Experience-driven rate modulation is reinstated during hippocampal replay.
Experience-driven rate modulation is reinstated during hippocampal replay.
复制标题
DOI：
10.7554/elife.79031
复制
发表时间：
2022-08-22
期刊：
影响因子：
7.7
通讯作者：
Bendor, Daniel
中科院分区：
文献类型：
--
作者：
Tirole, Margot;Huelin Gorriz, Marta;Takigawa, Masahiro;Kukovska, Lilia;Bendor, Daniel
重放，神经元整体内的顺序再激活，是一种被假设为驱动记忆处理的中央海马机制。虽然海马位置细胞使用速率和位置表征来编码行为事件，但重放在很大程度上仅由后者定义-基于相邻位置区域的顺序活动的保真度。在这里，我们表明，背侧CA 1的地方细胞在大鼠可以调节其放电率之间的两个不同的情况下重放事件。这种依赖经验的现象反映了在行为过程中观察到的相同的速率调制模式，并且可以独立于重放序列内的位置信息来区分上下文。我们的研究结果揭示了存在两个互补的神经表征可用于记忆过程。我们的大脑是如何储存记忆的？我们现在知道这是一个复杂而动态的过程，涉及大脑的多个区域。大脑中一个叫做海马体的区域在记忆的形成中起着重要的作用。当我们睡觉时，海马体会巩固信息，并最终产生稳定的长期记忆，然后存储在大脑的其他部分。但海马体是如何做到这一点的呢？神经科学家认为，它可以重放代表特定记忆的大脑活动模式。通过在我们睡觉时重复这样做，海马体可以将这些信息转移到大脑的其他部分进行存储。大脑中神经细胞的行为是这些大脑活动模式的基础。当神经细胞活跃时，它会发出微小的电脉冲，这些电脉冲可以通过实验检测到。因此，大脑以两种方式表示信息：哪些神经细胞活跃以及何时活跃（顺序模式）;以及神经细胞的活跃程度（它们发射电脉冲或发射率的速度）。例如，当动物从一个位置移动到另一个位置时，海马体中的特殊位置细胞会以不同的顺序变得活跃。根据上下文，它们也会更快或更慢地发射。我们知道海马体可以在记忆巩固过程中重放神经细胞活动的顺序模式，但它是否也可以重放与特定经历相关的放电率仍然是未知的。Tirole，Huelin Gorriz等人开始确定海马是否也可以在重放过程中保留由放电率编码的信息。在实验中，老鼠探索了两种他们从未见过的不同环境。研究人员记录了老鼠在探索之前、之后以及之后睡觉时的位置细胞活动。对记录的分析显示，在重放过程中，大鼠的前额叶皮层确实可以再现活动的顺序模式和位置细胞的放电频率。它还证实了每个环境都与独特的放电率相关-换句话说，放电率是记忆特定的。这些结果有助于我们理解海马体如何代表和处理我们的经验信息。更广泛地说，他们还揭示了大脑如何储存记忆，揭示了大脑用来巩固这些信息的机制的关键部分。
Replay, the sequential reactivation within a neuronal ensemble, is a central hippocampal mechanism postulated to drive memory processing. While both rate and place representations are used by hippocampal place cells to encode behavioral episodes, replay has been largely defined by only the latter – based on the fidelity of sequential activity across neighboring place fields. Here, we show that dorsal CA1 place cells in rats can modulate their firing rate between replay events of two different contexts. This experience-dependent phenomenon mirrors the same pattern of rate modulation observed during behavior and can be used independently from place information within replay sequences to discriminate between contexts. Our results reveal the existence of two complementary neural representations available for memory processes. How do our brains store memories? We now know that this is a complex and dynamic process, involving multiple regions of the brain. A brain region, called the hippocampus, plays an important role in memory formation. While we sleep, the hippocampus works to consolidate information, and eventually creates stable, long-term memories that are then stored in other parts of the brain. But how does the hippocampus do this? Neuroscientists believe that it can replay the patterns of brain activity that represent particular memories. By repeatedly doing this while we sleep, the hippocampus can then direct the transfer of this information to the rest of the brain for storage. The behaviour of nerve cells in the brain underpins these patterns of brain activity. When a nerve cell is active, it fires tiny electrical impulses that can be detected experimentally. The brain thus represents information in two ways: which nerve cells are active and when (sequential patterns); and how active the nerve cells are (how fast they fire electrical impulses or firing rate). For example, when an animal moves from one location to another, special place cells in the hippocampus become active in a distinct sequence. Depending on the context, they will also fire faster or slower. We know that the hippocampus can replay sequential patterns of nerve cell activity during memory consolidation, but whether it can also replay the firing rates associated with a particular experience is still unknown. Tirole, Huelin Gorriz et al. set out to determine if the hippocampus could also preserve the information encoded by firing rate during replay. In the experiments, rats explored two different environments that they had not seen before. The activity of the rats’ place cells was recorded before and after they explored, and also later while they were sleeping. Analysis of the recordings revealed that during replay, the rats’ hippocampi could indeed reproduce both the sequential patterns of activity and the firing rate of the place cells. It also confirmed that each environment was associated with unique firing rates – in other words, the firing rates were memory-specific. These results contribute to our understanding of how the hippocampus represents and processes information about our experiences. More broadly, they also shed new light on how the brain lays down memories, by revealing a key part of the mechanism that it uses to consolidate that information.