Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
Department of Psychiatry, University of Minnesota, Minneapolis, MN 55455, USA.
J Neurosci Methods. 2022 Dec 1;382:109725. doi: 10.1016/j.jneumeth.2022.109725. Epub 2022 Oct 13.
Defensive and threat-related behaviors are common models for aspects of human mental illness.These behaviors are typically quantified by potentially laborious and/or computationally intensive video recording and post hoc analysis. Depending on the analysis method, the resulting measurements can be noisy or inaccurate. Other defensive behaviors, such as suppression of operant reward seeking, require extensive animal pre-training. Inertial tracking and accelerometry can be computationally efficient, but require specialized hardware.
We quantified rodent defensive behavior using a commercially available electrophysiology headstage with 3-axis accelerometry integration during a threat conditioning and extinction paradigm. We tested multiple pre-processing and smoothing methods and correlated them against video-derived freezing and suppression of operant bar pressing.
The best approach to tracking defensive behavior from accelerometry was Gaussian filter smoothing of the first derivative. Behavior scores from this method reproduced canonical conditioning and extinction curves. Timepoint-to-timepoint correlations between accelerometry,video, and bar press metrics were statistically significant but modest (largest r = 0.53, between accelerometry and bar press). These increased when traditional thresholding-based analyses were used, at the cost of a loss of temporal resolution (r = 0.97 between thresholded accelerometry and percent time freezing).
Accelerometry's integration with standard electrophysiology systems and relatively light weight signal processing may make it particularly well suited to detect behavior in resource-constrainedor real-time applications.
Accelerometry allows researchers already using electrophysiology to assess defensive behaviors without the need for additional behavioral measures or video. The modest correlations between metrics suggest that each measures a distinct aspect of defensive behavior. Accelerometry is a viable alternative to current defensive measurements, and its non-overlap with other metrics may allow for more sophisticated dissection of threat responses.
防御和威胁相关行为是人类精神疾病的常见模型。这些行为通常通过潜在费力和/或计算密集型的视频记录和事后分析来量化。根据分析方法的不同，得出的测量结果可能存在噪声或不准确。其他防御行为，如操作性奖励寻求的抑制，需要广泛的动物预训练。惯性跟踪和加速度计可以计算效率高，但需要专门的硬件。
我们使用市售的带有 3 轴加速度计集成的电生理头架在威胁条件作用和消退范式期间量化了啮齿动物的防御行为。我们测试了多种预处理和平滑方法，并将它们与视频衍生的冻结和操作性棒按压抑制进行了相关分析。
从加速度计跟踪防御行为的最佳方法是对一阶导数进行高斯滤波平滑。该方法的行为评分再现了经典的条件作用和消退曲线。加速度计、视频和棒按压指标之间的逐点相关性具有统计学意义但适中（最大 r = 0.53，加速度计和棒按压之间）。当使用传统的基于阈值的分析时，这些相关性增加了，但代价是丧失了时间分辨率（阈值加速度计和百分比时间冻结之间 r = 0.97）。
加速度计与标准电生理系统的集成以及相对较轻的信号处理可能使其特别适合在资源受限或实时应用中检测行为。
加速度计允许已经使用电生理学的研究人员在无需额外行为测量或视频的情况下评估防御行为。指标之间的适度相关性表明，每个指标都测量了防御行为的一个独特方面。加速度计是当前防御测量的可行替代品，其与其他指标的不重叠可能允许对威胁反应进行更复杂的剖析。
