Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada.
Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada.
Behav Brain Res. 2025 Feb 4;477:115303. doi: 10.1016/j.bbr.2024.115303. Epub 2024 Oct 22.
Male and female rodents display unique search strategies when exploring new and familiar environments. Sex differences are well-documented in the literature and may be observed in tasks that rely on spontaneous exploration (e.g., recognition memory tests). Therefore, we assessed patterns of male and female rat behavior in the object-in-place (OiP) test, a common recognition memory paradigm involving object-location associations. Twelve male and 12 female adult Long Evans rats were tested four times in the 1-h OiP test and exploratory behaviors were compared during habituation, sample, and test phases. Results revealed that females moved faster and farther than males, showed increased immobility frequency and reduced immobility duration, reduced outer zone mobility duration, and increased inner zone entrances, compared to males during habituations. During sample phases, female rats moved faster than males, displayed reduced immobility frequency in the inner zone, and demonstrated consistent distance travelled across repeated sessions; conversely, male rats moved less in later sessions and exhibited increased mobility frequency in the outer zone. Analyses comparing test phase behavior revealed females continued to move faster than males; however, no other sex differences were observed. These findings are consistent with previous literature highlighting unique sex differences in explorative behaviors during recognition testing. Sex differences in locomotion and mobility state behaviors may be more indicative of individual motivation and search strategy between the sexes and less indicative of recognition memory.
雄性和雌性啮齿动物在探索新环境和熟悉环境时表现出独特的搜索策略。文献中充分记录了性别差异，并且在依赖于自发探索的任务中可以观察到这些差异（例如，识别记忆测试）。因此，我们评估了雄性和雌性大鼠在物体位置（OiP）测试中的行为模式，这是一种涉及物体位置关联的常见识别记忆范式。12 只雄性和 12 只雌性成年长耳大仓鼠在 1 小时的 OiP 测试中接受了四次测试，并比较了在适应期、样本期和测试期的探索行为。结果表明，与雄性相比，雌性在适应期移动速度更快、距离更远，表现出更高的静止频率和更短的静止持续时间，减少了外区活动持续时间，增加了内区进入次数。在样本期，雌性大鼠移动速度比雄性快，内区静止频率降低，并且在重复的测试中表现出一致的移动距离；相反，雄性大鼠在后面的测试中移动较少，在外区表现出更高的活动频率。比较测试期行为的分析表明，雌性大鼠继续比雄性大鼠移动得更快；然而，没有观察到其他性别差异。这些发现与以前的文献一致，强调了在识别测试中探索行为的独特性别差异。运动和移动状态行为的性别差异可能更能说明性别之间的个体动机和搜索策略，而不是识别记忆。
