Hippocampal Network Dynamics Constrain the Time Lag between Pyramidal Cells across Modified Environments
Hippocampal Network Dynamics Constrain the Time Lag between Pyramidal Cells across Modified Environments
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DOI：
10.1523/jneurosci.3824-08.2008
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发表时间：
2008-12-10
影响因子：
5.3
通讯作者：
Buzsaki, Gyoergy
中科院分区：
文献类型：
--
作者：
Diba, Kamran;Buzsaki, Gyoergy
海马体提供了环境的空间图。环境的变化会改变海马神经元的放电模式，但可能会受到网络动态元素的限制。我们比较了大鼠在直线跑道上为水奖赏而跑步时，缩短跑道长度前后海马CA 1和CA 3区的神经活动。一小部分细胞失去了它们的位置场，新的带场细胞组出现了，表明两个轨道的不同表示。在这两种环境中活跃的细胞都会以位置依赖性的方式移动它们的位置场，最明显的是在轨迹的开始和结束处。此外，峰值放电率和位置场的大小下降，而位置场重叠和协同性增加。在CA 1和CA 3中，局部场电位的θ频带中的功率也随着两个结构之间的相干性而沿着降低。相比之下，细胞对之间的θ尺度（0-150 ms）时间滞后（代表轨道上的距离）是保守的，抑制性神经元群体的活性在整个环境中得以维持。我们将这些观察结果解释为反映了海马网络动力学的自由和约束。自由度允许网络具有必要的灵活性，以清楚地表示独特的模式，而动力学约束了活动在表示模式的单元组件之间传播的速度。
The hippocampus provides a spatial map of the environment. Changes in the environment alter the firing patterns of hippocampal neurons, but are presumably constrained by elements of the network dynamics. We compared the neural activity in CA1 and CA3 regions of the hippocampus in rats running for water reward on a linear track, before and after the track length was shortened. A fraction of cells lost their place fields and new sets of cells with fields emerged, indicating distinct representation of the two tracks. Cells active in both environments shifted their place fields in a location-dependent manner, most notably at the beginning and the end of the track. Furthermore, peak firing rates and place-field sizes decreased, whereas place-field overlap and coactivity increased. Power in the theta-frequency band of the local field potentials also decreased in both CA1 and CA3, along with the coherence between the two structures. In contrast, the theta-scale (0-150 ms) time lags between cell pairs, representing distances on the tracks, were conserved, and the activity of the inhibitory neuron population was maintained across environments. We interpret these observations as reflecting the freedoms and constraints of the hippocampal network dynamics. The freedoms permit the necessary flexibility for the network to distinctly represent unique patterns, whereas the dynamics constrain the speed at which activity propagates between the cell assemblies representing the patterns.