Talathi Sachin S, Hwang Dong-Uk, Carney Paul R, Ditto William L
J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA.
J Comput Neurosci. 2010 Apr;28(2):305-21. doi: 10.1007/s10827-009-0210-2. Epub 2010 Feb 6.
Recent experiments have shown that GABA(A) receptor mediated inhibition in adult hippocampus is shunting rather than hyperpolarizing. Simulation studies of realistic interneuron networks with strong shunting inhibition have been demonstrated to exhibit robust gamma band (20-80 Hz) synchrony in the presence of heterogeneity in the intrinsic firing rates of individual neurons in the network. In order to begin to understand how shunting can contribute to network synchrony in the presence of heterogeneity, we develop a general theoretical framework using spike time response curves (STRC's) to study patterns of synchrony in a simple network of two unidirectionally coupled interneurons (UCI network) interacting through a shunting synapse in the presence of heterogeneity. We derive an approximate discrete map to analyze the dynamics of synchronous states in the UCI network by taking into account the nonlinear contributions of the higher order STRC terms. We show how the approximate discrete map can be used to successfully predict the domain of synchronous 1:1 phase locked state in the UCI network. The discrete map also allows us to determine the conditions under which the two interneurons can exhibit in-phase synchrony. We conclude by demonstrating how the information from the study of the discrete map for the dynamics of the UCI network can give us valuable insight into the degree of synchrony in a larger feed-forward network of heterogeneous interneurons.
最近的实验表明，成年海马体中γ-氨基丁酸A（GABA(A)）受体介导的抑制作用是分流性的，而非超极化性的。对具有强分流抑制作用的真实中间神经元网络进行的模拟研究表明，在网络中单个神经元的固有放电率存在异质性的情况下，该网络会表现出强大的γ波段（20 - 80赫兹）同步性。为了开始理解在存在异质性的情况下分流如何促进网络同步，我们开发了一个通用的理论框架，使用峰电位时间响应曲线（STRC's）来研究一个简单的单向耦合中间神经元网络（UCI网络）在存在异质性且通过分流突触相互作用时的同步模式。我们通过考虑高阶STRC项的非线性贡献，推导出一个近似离散映射来分析UCI网络中同步状态的动力学。我们展示了如何使用该近似离散映射成功预测UCI网络中同步1:1锁相状态的区域。该离散映射还使我们能够确定两个中间神经元能够表现出同相同步的条件。我们通过证明对UCI网络动力学的离散映射研究所得信息如何能让我们深入了解更大的异质中间神经元前馈网络中的同步程度来结束本文。
