Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health; Neuroscience Research Center, Berlin, Germany.
German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany.
Elife. 2023 Apr 13;12:e85488. doi: 10.7554/eLife.85488.
Hippocampal ripples are highly synchronous neural events critical for memory consolidation and retrieval. A minority of strong ripples has been shown to be of particular importance in situations of increased memory demands. The propagation dynamics of strong ripples inside the hippocampal formation are, however, still opaque. We analyzed ripple propagation within the hippocampal formation in a large open-access dataset comprising 267 Neuropixel recordings in 49 awake, head-fixed mice. Surprisingly, strong ripples (top 10% in ripple strength) propagate differentially depending on their generation point along the hippocampal longitudinal axis. The septal hippocampal pole is able to generate longer ripples that engage more neurons and elicit spiking activity for an extended time even at considerable distances. Accordingly, a substantial portion of the variance in strong ripple duration (² = 0.463) is explained by the ripple generation location on the longitudinal axis, in agreement with a possible distinctive role of the hippocampal septal pole in conditions of high-memory demand. Moreover, we observed that the location of the ripple generation has a significant impact on the spiking rate modulation of different hippocampal subfields, even before the onset of the ripple. This finding suggests that ripple generation location plays a crucial role in shaping the neural activity across the hippocampus.
海马回波是高度同步的神经事件，对记忆巩固和提取至关重要。少数强回波被证明在记忆需求增加的情况下特别重要。然而，海马结构内强回波的传播动力学仍然不清楚。我们在一个包含 49 只清醒、头部固定的小鼠的 267 个 Neuropixel 记录的大型开放获取数据集内分析了海马回波的传播。令人惊讶的是，强回波（按回波强度的前 10%分类）根据它们在海马长轴上的生成点而具有不同的传播方式。隔区海马极能够产生更长的回波，这些回波能够在相当远的距离内吸引更多的神经元并引发更长时间的尖峰活动。因此，强回波持续时间的大部分方差（²=0.463）可以由长轴上的回波生成位置来解释，这与海马隔区极在高记忆需求条件下可能具有独特作用是一致的。此外，我们观察到，即使在回波开始之前，回波生成的位置对不同海马亚区的尖峰率调制也有显著影响。这一发现表明，回波生成的位置在塑造整个海马体的神经活动方面起着至关重要的作用。
