BACKGROUND Increased motor activity is a defining characteristic of patients with ADHD, and spontaneously hypertensive rats have been suggested to be an animal model of this disorder. In the present study, we wanted to use linear and non-linear methods to explore differences in motor activity patterns in SHR/NCrl rats compared to Wistar Kyoto (WKY/NHsd) rats. METHODS A total number of 42 rats (23 SHR/NCrl and 19 WKY/NHsd, male and female) were tested. At PND 51, the animals' movements were video-recorded during an operant test procedure that lasted 90 min. Total activity level and velocity (mean and maximum), standard deviation (SD) and root mean square successive differences (RMSSD) were calculated. In addition, we used Fourier analysis, autocorrelations and two measures of complexity to characterize the time series; sample entropy and symbolic dynamics. RESULTS The SHR/NCrl rats showed increased total activity levels in addition to increased mean and maximum velocity of movements. The variability measures, SD and RMSSD, were markedly lower in the SHR/NCrl compared to the WKY/NHsd rats. At the same time, the SHR/NCrl rats displayed a higher complexity of the time series, particularly with regard to the total activity level as evidenced by analyses of sample entropy and symbolic dynamics. Autocorrelation analyses also showed differences between the two strains. In the Fourier analysis, the SHR/NCrl rats had an increased variance in the high frequency part of the spectrum, corresponding to the time period of 9-17 s. CONCLUSION The findings show that in addition to increased total activity and velocity of movement, the organization of behavior is different in SHR/NCrl relative to WKY/NHsd controls. Compared to controls, behavioral variability is reduced in SHR/NCrl at an aggregate level, and, concomitantly, more complex and unpredictable from moment-to-moment. These finding emphasize the importance of the measures and methods used when characterizing behavioral variability. If valid for ADHD, the results indicate that decreased behavioral variability can co-exist with increased behavioral complexity, thus representing a challenge to current theories of variability in ADHD.

中文翻译：

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与Wistar Kyoto大鼠相比，自发性高血压大鼠的运动活动模式。

背景运动活动的增加是ADHD患者的定义特征，并且自发性高血压大鼠被认为是该疾病的动物模型。在本研究中，我们希望使用线性和非线性方法来探索SHR / NCrl大鼠与Wistar Kyoto（WKY / NHsd）大鼠相比在运动活动模式上的差异。方法测试了42只大鼠（23只SHR / NCrl和19只WKY / NHsd，雄性和雌性）。在PND 51上，在持续90分钟的操作测试过程中对动物的运动进行了录像。计算总活动水平和速度（平均值和最大值），标准差（SD）和均方根连续差（RMSSD）。另外，我们使用傅立叶分析，自相关和两个复杂性度量来表征时间序列。样本熵和符号动力学。结果SHR / NCrl大鼠除平均运动速度和最大运动速度外，还显示出总活动水平的增加。与WKY / NHsd大鼠相比，SHR / NCrl大鼠的变异性测量值SD和RMSSD明显较低。同时，SHR / NCrl大鼠表现出较高的时间序列复杂性，特别是在总活动水平方面，如样本熵和符号动力学分析所证明的。自相关分析还显示了两种菌株之间的差异。在傅立叶分析中，SHR / NCrl大鼠在频谱的高频部分具有增加的方差，对应于9-17 s的时间段。结论研究结果表明，除了增加总活动量和运动速度之外，相对于WKY / NHsd控件，SHR / NCrl中的行为组织有所不同。与对照组相比，SHR / NCrl的行为变异性总体上降低了，因此，从瞬间到瞬间，更加复杂且不可预测。这些发现强调了在表征行为变异性时所使用的措施和方法的重要性。如果对多动症有效，结果表明行为变异性的降低可以与行为复杂性的增加并存，从而代表了对当前多动症变异性理论的挑战。这些发现强调了在表征行为变异性时所使用的措施和方法的重要性。如果对多动症有效，结果表明行为变异性的降低可以与行为复杂性的增加并存，从而代表了对当前多动症变异性理论的挑战。这些发现强调了在表征行为变异性时所使用的措施和方法的重要性。如果对多动症有效，结果表明行为变异性的降低可以与行为复杂性的增加并存，从而代表了对当前多动症变异性理论的挑战。