Our memory for time is a fundamental ability that we use to judge the duration of events, put our experiences into a temporal context, and decide when to initiate actions. The medial entorhinal cortex (MEC), with its direct projections to the hippocampus, has been proposed to be the key source of temporal information for hippocampal time cells. However, the behavioral relevance of such temporal firing patterns remains unclear, as most of the paradigms used for the study of temporal processing and time cells are either spatial tasks or tasks for which MEC function is not required. In this study, we asked whether the MEC is necessary for rats to perform a time duration discrimination task (TDD), in which rats were trained to discriminate between 10-s and 20-s delay intervals. After reaching a 90% performance criterion, the rats were assigned to receive an excitotoxic MEC-lesion or sham-lesion surgery. We found that after recovering from surgery, rats with MEC lesions were impaired on the TDD task in comparison to rats with sham lesions, failing to return to criterion performance. Their impairment, however, was specific to the longer, 20-s delay trials. These results indicate that time processing is dependent on MEC neural computations only for delays that exceed 10 s, perhaps because long-term memory resources are needed to keep track of longer time intervals.

我们对时间的记忆是一种基本能力，我们用它来判断事件的持续时间，将我们的经验置于时间背景中，并决定何时开始行动。内侧内嗅皮层 (MEC) 直接投射到海马，被认为是海马时间细胞时间信息的关键来源。然而，这种时间触发模式的行为相关性仍不清楚，因为用于研究时间处理和时间单元的大多数范式要么是空间任务，要么是不需要 MEC 功能的任务。在这项研究中，我们询问大鼠执行持续时间辨别任务 (TDD) 是否需要 MEC，其中训练大鼠辨别 10 秒和 20 秒的延迟间隔。在达到 90% 的性能标准后，大鼠被分配接受兴奋毒性 MEC 损伤或假损伤手术。我们发现，从手术中恢复后，与假损伤的大鼠相比，MEC 损伤的大鼠在 TDD 任务中受损，未能恢复到标准表现。然而，他们的损害是特定于更长的 20 秒延迟试验。这些结果表明，时间处理仅对超过 10 秒的延迟依赖于 MEC 神经计算，这可能是因为需要长期记忆资源来跟踪更长的时间间隔。