Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.
Nat Neurosci. 2012 Jun 17;15(7):1032-9. doi: 10.1038/nn.3138.
The encoding and storage of experience by the hippocampus is essential for the formation of episodic memories and the transformation of individual experiences into semantic structures such as maps and schemas. The rodent hippocampus compresses ongoing experience into repeating theta sequences, but the factors determining the content of theta sequences are not understood. Here we first show that the spatial paths represented by theta sequences in rats extend farther in front of the rat during acceleration and higher running speeds and begin farther behind the rat during deceleration. Second, the length of the path is directly related to the length of the theta cycle and the number of gamma cycles in it. Finally, theta sequences represent the environment in segments or 'chunks'. These results imply that information encoded in theta sequences is subject to powerful modulation by behavior and task variables. Furthermore, these findings suggest a potential mechanism for the cognitive 'chunking' of experience.
海马体对经验的编码和存储对于形成情景记忆以及将个体经验转化为地图和图式等语义结构至关重要。啮齿动物的海马体将正在进行的经验压缩成重复的θ序列，但决定θ序列内容的因素尚不清楚。在这里，我们首先表明，在加速和更高的跑步速度期间，大鼠的θ序列所代表的空间路径在大鼠前方延伸得更远，而在减速期间，大鼠的θ序列所代表的空间路径开始在大鼠后方延伸。其次，路径的长度与θ周期的长度以及其中的γ周期的数量直接相关。最后，θ序列以片段或“块”的形式表示环境。这些结果表明，θ序列中编码的信息受到行为和任务变量的强大调制。此外，这些发现为经验的认知“分块”提供了一种潜在的机制。
