Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 733 N Broadway, Baltimore, MD 21205, USA; Department of Neurobiology and Neuroscience Institute, University of Chicago, 5801 S Ellis Avenue, Chicago, IL 60637, USA.
Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA.
Curr Biol. 2022 Mar 14;32(5):1088-1101.e5. doi: 10.1016/j.cub.2022.01.023. Epub 2022 Feb 1.
The hippocampus is involved in the formation of memories that require associations among stimuli to construct representations of space and the items and events within that space. Neurons in the dentate gyrus (DG), an initial input region of the hippocampus, have robust spatial tuning, but it is unclear how nonspatial information may be integrated with spatial activity in this region. We recorded from the DG of 21 adult mice as they foraged for food in an environment that contained discrete objects. We found DG cells with multiple firing fields at a fixed distance and direction from objects (landmark vector cells) and cells that exhibited localized changes in spatial firing when objects in the environment were manipulated. By classifying recorded DG cells into putative dentate granule cells and mossy cells, we examined how the addition or displacement of objects affected the spatial firing of these DG cell types. Object-related activity was detected in a significant proportion of mossy cells. Although few granule cells with responses to object manipulations were recorded, likely because of the sparse nature of granule cell firing, there was generally no significant difference in the proportion of granule cells and mossy cells with object responses. When mice explored a second environment with the same objects, DG spatial maps completely reorganized, and a different subset of cells responded to object manipulations. Together, these data reveal the capacity of DG cells to detect small changes in the environment while preserving a stable spatial representation of the overall context.
海马体参与了需要在刺激之间建立关联以构建空间以及该空间内的项目和事件的记忆的形成。海马体的初始输入区域齿状回（DG）中的神经元具有很强的空间调谐能力，但尚不清楚该区域中的非空间信息如何与空间活动相整合。当 21 只成年小鼠在包含离散物体的环境中觅食时，我们对其 DG 进行了记录。我们发现 DG 细胞在与物体（地标向量细胞）固定距离和方向处具有多个发射场，并且当环境中的物体被操纵时，细胞的空间发射会发生局部变化。通过将记录的 DG 细胞分类为假定的颗粒细胞和苔藓细胞，我们研究了物体的添加或位移如何影响这些 DG 细胞类型的空间发射。在很大一部分苔藓细胞中检测到与物体相关的活动。尽管记录到的对物体操作有反应的颗粒细胞很少，可能是因为颗粒细胞发射的稀疏性，但对物体有反应的颗粒细胞和苔藓细胞的比例通常没有显著差异。当小鼠探索具有相同物体的第二个环境时，DG 空间图谱完全重新组织，并且不同的细胞子集对物体操作做出响应。这些数据共同揭示了 DG 细胞在保持整体环境的稳定空间表示的同时检测环境中微小变化的能力。
