University of Connecticut, Department of Psychology, Behavioral Neuroscience, 406 Babbidge Rd., Unit 1020, Storrs, CT 06269, USA.
Physiol Behav. 2012 Feb 1;105(3):645-52. doi: 10.1016/j.physbeh.2011.09.027. Epub 2011 Oct 8.
The hippocampus has been linked to spatial navigation and the striatum to response learning. The current study focuses on how these brain regions continue to interact when an animal is very familiar with the task and the environment and must continuously switch between navigation strategies. Rats were trained to solve a plus maze using a place or a response strategy on different trials within a testing session. A room cue (illumination) was used to indicate which strategy should be used on a given trial. After extensive training, animals underwent dorsal hippocampus, dorsal lateral striatum or sham lesions. As expected hippocampal lesions predominantly caused impairment on place but not response trials. Striatal lesions increased errors on both place and response trials. Competition between systems was assessed by determining error type. Pre-lesion and sham animals primarily made errors to arms associated with the wrong (alternative) strategy, this was not found after lesions. The data suggest a qualitative change in the relationship between hippocampal and striatal systems as a task is well learned. During acquisition the two systems work in parallel, competing with each other. After task acquisition, the two systems become more integrated and interdependent. The fact that with extensive training (as something becomes a "habit"), behaviors become dependent upon the dorsal lateral striatum has been previously shown. The current findings indicate that dorsal lateral striatum involvement occurs even when the behavior is spatial and continues to require hippocampal processing.
海马体与空间导航有关，纹状体与反应学习有关。本研究侧重于当动物非常熟悉任务和环境并且必须在不同的导航策略之间不断切换时，这些大脑区域如何继续相互作用。在测试过程中，大鼠被训练使用位置策略或反应策略在不同的试验中解决加号迷宫。房间提示（照明）用于指示给定试验中应使用哪种策略。经过广泛的训练，动物接受了背侧海马体、背侧外侧纹状体或假手术损伤。正如预期的那样，海马体损伤主要导致位置试验而不是反应试验的障碍。纹状体损伤增加了位置和反应试验的错误。通过确定错误类型来评估系统之间的竞争。在损伤之前和假手术动物主要犯与错误（替代）策略相关的臂的错误，这在损伤后没有发现。数据表明，随着任务的熟练掌握，海马体和纹状体系统之间的关系发生了质的变化。在获得过程中，两个系统并行工作，相互竞争。在任务获得后，两个系统变得更加集成和相互依赖。以前已经表明，经过广泛的训练（因为某些行为成为“习惯”），行为变得依赖于背外侧纹状体。当前的发现表明，即使行为是空间的并且仍然需要海马体处理，背外侧纹状体也会参与其中。
