NMDA and GABAB (KIR) conductances: the "perfect couple" for bistability.
NMDA and GABAB (KIR) conductances: the "perfect couple" for bistability.
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DOI：
10.1523/jneurosci.1854-12.2013
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发表时间：
2013-01-09
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影响因子：
--
通讯作者：
Lisman JE
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文献类型：
--
作者：
Sanders H;Berends M;Major G;Goldman MS;Lisman JE
对新的输入模式产生持续放电的网络被认为在工作记忆和其他信息存储功能中很重要。维持持续放电的一个可能机制是树突电压双稳态，其中去极化状态取决于在复发性突触的NMDA电导的电压依赖性。在以前的模型中，超极化状态取决于电压无关电导，包括GABAA。这些电导的相互作用导致双稳态，但其鲁棒性受到电导比必须在窄范围内的事实的限制。在以前的分析中没有考虑抑制性传递的GABAB组分。在这里，我们表明，由GABAB受体激活的内向整流钾（KIR）电导的电压依赖性增加了大量的鲁棒性的网络模拟的双稳态和持久的射击，它的基础。超极化状态是稳健的，因为在超极化电位下，GABAB/KIR电导高而NMDA电导低;去极化状态是稳健的，因为在去极化电位下，NMDA电导高而GABAB/KIR电导低。我们的研究结果表明，这种互补的电压依赖性的GABAB/KIR和NMDA电导使他们成为一个“完美的夫妇”产生电压双稳态。
Networks that produce persistent firing in response to novel input patterns are thought to be important in working memory and other information storage functions. One possible mechanism for maintaining persistent firing is dendritic voltage bistability in which the depolarized state depends on the voltage dependence of the NMDA conductance at recurrent synapses. In previous models, the hyperpolarized state is dependent on voltage-independent conductances, including GABAA. The interplay of these conductances leads to bistability, but its robustness is limited by the fact that the conductance ratio must be within a narrow range. The GABAB component of inhibitory transmission was not considered in previous analyses. Here, we show that the voltage dependence of the inwardly rectifying potassium (KIR) conductance activated by GABAB receptors adds substantial robustness to network simulations of bistability and the persistent firing that it underlies. The hyperpolarized state is robust because, at hyperpolarized potentials, the GABAB/KIR conductance is high and the NMDA conductance is low; the depolarized state is robust because, at depolarized potentials, the NMDA conductance is high and the GABAB/KIR conductance is low. Our results suggest that this complementary voltage dependence of GABAB/KIR and NMDA conductances makes them a “perfect couple” for producing voltage bistability.