Modeling Inheritance of Phase Precession in the Hippocampal Formation
Modeling Inheritance of Phase Precession in the Hippocampal Formation
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DOI：
10.1523/jneurosci.5136-13.2014
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发表时间：
2014-05-28
影响因子：
5.3
通讯作者：
Kempter, Richard
中科院分区：
文献类型：
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作者：
Jaramillo, Jorge;Schmidt, Robert;Kempter, Richard
有关环境的空间信息由海马结构中的位置细胞和网格细胞的活动编码。当动物穿过细胞的放电场时，动作电位逐渐转移到 theta 振荡的早期阶段（6-10 Hz）。这种“相位进动”也在前额皮质和腹侧纹状体中观察到，但其产生机制尚不清楚。然而，一旦某一区域存在相位进动，它也可能传播到下游区域。使用计算模型，我们分析了相位进动的这种继承，例如从内嗅皮层到 CA1 以及从 CA3 到 CA1。我们发现 CA1 锥体细胞膜电位的独特阈下和阈上特征（Harvey 等，2009；Mizuseki 等，2012；Royer 等，2012）可以通过遗传来解释，并且兴奋性输入是必不可少的。该模型解释了抑制如何调节相位进动的斜率和范围，并提供了两个主要的可测试预测。首先，CA1 锥体细胞的 θ 调制抑制输入对于相位进动来说并不是必需的。其次，θ 调节的抑制输入本身会产生与细胞外场的峰值同相的膜电位峰值。此外，我们认为相位进动输入单元群体的场中心的空间分布不仅决定了位置选择性，还决定了目标输出单元的相位进动特征。因此，遗传模型可以解释为什么在整个海马结构和大脑其他区域观察到相位进动。
Spatial information about the environment is encoded by the activity of place and grid cells in the hippocampal formation. As an animal traverses a cell's firing field, action potentials progressively shift to earlier phases of the theta oscillation (6-10 Hz). This "phase precession" is observed also in the prefrontal cortex and the ventral striatum, but mechanisms for its generation are unknown. However, once phase precession exists in one region, it might also propagate to downstream regions. Using a computational model, we analyze such inheritance of phase precession, for example, from the entorhinal cortex to CA1 and from CA3 to CA1. We find that distinctive subthreshold and suprathreshold features of the membrane potential of CA1 pyramidal cells (Harvey et al., 2009; Mizuseki et al., 2012; Royer et al., 2012) can be explained by inheritance and that excitatory input is essential. The model explains how inhibition modulates the slope and range of phase precession and provides two main testable predictions. First, theta-modulated inhibitory input to a CA1 pyramidal cell is not necessary for phase precession. Second, theta-modulated inhibitory input on its own generates membrane potential peaks that are in phase with peaks of the extracellular field. Furthermore, we suggest that the spatial distribution of field centers of a population of phase-precessing input cells determines, not only the place selectivity, but also the characteristics of phase precession of the targeted output cell. The inheritance model thus can explain why phase precession is observed throughout the hippocampal formation and other areas of the brain.