Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience-MHeNS, European Graduate School of Neuroscience-EURON, Maastricht University, Maastricht, The Netherlands.
Behav Brain Res. 2012 Jul 1;232(2):335-47. doi: 10.1016/j.bbr.2012.03.022. Epub 2012 Apr 3.
The object recognition task (ORT) is a popular one-trial learning test for animals. In the current study, we investigated several methodological issues concerning the task. Data was pooled from 28 ORT studies, containing 731 male Wistar rats. We investigated the relationship between 3 common absolute- and relative discrimination measures, as well as their relation to exploratory activity. In this context, the effects of pre-experimental habituation, object familiarity, trial duration, retention interval and the amnesic drugs MK-801 and scopolamine were investigated. Our analyses showed that the ORT is very sensitive, capable of detecting subtle differences in memory (discrimination) and exploratory performance. As a consequence, it is susceptible to potential biases due to (injection) stress and side effects of drugs. Our data indicated that a minimum amount of exploration is required in the sample and test trial for stable significant discrimination performance. However, there was no relationship between the level of exploration in the sample trial and discrimination performance. In addition, the level of exploration in the test trial was positively related to the absolute discrimination measure, whereas this was not the case for relative discrimination measures, which correct for exploratory differences, making them more resistant to exploration biases. Animals appeared to remember object information over multiple test sessions. Therefore, when animals have encountered both objects in prior test sessions, the object preference observed in the test trial of 1h retention intervals is probably due to a relative difference in familiarity between the objects in the test trial, rather than true novelty per se. Taken together, our findings suggest to take into consideration pre-experimental exposure (familiarization) to objects, habituation to treatment procedures, and the use of relative discrimination measures when using the ORT.
物体识别任务（ORT）是一种流行的动物单次学习测试。在当前的研究中，我们研究了该任务的几个方法学问题。数据来自 28 项 ORT 研究，共包含 731 只雄性 Wistar 大鼠。我们研究了 3 种常见的绝对和相对辨别测量之间的关系，以及它们与探索性活动的关系。在这种情况下，我们研究了预实验习惯化、物体熟悉度、试验持续时间、记忆间隔以及致遗忘药物 MK-801 和东莨菪碱的作用。我们的分析表明，ORT 非常敏感，能够检测到记忆（辨别）和探索性能的细微差异。因此，它容易受到（注射）压力和药物副作用等潜在偏差的影响。我们的数据表明，在样本和测试试验中，需要进行最低限度的探索，以获得稳定的显著辨别性能。然而，样本试验中的探索水平与辨别性能之间没有关系。此外，测试试验中的探索水平与绝对辨别测量呈正相关，而对于相对辨别测量则不是这样，因为相对辨别测量可以纠正探索差异，使其更能抵抗探索偏差。动物似乎可以在多个测试会议中记住物体信息。因此，当动物在前几个测试会议中遇到两个物体时，在 1 小时记忆间隔的测试试验中观察到的物体偏好可能是由于测试试验中物体之间的相对熟悉度差异造成的，而不是真正的新颖性本身。总之，我们的研究结果表明，在使用 ORT 时，需要考虑实验前的物体暴露（熟悉度）、对治疗程序的习惯化以及使用相对辨别测量。
