The dynamic range of bursting in a model respiratory pacemaker network
The dynamic range of bursting in a model respiratory pacemaker network
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DOI：
10.1137/050625540
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发表时间：
2005-01-01
影响因子：
2.1
通讯作者：
Wechselberger, M
中科院分区：
文献类型：
--
作者：
Best, J;Borisyuk, A;Wechselberger, M
实验发现，哺乳动物脑干的前 Botzinger 复合体（前 BotC）内的兴奋性神经元网络可以产生强大、同步的群体活动爆发。 BotC 前细胞的实验校准模型在没有耦合的情况下，在一定的参数范围内产生典型的方波爆发行为，在该范围之外有静止或强直尖峰。该模型之前的模拟表明，突触耦合的引入显着扩展了突发参数范围，并对突发特性产生了复杂的影响。在本文中，我们使用几何动力系统技术，主要是快/慢分解和分叉分析方法，来解释两细胞模型网络中的这些影响。我们的分析得出了一个新颖的发现，即在广泛的突触耦合强度范围内，网络可以支持两种性质不同的同步爆发形式，我们称之为对称和不对称爆发，以及对称和不对称的强直尖峰。通过阐明这些状态之间转换的动力学机制，我们还深入了解相关参数如何影响突发持续时间和突发间间隔。我们发现，在具有突触耦合的两细胞网络中，快速子系统的稳定周期轨道族在同步突发中具有尖峰异步性，并且在较宽的参数范围内以鞍节点分叉而不是同宿分叉终止。因此，方波爆发被我们所说的顶帽爆发（也称为折叠/折叠循环爆发）所取代，至少对于大范围的参数值而言是如此。此外，尖峰异步是塑造突发动态范围的关键因素，导致突发发生的参数范围显着增强，并且随着适当参数的变化，突发持续时间突然增加。
A network of excitatory neurons within the pre-Botzinger complex (pre-BotC) of the mammalian brain stem has been found experimentally to generate robust, synchronized population bursts of activity. An experimentally calibrated model for pre-BotC cells yields typical square-wave bursting behavior in the absence of coupling, over a certain parameter range, with quiescence or tonic spiking outside of this range. Previous simulations of this model showed that the introduction of synaptic coupling extends the bursting parameter range significantly and induces complex effects on burst characteristics. In this paper, we use geometric dynamical systems techniques, predominantly a fast/slow decomposition and bifurcation analysis approach, to explain these effects in a two-cell model network. Our analysis yields the novel finding that, over a broad range of synaptic coupling strengths, the network can support two qualitatively distinct forms of synchronized bursting, which we call symmetric and asymmetric bursting, as well as both symmetric and asymmetric tonic spiking. By elucidating the dynamical mechanisms underlying the transitions between these states, we also gain insight into how relevant parameters influence burst duration and interburst intervals. We find that, in the two-cell network with synaptic coupling, the stable family of periodic orbits for the fast subsystem features spike asynchrony within otherwise synchronized bursts and terminates in a saddle-node bifurcation, rather than in a homoclinic bifurcation, over a wide parameter range. As a result, square-wave bursting is replaced by what we call top hat bursting ( also known as fold/fold cycle bursting), at least for a broad range of parameter values. Further, spike asynchrony is a key ingredient in shaping the dynamic range of bursting, leading to a significant enhancement in the parameter range over which bursting occurs and an abrupt increase in burst duration as an appropriate parameter is varied.