Deciphering the mechanisms of human memory is a central goal of neuroscience, both from the point of view of the fundamental biology of memory and for its translational relevance. Here, we review some contributions that recordings from neurons in humans implanted with electrodes for clinical purposes have made toward this goal. Recordings from the medial temporal lobe, including the hippocampus, reveal the existence of two classes of cells: those encoding highly selective and invariant representations of abstract concepts, and memory-selective cells whose activity is related to familiarity and episodic retrieval. Insights derived from observing these cells in behaving humans include that semantic representations are activated before episodic representations, that memory content and memory strength are segregated, and that the activity of both types of cells is related to subjective awareness as expected from a substrate for declarative memory. Visually selective cells can remain persistently active for several seconds, thereby revealing a cellular substrate for working memory in humans. An overarching insight is that the neural code of human memory is interpretable at the single-neuron level. Jointly, intracranial recording studies are starting to reveal aspects of the building blocks of human memory at the single-cell level. This work establishes a bridge to cellular-level work in animals on the one hand, and the extensive literature on noninvasive imaging in humans on the other hand. More broadly, this work is a step toward a detailed mechanistic understanding of human memory that is needed to develop therapies for human memory disorders.

从记忆的基本生物学和翻译相关性的角度来看，破译人类记忆的机制是神经科学的核心目标。在这里，我们回顾了为实现这一目标而植入电极的人体神经元记录的一些贡献。来自内侧颞叶（包括海马体）的记录揭示了两类细胞的存在：那些编码抽象概念的高度选择性和不变表示的细胞，以及其活动与熟悉度和情节提取相关的记忆选择性细胞。通过观察人类行为中的这些细胞获得的见解包括语义表征在情节表征之前被激活，记忆内容和记忆强度是分开的，并且这两种细胞的活动都与主观意识有关，正如对陈述性记忆的基质所预期的那样。视觉选择性细胞可以持续活跃几秒钟，从而揭示人类工作记忆的细胞基质。一个重要的见解是，人类记忆的神经代码可以在单神经元水平上进行解释。联合起来，颅内记录研究开始在单细胞水平上揭示人类记忆构建块的各个方面。这项工作一方面为动物的细胞水平工作建立了桥梁，另一方面是关于人类无创成像的大量文献。更广泛地说，这项工作是朝着对人类记忆的详细机械理解迈出的一步，这是开发人类记忆障碍疗法所需的。