High-frequency oscillations and sequence generation in two-population models of hippocampal region CA1.
High-frequency oscillations and sequence generation in two-population models of hippocampal region CA1.
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DOI：
10.1371/journal.pcbi.1009891
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发表时间：
2022-03
影响因子：
4.3
通讯作者：
Memmesheimer RM
中科院分区：
文献类型：
--
作者：
Braun W;Memmesheimer RM
海马尖波/涟漪振荡是一种显著的集体活动模式，它包括强烈的整体活动增加和叠加（140 − 200 Hz）的涟漪振荡。尽管它的突出和实验证明的记忆巩固的重要性，其产生的机制至今还不清楚。几个模型假设，抑制细胞的复发网络单独可以解释的涟漪振荡的产生和主要特征。然而，最近的实验表明，除了抑制篮细胞，该模式需要在体内的兴奋性锥体细胞的本地人口的活动。在这里，我们研究了一个模型，在海马区CA 1纳入这样一个局部兴奋性锥体神经元的人口网络。我们首先调查它的能力，使用广泛的模拟产生涟漪振荡。使用生物学上合理的参数，我们发现，短脉冲的外部激励触发兴奋性细胞尖峰所需的尖锐/波涟漪产生的振荡模式类似于在体内观察。我们的模型有合理的值为单个神经元，突触和连接参数，随机连接和没有强大的前馈驱动抑制人口。具体而言，而时间上广泛的激励可以导致高频振荡的涟漪范围内，稀疏的锥体细胞的活动，仅获得脉冲状的外部CA 3的激励。进一步的模拟表明，这种短脉冲可能源于树突棘在CA 1锥体细胞的顶端或基底树突，这是由一致的尖峰到达海马CA 3区触发。最后，我们表明，重放序列的锥体神经元和涟漪振荡可以产生固有的CA 1由于结构化的连接，引起交替兴奋性脉冲和抑制间隙编码;后者表示在特定的篮子细胞群，诱导选择性去抑制的锥体神经元群体的沉默阶段。这种序列生成的一般机制导致稀疏的锥体细胞和密集的篮状细胞尖峰，不依赖于synfire链状前馈激励，也可能与其他大脑区域相关。在睡眠、休息和完善行为的某些阶段，海马脑区产生强烈的高频振荡。这些振荡对记忆的形成和巩固很重要。迄今为止，其产生的机制仍不完全清楚。我们发现，在非结构化网络中，仔细设计如何在海马体内传输激励是产生强大的快速振荡所必需的。细胞的广泛的、时间上延长的激发导致不切实际的单细胞活动，而细胞与细胞之间不同的时间上窄的输入引起具有现实的单细胞和网络活动的振荡。我们表明，产生所需的时间窄的激发的生物物理机制可能与尖峰事件的树突，这是由重合的输入触发。我们在结构化网络中的研究结果表明，海马兴奋和抑制的相互作用可以作为一种手段来产生强大的序列活动，这被认为是记忆形成和回忆的关键。序列产生机制还导致强的高频振荡，具有稀疏的兴奋性细胞和频繁的抑制性细胞尖峰，如在海马中观察到的。
Hippocampal sharp wave/ripple oscillations are a prominent pattern of collective activity, which consists of a strong overall increase of activity with superimposed (140 − 200 Hz) ripple oscillations. Despite its prominence and its experimentally demonstrated importance for memory consolidation, the mechanisms underlying its generation are to date not understood. Several models assume that recurrent networks of inhibitory cells alone can explain the generation and main characteristics of the ripple oscillations. Recent experiments, however, indicate that in addition to inhibitory basket cells, the pattern requires in vivo the activity of the local population of excitatory pyramidal cells. Here, we study a model for networks in the hippocampal region CA1 incorporating such a local excitatory population of pyramidal neurons. We start by investigating its ability to generate ripple oscillations using extensive simulations. Using biologically plausible parameters, we find that short pulses of external excitation triggering excitatory cell spiking are required for sharp/wave ripple generation with oscillation patterns similar to in vivo observations. Our model has plausible values for single neuron, synapse and connectivity parameters, random connectivity and no strong feedforward drive to the inhibitory population. Specifically, whereas temporally broad excitation can lead to high-frequency oscillations in the ripple range, sparse pyramidal cell activity is only obtained with pulse-like external CA3 excitation. Further simulations indicate that such short pulses could originate from dendritic spikes in the apical or basal dendrites of CA1 pyramidal cells, which are triggered by coincident spike arrivals from hippocampal region CA3. Finally we show that replay of sequences by pyramidal neurons and ripple oscillations can arise intrinsically in CA1 due to structured connectivity that gives rise to alternating excitatory pulse and inhibitory gap coding; the latter denotes phases of silence in specific basket cell groups, which induce selective disinhibition of groups of pyramidal neurons. This general mechanism for sequence generation leads to sparse pyramidal cell and dense basket cell spiking, does not rely on synfire chain-like feedforward excitation and may be relevant for other brain regions as well. During certain phases of sleep, rest and consummatory behavior the hippocampus brain area generates strong high frequency oscillations. These oscillations are important for memory formation and consolidation. To date, the mechanisms underlying their generation remain incompletely understood. We find that in unstructured networks, carefully designing how excitation is transmitted within the hippocampus is required for the generation of robust fast oscillations. Broad, temporally extended excitation of cells results in unrealistic single cell activity, whereas temporally narrow input that differs from cell to cell gives rise to oscillations with realistic single cell and network activity. We show that the biophysical mechanism to generate the required temporally narrow excitation may be related to spiking events in the dendrites, which are triggered by coincident input. Our results in structured networks suggest that the interplay of hippocampal excitation and inhibition can serve as a means to generate robust sequential activity, which is thought to be crucial for memory formation and recall. The sequence generation mechanism also leads to strong high frequency oscillations with sparse excitatory cell and frequent inhibitory cell spiking, as observed in the hippocampus.
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影响因子：
3.5
作者：
Cheng S
通讯作者：
Cheng S
DOI：
10.1073/pnas.1103546108
发表时间：
2011-08-30
影响因子：
11.1
作者：
Baehner, Florian;Weiss, Elisa K.;Draguhn, Andreas
通讯作者：
Draguhn, Andreas
影响因子：
7.7
作者：
Bezaire, Marianne J.;Raikov, Ivan;Soltesz, Ivan
通讯作者：
Soltesz, Ivan
影响因子：
5.5
作者：
Ali, AB;Deuchars, J;Thomson, AM
通讯作者：
Thomson, AM
影响因子：
34.7
作者：
Buzsaki, Gyoergy;Mizuseki, Kenji
通讯作者：
Mizuseki, Kenji