Ennaceur A, Michalikova S, Chazot P L
University of Sunderland, Sunderland Pharmacy School, Wharncliffe Street, Sunderland, SR1 3SD, UK.
Behav Brain Res. 2009 Feb 11;197(2):417-34. doi: 10.1016/j.bbr.2008.10.007. Epub 2008 Oct 15.
Three set of experiments were performed in an enclosed space (open-field) and in an open space (elevated platform). The surface of the open-field and the elevated platform were divided in nine equal squares. Rats were exposed (without previous habituation) in a unique session (experiment 1) or three consecutive sessions (experiment 2) either to an open-field (enclosed space) or to an elevated platform (open space) with and without an object on the centre of the field. In experiment 3, rats were exposed (without previous habituation) either to an enclosed or an open space on five consecutive sessions, one session a day. They were tested in an object recognition test in sessions 1, 3 and 5. In sessions 2 and 4, no objects were present. In experiment 1, we recorded the latency, frequency and duration of entries into different areas of the field. In experiment 3, we recorded the latency, frequency and duration of contacts with objects in addition to entries into different areas of the field. The first experiment demonstrates that rats exposed for the first time to an enclosed or an open space do not express neophobia toward novel objects in the absence of walls that surround an open-field. They crossed frequently into and spent more time in areas occupied with an object than in unoccupied areas. After two sessions of habituation to an empty open space or an empty enclosed space, the latency of first approach to a novel object is reduced while the frequency and duration of approaches are increased. The third experiment on object recognition confirmed that rats do not avoid novel objects; they made frequent visit and spent more time in the corner of the field occupied with an object than in empty corners. Recording of crossings provided detailed information about the patterns of exploratory behavior of rats but failed to reveal discrimination between novel and familiar objects which was evident in both open and enclosed space with recording of contacts with objects on the fifth exposure.
在封闭空间（旷场）和开放空间（高架平台）进行了三组实验。旷场和高架平台的表面被划分为九个相等的正方形区域。大鼠在单次实验（实验1）或连续三次实验（实验2）中（无前习惯化处理）暴露于旷场（封闭空间）或高架平台（开放空间），场中央放置或不放置物体。在实验3中，大鼠在连续五天的实验中（无前习惯化处理），每天一次，分别暴露于封闭或开放空间。在第1、3和5次实验中对它们进行物体识别测试。在第2和4次实验中，不放置物体。在实验1中，我们记录了大鼠进入场地不同区域的潜伏期、频率和持续时间。在实验3中，除了记录大鼠进入场地不同区域的情况外，还记录了它们与物体接触的潜伏期、频率和持续时间。第一个实验表明，首次暴露于封闭或开放空间的大鼠，在没有围绕旷场的墙壁的情况下，对新物体不表现出新物恐惧症。它们频繁穿过并在有物体的区域比在无物体的区域停留更长时间。在对空的开放空间或空的封闭空间进行两次习惯化实验后，首次接近新物体的潜伏期缩短，而接近的频率和持续时间增加。第三个关于物体识别的实验证实，大鼠不回避新物体；它们频繁到访并在场地中有物体的角落比在空角落停留更长时间。对穿越情况的记录提供了大鼠探索行为模式的详细信息，但未能揭示在第五次接触物体时，无论是在开放还是封闭空间中，大鼠对新物体和熟悉物体之间存在明显的辨别能力。
