Li Shuangyan, Ouyang Mei, Liu Tiaotiao, Bai Wenwen, Yi Hu, Tian Xin
Laboratory of Neurobiology in Medicine, School of Biomedical Engineering, Tianjin Medical University, Tianjin 300070, China.
Laboratory of Neurobiology in Medicine, School of Biomedical Engineering, Tianjin Medical University, Tianjin 300070, China.
Behav Brain Res. 2014 Mar 15;261:297-304. doi: 10.1016/j.bbr.2013.12.030. Epub 2013 Dec 31.
Working memory (WM) refers to the short-term maintenance of information with higher cognitive functions. Recent researches show that local field potentials (LFPs) and spikes, as different modes of neural signals, encode WM, respectively. There is a growing interest in how these two signals encode WM in coordination. The aim of this study is to investigate spike-LFP coupling coding of WM via the joint entropy analysis. The experimental data were multi-channel spikes and LFPs obtained from SD rat prefrontal cortex through the implanted microelectrode array during the WM tasks in Y-maze. The short-time Fourier transform (STFT) was applied to analyze the power changes of WM related frequency bands in the LFPs. The joint entropy indexes (JEIs) between spikes and the principle components of LFPs were calculated for each pair of the spike and the LFP series during WM. The results showed that the power of theta (4-12 Hz), low gamma (LG, 30-60 Hz) and high gamma band (HG, 60-100 Hz) in LFPs increased during the WM tasks. In addition, the JEIs between spikes and LFPs components (theta, LG and HG) significantly increased in the correct trials. Besides, the coupling levels were low when the rats waiting in the starting area. These results suggest that the JEIs between spikes and LFPs components (theta, LG and HG) encode WM effectively. These findings could lead to improved understanding of the WM mechanism from the view of spike-LFP joint encoding.
工作记忆（WM）是指对信息进行短期维持并具有更高认知功能。近期研究表明，局部场电位（LFP）和锋电位作为不同的神经信号模式，分别对工作记忆进行编码。人们越来越关注这两种信号如何协同编码工作记忆。本研究的目的是通过联合熵分析来探究工作记忆的锋电位-LFP耦合编码。实验数据是在Y迷宫工作记忆任务期间，通过植入的微电极阵列从SD大鼠前额叶皮层获得的多通道锋电位和LFP。应用短时傅里叶变换（STFT）分析LFP中与工作记忆相关频段的功率变化。在工作记忆期间，针对每一对锋电位和LFP序列，计算锋电位与LFP主成分之间的联合熵指数（JEI）。结果表明，在工作记忆任务期间，LFP中θ波（4 - 12Hz）、低γ波（LG，30 - 60Hz）和高γ波频段（HG，60 - 100Hz）的功率增加。此外，在正确试验中，锋电位与LFP成分（θ波、LG和HG）之间的JEI显著增加。此外，当大鼠在起始区域等待时，耦合水平较低。这些结果表明，锋电位与LFP成分（θ波、LG和HG）之间的JEI有效地编码了工作记忆。这些发现可能会从锋电位-LFP联合编码的角度增进对工作记忆机制的理解。
