The J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA.
Cereb Cortex. 2010 Jul;20(7):1604-12. doi: 10.1093/cercor/bhp223. Epub 2009 Oct 27.
The medial temporal lobe (MTL) and the prefrontal cortex (PFC) are known to be critical structures for human memory processes. Furthermore, it has been suggested that they are part of a memory network. Although memory-modulated interaction between PFC and MTL has been observed at the hemodynamic level, it remains unclear what the neuronal process is that mediates the communication between these 2 areas. Experiments in rodents suggest that field oscillations in the theta band (4-8 Hz) facilitate PFC-MTL interaction. No such evidence has been reported in humans. To address this problem, cortical electrical activity from MTL, PFC, and lateral temporal lobe was recorded from implanted electrode grids in 3 epilepsy patients performing a verbal free recall task. The data were analyzed using a parametric spectral method to obtain estimates of power, coherence, and Granger causality. A task-modulated increase in coherence values between PFC and MTL was seen during free recall as opposed to a baseline condition. Concurrently, the number of coherent PFC-MTL site pairs was significantly increased during recall. Granger causality analysis further revealed that the increased coherence is a consequence of higher bidirectional information flow between the 2 regions, with a generally greater driving from MTL to PFC, namely, (MTL-->PFC) > (PFC-->MTL).
内侧颞叶（MTL）和前额叶皮层（PFC）被认为是人类记忆过程的关键结构。此外，有人认为它们是记忆网络的一部分。虽然已经在血液动力学水平上观察到 PFC 和 MTL 之间的记忆调节相互作用，但介导这两个区域之间通讯的神经元过程仍不清楚。在啮齿动物中的实验表明，θ频段（4-8 Hz）的场振荡促进了 PFC-MTL 之间的相互作用。在人类中尚未有报道。为了解决这个问题，对 3 名正在进行言语自由回忆任务的癫痫患者进行了研究，使用植入的电极网格记录了 MTL、PFC 和外侧颞叶的皮质电活动。使用参数谱方法对数据进行了分析，以获得功率、相干性和格兰杰因果关系的估计值。与基线条件相比，在自由回忆期间观察到 PFC 和 MTL 之间的相干值呈任务调制性增加。同时，在回忆期间，相干的 PFC-MTL 部位对的数量显著增加。格兰杰因果关系分析进一步表明，增加的相干性是两个区域之间双向信息流增加的结果，通常是从 MTL 到 PFC 的驱动更大，即（MTL->PFC）>（PFC->MTL）。
