Amplitude Transfer Entropy of Local Field Potential Signals in Ventral Hippocampus and Medial Prefrontal Cortex of Normal Mice for Novel Object Recognition Memory
School of Biomedical Engineering and Technology, Tianjin Medical University, Tianjin 300070, China
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Received
Published
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2025-09-16
2026-07-28
2026-01-12
Online Date
2026-08-14
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摘要
新物体识别(novel object recognition,NOR)实验通过比较小鼠对新奇物体和熟悉物体的探索时间差异,评估其识别记忆能力。研究了正常小鼠在NOR行为学实验中腹侧海马(ventral hippocampus,vHPC)和内侧前额叶皮层(medial prefrontal cortex,mPFC)之间局部场电位信号(local field potential,LFPs)的幅值传递熵,旨在探索两脑区在NOR任务中的信息传递机制。实验获取了6只正常小鼠在探索新奇物体和熟悉物体时vHPC和mPFC的多通道LFPs信号,分别计算了各脑区的功率谱密度和脑区间的幅值传递熵。结果显示,正常小鼠对新奇物体的探索时间显著长于对熟悉物体的探索时间。在新奇物体探索阶段,vHPC和mPFC的theta振荡的功率谱密度均显著高于熟悉物体探索阶段。同时,该阶段中从vHPC到mPFC的幅值传递熵也显著增大。以上结果表明,vHPC和mPFC的theta振荡在小鼠对新奇物体的识别中起关键作用,且vHPC向mPFC增强的信息传递可能是识别记忆形成的潜在机制。
Abstract
The recognition memory ability is assessed by the novel object recognition (NOR) test, which compares the exploration time difference between novel and familiar objects in mice. The amplitude transfer entropy (ATE) of local field potential (LFP) signals between the ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC) was investigated in normal mice during this test, aiming to explore the information transmission mechanism between these two brain regions underlying the NOR task. Multichannel LFP signals were acquired from the vHPC and mPFC in six normal mice during exploration of novel and familiar objects, and the power spectral density (PSD) for each individual brain region and the amplitude transfer entropy (ATE) between the regions were calculated respectively. It was observed that the exploration time for novel objects is significantly longer than that for familiar objects in normal mice. During the stage of exploring novel objects, the power spectral density of theta oscillations in both the vHPC and mPFC is found to be significantly greater than that during the stage of exploring familiar objects. Furthermore, the amplitude transfer entropy from the vHPC to the mPFC is also shown to be significantly increased during this stage. These results indicate that theta oscillations in the vHPC and mPFC play a critical role in novel object recognition in mice, and the enhanced directional information transfer from vHPC to mPFC may represent a potential mechanism for the formation of recognition memory.
ZHANG Jin-ying, YANG Hui-yun, LIU Tiao-tiao, BAI Wen-wen, ZHENG Xu-yuan.
Amplitude Transfer Entropy of Local Field Potential Signals in Ventral Hippocampus and Medial Prefrontal Cortex of Normal Mice for Novel Object Recognition Memory[J].
Science Technology and Engineering, 2026, 26(21): 9047-9053 DOI:10.12404/j.issn.1671-1815.2506658
局部场电位(local field potential, LFP)是记录电极尖端附近局部区域的神经元兴奋性和抑制性突触后电位的总和[19],能特异性地反映电极尖端附近局部神经微环路的电活动,具有较高的空间分辨率,可达100~500 μm。LFP通过植入式电极的方式直接记录细胞外场电位,对头皮肌电、眼电及动物运动时电缆引起的运动伪迹不敏感,因此可以有效避免颅骨对信号的衰减和大部分肌电干扰,同时其良好的空间特异性使得能够在自由活动的小鼠中稳定记录特定脑区的神经振荡活动。现代微驱动电极阵列技术进一步支持多通道同步记录,结合运动轨迹跟踪系统,可实现神经信号与行为事件的精准时间对齐。此外,由于vHPC位于大脑深部,LFP可直接靶向记录深部脑区,提供其神经活动的第一手数据,这是研究vHPC-mPFC环路在NOR中信息传递机制的前提。
传递熵(transfer entropy, TE)是一种用于衡量两个随机过程之间定向信息传递的非参数统计量[20],能够有效捕捉信号或变量之间的因果关系和信息流动方向。幅值传递熵(amplitude transfer entropy,ATE)是在传统传递熵基础上发展出的一种改进算法。该方法以信号的瞬时幅值序列作为输入变量,实现对时间序列之间幅值信息传递的定量评估。由于神经振荡本质上是非线性过程,而传递熵能够捕捉非线性的定向信息传递,因此幅值传递熵可以通过计算幅值时间序列间的信息传递,量化此类非线性神经相互作用[21]。此外,幅值传递熵不仅提供明确的方向性指标,还显著降低了传统功能连接方法中常见的容积传导伪迹的影响。由于LFP记录技术已有效规避了颅骨衰减带来的信号失真,结合幅值传递熵的定向分析能够更精确地解析脑区之间信息传递的时序特性。
采用幅值传递熵定量表征正常小鼠在NOR实验过程中vHPC与mPFC之间的信息传递。幅值传递熵是一个非负的标量指标,用于量化从一个脑区的神经振荡幅值时间序列到另一个脑区的定向的、非线性信息传递强度。但幅值传递熵的值以绝对信息量(如比特)为单位,没有与“完全”连通性相关联的值,因而缺乏一个用于研究比较的归一化基准。故采用了Lobier等[22]的方法,使用定向幅值传递熵(directed amplitude transfer entropy, dATE)计算ATE的差分形式,即计算从脑区X到Y与从Y到X的ATE的差值。dATE是一个可正可负的标量值,它通过计算两个相反方向信息传递(ATEX→Y和ATEY→X)的差值,来表征信息传递的净优势方向及其相对强度。具体计算过程如下。
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