Evaluation of Hemisphere Lateralization with Bilateral Local Field Potential Recording in Secondary Motor Cortex of Mice

Yunan Chen; Ming Li; Ying Zheng; Li Yang

doi:10.3791/59310

JoVE Journal
Neuroscience

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JoVE Journal Neuroscience

Evaluation of Hemisphere Lateralization with Bilateral Local Field Potential Recording in Secondary Motor Cortex of Mice

小鼠二次运动皮质中双边局部场电位记录半球横向化评价

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07:03 min

July 31, 2019

DOI: 10.3791/59310-v

Yunan Chen^1,2, Ming Li³, Ying Zheng³, Li Yang¹

¹School of Life Sciences,Guangzhou University, ²Institute for Brain Research and Rehabilitation,South China Normal University, ³School of Life Sciences,South China Normal University

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Overview

This study presents in vivo electrophysiological recordings of local field potentials (LFP) in the bilateral secondary motor cortex (M2) of mice, focusing on hemisphere lateralization. The research investigates synchronization differences between APP/PS1 mice and wild-type (WT) controls, revealing altered brain lateralization potentially linked to Alzheimer's disease.

Key Study Components

Area of Science

Neuroscience
Electrophysiology
Alzheimer's Disease Research

Background

Local field potentials (LFPs) are vital for assessing neuronal activity.
Synchronization is important for understanding hemisphere lateralization.
Alzheimer's disease may alter brain lateralization mechanisms.
The study uses a mouse model (APP/PS1) to explore these changes.

Purpose of Study

To evaluate synchronization levels between left and right M2 in APP/PS1 mice.
To investigate the impact of Alzheimer’s pathology on hemisphere lateralization.
To identify potential biomarkers for Alzheimer's treatments through electrophysiological metrics.

Methods Used

In vivo electrophysiological recording of LFPs in the mouse M2 regions.
APP/PS1 mice and wild-type controls were used to assess lateralization effects.
Coherence and cross-correlation analyses were performed on the captured LFP data.
Electrode placement, quality control, and data acquisition were detailed in the protocol.
Methods included high-pass and low-pass filtering and amplification of signals for analysis.

Main Results

Cross-correlation showed that wild-type mice exhibited significant asymmetry in LFPs, unlike APP/PS1 mice, which had increased synchronization.
The findings indicated higher gamma coherence in APP/PS1 mice, suggesting reduced lateralization.
Electrophysiological alterations may connect to the underlying mechanisms of Alzheimer's disease pathology.

Conclusions

The study demonstrates that altered synchronization in M2 could serve as a marker for Alzheimer's pathology.
Insights may contribute to understanding neuronal mechanisms related to hemisphere lateralization and Alzheimer's disease.
This research highlights the importance of electrophysiological measurements in exploring disease models.

Frequently Asked Questions

What advantages does this technique offer?

This technique allows for direct measurement of neuronal activity and synchronization in live animal models, providing crucial insights into brain function and disease.

How is the biological model implemented?

The study uses APP/PS1 transgenic mice to understand the effects of Alzheimer’s disease on brain lateralization and synchrony in M2 regions.

What outcomes are obtained from this protocol?

The protocol yields electrophysiological data that reflect neuronal synchronization, coherence, and potential lateralization changes in the brain.

How can this method be adapted for other studies?

The methods can be applied to different brain regions or diseases, allowing researchers to explore various aspects of neuronal connectivity and activity.

What are the key considerations when conducting these experiments?

It’s crucial to monitor anesthesia depth carefully and to ensure that all surgical and recording procedures are conducted with precision to obtain reliable data.

What limitations should be recognized?

Limitations include the invasiveness of the procedure and potential variability in responses among different mice, which may affect data interpretation.

在小鼠的双边二次运动皮层(M2)中,我们提供局部场势(LFP)的体内电生理记录,可用于评估半球侧化。研究表明,与WT对照组相比,APP/PS1小鼠左右M2的同步水平发生了变化。

该技术可用于审查区域间电生理学的一些基本特性，用于半球横向化，以及连通性、方向性和耦合性。电生理测量是一种敏感而有效的评价动物、神经元活动的方法。该协议为支持电信号同步提供了更好的方法。

对阿尔茨海默病发病机制中可能改变的大脑横向化的潜在机制的理解，可能为阿尔茨海默病治疗的潜在生物标志物提供新的见解。手术前，通过用钳子进行尾部或手趾捏，确认小鼠麻醉的深度。接下来，将鼠标放在立体仪器中，并固定其头部。

在两只眼睛上涂抹软膏，以保持眼睛湿润。然后，剃光头，对该区域进行消毒。在剃光区域中间进行 12 到 15 毫米的小切口。

使用钳子，轻轻地将头皮从中线拉开。之后，轻轻地分离皮肤，取出残留组织。清洁头骨，使用过氧化氢涂层棉芽。

在立体显微镜下，在头骨的左右两侧钻两个小孔，一到一点一点五毫米的半径，允许将录制的微电杆插入M2区域。小心地用钨针取出杜拉母体。然后，使用机械微操纵器，在孔中插入两个单独的记录微电子，填充0.5摩尔氯化钠，角度为60度。

对于 LFP 记录，缓慢地将左右玻璃电极降到 M2 坐标。为了质量控制，使用差分放大器测试每个电极的电阻。接下来，将录制过程设置为 0.1 赫兹高通和 1000 赫兹低通，放大 1000 倍。

在麻醉下，以稳定状态收集数字化的原始 LFP 数据至少 60 秒，鼠标以两次呼吸以均匀的速度呼吸。记录后，慢慢将电极从大脑中升起。使用分析软件保存数据并脱机分析。

要执行交叉相关分析，在分析软件中，单击分析，然后波形关联，并导入数据。接下来，将一个波形通道信号分配给第一个信道，另一个作为参考。将宽度设置为 2，偏移设置为 1。

随后，通过选择开始时间和结束时间，将两个 LP 的持续时间设置为 100 秒。然后，按过程按钮执行交叉相关分析。单击文件，导出为，然后以文本格式保存与生成的弹出式图表对应的交叉关联结果。

之后，删除时间滞后时的相关性值，范围从零加减 01 秒，然后处理其他交叉相关数据。要执行一致性分析，请运行分析软件中的数据。接下来，将两个 LFP 信号排列为第一个和第二个波形通道，然后将块大小值设置为 4096。

块大小表示在第一个用于实际转换的数据点数。块大小越大，频率分辨率越好。手动移动虚线，以确保两个通道中信号的时间精度设置为同一时间段。

按添加区域按钮加载区域并执行相干分析。之后单击文件并保存为，以文本格式保存与生成的弹出式图表对应的一致性结果。为了了解早期阿尔茨海默氏病病理学是否损害半球横向化的能力，APP/PS1小鼠的左右M2和野生类型对等小鼠记录了细胞外LFP，并分析了它们的交叉相关性。

在野生型小鼠中，结果表明，正时差时左右LFP之间的平均相关性与负时差的均值相关性显著，这意味着野生类型对控的M2区域存在半球不对称。相比之下，APP/PS1小鼠的左右LFP在时域中表现出较高的同步性，表明左右M2之间的不对称度降低。然后从LFP中过滤伽马振荡，并进行相干分析，以测量伽马频率范围内电信号的类似性。结果表明，APP/PS1小鼠左右M2的伽马相干性明显高于野生小鼠，表明同步性较高，因此在 APP/PS1 小鼠中左、右M2之间的横向化降低。

聚氨酯有毒和致癌，所以请始终小心，并遵循安全规定时处理它。每小时测试麻醉深度非常重要，以确保记录的LFP稳定。记录和分析过程可以应用于其他大脑通路，特别是对于没有自由移动动物多通道记录系统的实验室。

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