Altered phase precession and compression of temporal sequences by place cells in epileptic rats
Altered phase precession and compression of temporal sequences by place cells in epileptic rats
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DOI：
10.1523/jneurosci.5024-07.2008
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发表时间：
2008-05-07
影响因子：
5.3
通讯作者：
Holmes, Gregory L.
中科院分区：
文献类型：
--
作者：
Lenck-Santini, Pierre-Pascal;Holmes, Gregory L.
在海马体中，锥体细胞以两种主要方式编码信息：速率编码和时间编码。速率编码，其中信息通过激发频率编码，示例性地由位置细胞示出，其特征在于它们的位置特异性激发。此外，多个位置细胞的精确时间组织在压缩的时间窗口中提供了关于动物访问的位置的时间序列的信息。这种编码是通过相位进动完成的，相位进动是一种将单位放电与θ节律联系起来的现象，θ节律是主要的海马EEG振荡之一。虽然这种类型的处理可能对正常的大脑功能至关重要，但其参与与认知障碍相关的病理尚不清楚。在这个实验中，我们确定了位置细胞放电的时间组织是否在内侧颞叶癫痫（MTLE）的动物模型中受到影响，MTLE是一种伴有认知障碍的疾病。我们研究了癫痫持续状态（SE）后大鼠海马编码及其与θ节律的关系，SE是导致MTLE的一种情况。我们发现，SE大鼠的位置细胞中有很大比例的异常相位/进动模式和时间组织之间的神经元放电，这构成了时间序列的压缩，被改变。同样的动物在水迷宫任务中也明显受损，这是一种空间记忆的测量方法。我们提出，在MTLE中观察到的突触和细胞改变诱导海马中的异常时间编码，进而导致认知功能障碍。
In the hippocampus, pyramidal cells encode information in two major ways: rate coding and temporal coding. Rate coding, in which information is coded through firing frequency, is exemplarily illustrated by place cells, characterized by their location-specific firing. In addition, the precise temporal organization of firing of multiple place cells provides information, in a compressed time window, about the temporal sequence of the locations visited by the animal. This encoding is accomplished through phase precession, a phenomenon whereby unit firing is linked to theta rhythm, one of the major hippocampal EEG oscillations. Although it is likely that this type of processing is critical for normal brain function, its involvement in pathologies associated with cognitive disorders is unknown. In this experiment, we determined whether the temporal organization of place cell firing is affected in an animal model of mesial temporal lobe epilepsy (MTLE), a disease accompanied with cognitive impairment. We investigated hippocampal coding and its relationship to theta rhythm in rats after status epilepticus (SE), a condition that leads to MTLE. We found a great proportion of SE place cells had aberrant phase/precession pattern and temporal organization of firing among pairs of neurons, which constitutes the compression of temporal sequences, was altered in SE rats. The same animals were also markedly impaired in the water maze task, a measure of spatial memory. We propose that the synaptic and cellular alterations observed in MTLE induce aberrant temporal coding in the hippocampus, contributing in turn to cognitive dysfunction.