characterized by the modulation of the power of a fast brain oscillation (e.g., gamma) by the phase of a slow rhythm (e.g., theta). PAC in different sub- and neocortical regions is known to underlie effective neural communication and correlates with successful long-term memory formation.
OBJECTIVE/HYPOTHESIS: The present work aims to extend earlier observational data, by probing the functional role of theta-gamma PAC in the left temporal cortex in humans during verbal long-term memory encoding.
In three double-blinded, placebo-controlled experiments (n = 72), we employed cross-frequency transcranial alternating current stimulation (tACS) to externally modulate ongoing PAC during a verbal-associative learning task. Three types of cross-frequency tACS protocols were used: bursts of high gamma tACS were coupled to the peak or trough of the theta tACS cycle, and a control condition where gamma tACS was continuously superimposed at theta tACS cycles.
Gamma bursts coupled to the trough of theta tACS induced robust behavioral impairment in memory performance (p < .01), whereas gamma burst coupled to the peak or continuously superimposed with theta tACS had no significant behavioral effects.
Our results demonstrate direct evidence regarding the importance of theta-gamma coupling in verbal long-term memory formation.
相位-振幅跨频耦合（PAC）的特征是快速脑振荡（例如，伽马）的功率由慢节律（例如，theta）的相位调制。不同的皮质下和新皮质区域的 PAC 被认为是有效的神经通讯的基础，并与成功的长期记忆形成相关。
目的/假设：本研究旨在通过探测在人类左颞叶皮质在言语长期记忆编码过程中 theta-gammaPAC 的功能作用，扩展早期的观察性数据。
在三个双盲、安慰剂对照的实验中（n=72），我们使用跨频经颅交流电刺激（tACS）在言语联想学习任务期间对外调制持续的 PAC。使用了三种类型的跨频 tACS 方案：高 gamma tACS 爆发被耦合到 theta tACS 周期的波峰或波谷，以及 gamma tACS 连续叠加在 theta tACS 周期上的对照条件。
伽马爆发与 theta tACS 的波谷耦合导致记忆表现的行为显著受损（p<0.01），而伽马爆发与 theta tACS 的波峰耦合或连续叠加则没有显著的行为效应。
我们的结果提供了关于 theta-gamma 耦合在言语长期记忆形成中的重要性的直接证据。
