Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada.
Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.
Learn Mem. 2020 Apr 15;27(5):201-208. doi: 10.1101/lm.051243.119. Print 2020 May.
Behavioral flexibility is important in a changing environment. Previous research suggests that systems consolidation, a long-term poststorage process that alters memory traces, may reduce behavioral flexibility. However, exactly how systems consolidation affects flexibility is unknown. Here, we tested how systems consolidation affects: (1) flexibility in response to value changes and (2) flexibility in response to changes in the optimal sequence of actions. Mice were trained to obtain food rewards in a Y-maze by switching nose pokes between three arms. During initial training, all arms were rewarded and mice simply had to switch arms in order to maximize rewards. Then, after either a 1 or 28 d delay, we either devalued one arm, or we reinforced a specific sequence of pokes. We found that after a 1 d delay mice adapted relatively easily to the changes. In contrast, mice given a 28 d delay struggled to adapt, especially for changes to the optimal sequence of actions. Immediate early gene imaging suggested that the 28 d mice were less reliant on their hippocampus and more reliant on their medial prefrontal cortex. These data suggest that systems consolidation reduces behavioral flexibility, particularly for changes to the optimal sequence of actions.
行为灵活性在不断变化的环境中很重要。先前的研究表明，系统巩固是一种长期的存储后过程，会改变记忆痕迹，可能会降低行为灵活性。然而，系统巩固如何影响灵活性尚不清楚。在这里，我们测试了系统巩固如何影响：（1）对价值变化的灵活性；（2）对最佳动作序列变化的灵活性。老鼠通过在三个臂之间切换鼻刺来训练在 Y 形迷宫中获取食物奖励。在初始训练中，所有的手臂都有奖励，老鼠只需切换手臂就可以最大限度地获得奖励。然后，在 1 天或 28 天的延迟后，我们要么降低一个臂的价值，要么强化特定的戳刺序列。我们发现，在 1 天的延迟后，老鼠相对容易适应这些变化。相比之下，给予 28 天延迟的老鼠很难适应，尤其是对于最佳动作序列的变化。早期基因成像表明，28 天的老鼠较少依赖海马体，更多地依赖内侧前额叶皮质。这些数据表明，系统巩固降低了行为灵活性，特别是对最佳动作序列的变化。
