Yagi Shunya, Drewczynski Dimka, Wainwright Steven R, Barha Cindy K, Hershorn Olivia, Galea Liisa A M
Graduate Program in Neuroscience, University of British Columbia, Vancouver, Canada.
Department of Psychology, University of British Columbia, Vancouver, Canada.
Horm Behav. 2017 Jan;87:69-79. doi: 10.1016/j.yhbeh.2016.10.019. Epub 2016 Oct 29.
The hippocampus and dorsal striatum are important structures involved in place and response learning strategies respectively. Both sex and estrous cycle phase differences in learning strategy preference exist following cue competition paradigms. Furthermore, significant effects of sex and learning strategy on hippocampal neural plasticity have been reported. However, associations between learning strategy and immediate early gene (IEG) expression in the hippocampus and dorsal striatum are not completely understood. In the current study we investigated the effects of sex and estrous cycle phase on strategy choice and IEG expression in the hippocampus and dorsal striatum of rats following cue competition training in the Morris water maze. We found that proestrous rats were more likely to choose a place strategy than non-proestrous or male rats. Although male cue strategy users travelled greater distances than the other groups on the first day of training, there were no other sex or strategy differences in the ability to reach a hidden or a visible platform. Female place strategy users exhibited greater zif268 expression and male place strategy users exhibited greater cFos expression compared to all other groups in CA3. Furthermore, cue strategy users had greater expression of cFos in the dorsal striatum than place strategy users. Shorter distances to reach a visible platform were associated with less activation of cFos in CA3 and CA1 of male place strategy users. Our findings indicate multiple differences in brain activation with sex and strategy use, despite limited behavioral differences between the sexes on this cue competition paradigm.
海马体和背侧纹状体分别是参与位置学习策略和反应学习策略的重要结构。在线索竞争范式后，学习策略偏好存在性别和发情周期阶段差异。此外，已有报道称性别和学习策略对海马体神经可塑性有显著影响。然而，学习策略与海马体和背侧纹状体中即早基因（IEG）表达之间的关联尚未完全明确。在本研究中，我们调查了在莫里斯水迷宫中进行线索竞争训练后，性别和发情周期阶段对大鼠海马体和背侧纹状体中策略选择和IEG表达的影响。我们发现，处于发情前期的大鼠比非发情前期大鼠或雄性大鼠更倾向于选择位置策略。尽管在训练的第一天，使用线索策略的雄性大鼠比其他组移动的距离更远，但在找到隐藏或可见平台的能力方面，没有其他性别或策略差异。与CA3中的所有其他组相比，使用位置策略的雌性大鼠zif268表达更高，而使用位置策略的雄性大鼠cFos表达更高。此外，与使用位置策略的大鼠相比，使用线索策略的大鼠背侧纹状体中cFos的表达更高。对于使用位置策略的雄性大鼠，到达可见平台的距离越短，CA3和CA1中cFos的激活越少。我们的研究结果表明，尽管在这种线索竞争范式中两性之间的行为差异有限，但在大脑激活方面存在多种性别和策略使用差异。
