Higher-Order Synaptic Interactions Coordinate Dynamics in Recurrent Networks.
Higher-Order Synaptic Interactions Coordinate Dynamics in Recurrent Networks.
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DOI：
10.1371/journal.pcbi.1005078
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发表时间：
2016-08
影响因子：
4.3
通讯作者：
MacLean JN
中科院分区：
文献类型：
--
作者：
Chambers B;MacLean JN
将突触连通性与动力学联系起来是理解新皮层信息处理的关键。电路动力学产生于相互连接的神经元之间复杂的相互作用，因此需要在网络水平上评估连通性和动力学之间的联系。在这里，我们绘制了来自小鼠新皮层的大型神经元群的传播活动，并将其与循环网络模型进行比较，其中连通性可以精确测量和操纵。我们发现一个动态特征主导了新皮层和模型的传播活动的统计描述：由扇形三角形图案组成的收敛簇，其中两个输入神经元本身是连接的。扇形三角形在持续活动期间协调突触前输入的时间，以有效地产生突触后尖峰。结果，矛盾的是，扇形三角形甚至在随机连接的循环网络中也支配着尖峰传播的统计。高阶突触连通性与神经元的整合特性之间的相互作用制约了网络动力学的结构，并决定了信息在新皮层中的传递路径。活跃的神经元网络表现出超越两两的动态特征。在这项工作中，我们确定了网络动力学中的典型高阶相关性，并将其出现追溯到突触整合。我们发现，时间协调的放电优先发生在扇形三角形的位置，这是一个协调突触前时间的突触基序，导致突触后尖峰的可能性更大。扇向聚类的影响导致随机突触网络中出现非随机的尖峰路由。当突触权重在模拟中被人为地设置得更大时，合作输入就不那么重要了，动态不再由扇入三角形主导，而是更紧密地反映随机突触网络。因此，突触招募图中扇形聚类的出现是神经元网络中单个弱连接的集体特性。因为高阶的相互作用对于形成突触前输入的时间是必要的，所以活动不会均匀地通过突触网络传播。就像水在下坡时找到最深的通道一样，尖峰活动遵循阻力最小的路径，并通过连接的三重基序进行路由。这些结果表明，群集的扇入三角形是一个典型的网络基序和机制，在局部新皮层电路的spike路由。
Linking synaptic connectivity to dynamics is key to understanding information processing in neocortex. Circuit dynamics emerge from complex interactions of interconnected neurons, necessitating that links between connectivity and dynamics be evaluated at the network level. Here we map propagating activity in large neuronal ensembles from mouse neocortex and compare it to a recurrent network model, where connectivity can be precisely measured and manipulated. We find that a dynamical feature dominates statistical descriptions of propagating activity for both neocortex and the model: convergent clusters comprised of fan-in triangle motifs, where two input neurons are themselves connected. Fan-in triangles coordinate the timing of presynaptic inputs during ongoing activity to effectively generate postsynaptic spiking. As a result, paradoxically, fan-in triangles dominate the statistics of spike propagation even in randomly connected recurrent networks. Interplay between higher-order synaptic connectivity and the integrative properties of neurons constrains the structure of network dynamics and shapes the routing of information in neocortex. Active networks of neurons exhibit beyond-pairwise dynamical features. In this work, we identify a canonical higher-order correlation in network dynamics and trace its emergence to synaptic integration. We find that temporally coordinated firing preferentially occurs at sites of fan-in triangles—a synaptic motif which coordinates presynaptic timing, leading to greater likelihood of postsynaptic spiking. The influence of fan-in clustering leads to the surprising emergence of non-random routing of spiking in random synaptic networks. When synaptic weights are made artificially stronger in simulation, so that cooperative input is less crucial, dynamics are no longer dominated by fan-in triangles but instead more closely reflect the random synaptic network. Thus, the emergence of fan-in clustering in maps of synaptic recruitment is a collective property of individually weak connections in neuronal networks. Because higher-order interactions are necessary to shape the timing of presynaptic inputs, activity does not propagate uniformly through the synaptic network. Like water finding the deepest channels as it flows downhill, spiking activity follows the path of least resistance and is routed through triplet motifs of connectivity. These results argue that clustered fan-in triangles are a canonical network motif and mechanism for spike routing in local neocortical circuitry.