Membrane potential dynamics of grid cells.
Membrane potential dynamics of grid cells.
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在导航过程中，网格细胞在排列在一个非常规则的三角形网格上的发射场中增加了它们的尖峰频率，而它们的尖峰时间往往受到θ振荡的调制。振荡干扰模型的网格细胞预测θ振幅调制的膜电位在射击场穿越，而竞争吸引子网络模型预测缓慢的去极化斜坡。在这里，使用体内全细胞记录，我们通过直接测量小鼠在虚拟现实中沿着沿着线性轨道运行的网格细胞胞内电位来测试这些模型。网格细胞具有大的和可重复的膜电位去极化的斜坡，这是与发射场密切相关的特征签名。网格细胞也表现出细胞内θ振荡，影响其尖峰时间。然而，θ振幅调制的特性与它们决定发射场位置的观点不一致。我们的研究结果支持细胞和网络机制，其中网格领域产生的缓慢斜坡，在吸引模型，而θ振荡控制尖峰时间。
During navigation, grid cells increase their spike rates in firing fields arranged on a strikingly regular triangular lattice, while their spike timing is often modulated by theta oscillations. Oscillatory interference models of grid cells predict theta amplitude modulations of membrane potential during firing field traversals, while competing attractor network models predict slow depolarizing ramps. Here, using in-vivo whole-cell recordings, we tested these models by directly measuring grid cell intracellular potentials in mice running along linear tracks in virtual reality. Grid cells had large and reproducible ramps of membrane potential depolarization that were the characteristic signature tightly correlated with firing fields. Grid cells also exhibited intracellular theta oscillations that influenced their spike timing. However, the properties of theta amplitude modulations were not consistent with the view that they determine firing field locations. Our results support cellular and network mechanisms in which grid fields are produced by slow ramps, as in attractor models, while theta oscillations control spike timing.