Gaskin Stephane, Tardif Marilyn, Cole Emily, Piterkin Pavel, Kayello Lima, Mumby Dave G
Center for Studies in Behavioral Neurobiology, Concordia University, Montréal, Québec, Canada.
Behav Processes. 2010 Jan;83(1):61-71. doi: 10.1016/j.beproc.2009.10.003. Epub 2009 Oct 27.
We investigated whether object familiarization was related to novel-object preference in the novel-object preference (NOP) test in rats. In Experiment 1, we found that no significant correlation existed between the time spent investigating 2 identical copies of a sample object and the degree of preference for a novel object. In Experiment 2, rats investigated 2 identical sample objects for a total of 5, 30, 60, 90 or 120s. Investigatory preference for the novel object was compared to chance expectancy as well as between the groups. Only the 90-s group and the 120-s group displayed above-chance investigatory preference for the novel object, but novel-object preference for these 2 groups did not differ from each other, suggesting that a minimal amount of sample object investigation is necessary for rats to develop a novel-object preference, beyond which no increase in novel-object preference was found. In Experiments 3 and 4, normal rats and rats with hippocampal lesions were given repeated test trials, with the same sample object presented with a different novel object, at 24-h and (Experiment 3) and 35-s intervals (Experiment 4). In both experiments, novel-object preference did not increase in magnitude with repeated sample object exposures, suggesting that increased familiarity with the sample object does not result in increased novel-object preference. Rats with lesions of the dorsal hippocampus showed an unreliable investigatory preference for the novel object. These results are discussed in terms of the potential limitations of the NOP test as a tool for the assessment of object-recognition memory in rats.
我们研究了在大鼠的新物体偏好（NOP）测试中，物体熟悉度是否与新物体偏好相关。在实验1中，我们发现，对一个样本物体的两个相同复制品进行探究所花费的时间与对新物体的偏好程度之间不存在显著相关性。在实验2中，大鼠对两个相同的样本物体进行总共5秒、30秒、60秒、90秒或120秒的探究。将对新物体的探究偏好与随机预期以及各实验组之间进行比较。只有90秒组和120秒组对新物体表现出高于随机水平的探究偏好，但这两组对新物体的偏好没有差异，这表明大鼠形成新物体偏好需要对样本物体进行最少时间的探究，超过这个时间，新物体偏好不会增加。在实验3和实验4中，正常大鼠和海马体损伤的大鼠接受重复测试，在24小时间隔（实验3）和35秒间隔（实验4）呈现相同的样本物体和不同的新物体。在这两个实验中，随着对样本物体的重复暴露，新物体偏好的程度没有增加，这表明对样本物体熟悉度的增加不会导致新物体偏好的增加。背侧海马体损伤的大鼠对新物体表现出不可靠的探究偏好。我们根据NOP测试作为评估大鼠物体识别记忆工具的潜在局限性对这些结果进行了讨论。
