Experiences of animal and human beings are structured by the continuity of space and time coupled with the uni-directionality of time. In addition to its pivotal position in spatial processing and navigation, the hippocampal system also plays a central, multiform role in several types of temporal processing. These include timing and sequence learning, at scales ranging from meso-scales of seconds to macro-scales of minutes, hours, days and beyond, encompassing the classical functions of short term memory, working memory, long term memory, and episodic memories (comprised of information about when, what, and where). This review article highlights the principal findings and behavioral contexts of experiments in rats showing: 1) timing: tracking time during delays by hippocampal ‘time cells’ and during free behavior by hippocampal-afferent lateral entorhinal cortex ramping cells; 2) ‘online’ sequence processing: activity coding sequences of events during active behavior; 3) ‘off-line’ sequence replay: during quiescence or sleep, orderly reactivation of neuronal assemblies coding awake sequences. Studies in humans show neurophysiological correlates of episodic memory comparable to awake replay. Neural mechanisms are discussed, including ion channel properties, plateau and ramping potentials, oscillations of excitation and inhibition of population activity, bursts of high amplitude discharges (sharp wave ripples), as well as short and long term synaptic modifications among and within cell assemblies. Specifically conceived neural network models will suggest processes supporting the emergence of scalar properties (Weber’s law), and include different classes of feedforward and recurrent network models, with intrinsic hippocampal coding for ‘transitions’ (sequencing of events or places).

动物和人类的经验是由空间和时间的连续性以及时间的单向性构成的。除了在空间处理和导航中的关键地位外，海马系统还在几种类型的时间处理中发挥着中心、多种形式的作用。这些包括时间和序列学习，范围从秒的中尺度到分钟、小时、天甚至更长时间的宏观尺度，包括短期记忆、工作记忆、长期记忆和情景记忆的经典功能（包括关于时间、内容和地点的信息）。这篇评论文章强调了大鼠实验的主要发现和行为背景，显示：1）时间：海马“时间细胞”延迟期间和海马传入外侧内嗅皮层斜坡细胞自由行为期间的跟踪时间；2）“在线”序列处理：活动行为期间事件的活动编码序列；3）“离线”序列回放：在静止或睡眠期间，编码清醒序列的神经元组件有序地重新激活。对人类的研究表明，情景记忆的神经生理学相关性与清醒回放相当。讨论了神经机制，包括离子通道特性、平台和斜坡电位、激发的振荡和群体活动的抑制、高振幅放电的爆发（锐波波纹），以及细胞组件之间和内部的短期和长期突触修饰。