Committee on Computational Neuroscience.
Committee on Computational Neuroscience, Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
J Neurosci. 2014 Jun 4;34(23):7769-77. doi: 10.1523/JNEUROSCI.0169-14.2014.
Spiking correlations between neocortical neurons provide insight into the underlying synaptic connectivity that defines cortical microcircuitry. Here, using two-photon calcium fluorescence imaging, we observed the simultaneous dynamics of hundreds of neurons in slices of mouse primary visual cortex (V1). Consistent with a balance of excitation and inhibition, V1 dynamics were characterized by a linear scaling between firing rate and circuit size. Using lagged firing correlations between neurons, we generated functional wiring diagrams to evaluate the topological features of V1 microcircuitry. We found that circuit connectivity exhibited both cyclic graph motifs, indicating recurrent wiring, and acyclic graph motifs, indicating feedforward wiring. After overlaying the functional wiring diagrams onto the imaged field of view, we found properties consistent with Rentian scaling: wiring diagrams were topologically efficient because they minimized wiring with a modular architecture. Within single imaged fields of view, V1 contained multiple discrete circuits that were overlapping and highly interdigitated but were still distinct from one another. The majority of neurons that were shared between circuits displayed peri-event spiking activity whose timing was specific to the active circuit, whereas spike times for a smaller percentage of neurons were invariant to circuit identity. These data provide evidence that V1 microcircuitry exhibits balanced dynamics, is efficiently arranged in anatomical space, and is capable of supporting a diversity of multineuron spike firing patterns from overlapping sets of neurons.
皮质神经元的尖峰相关性提供了对定义皮质微电路的潜在突触连接的深入了解。在这里，我们使用双光子钙荧光成像技术，观察了小鼠初级视觉皮层（V1）切片中数百个神经元的同步动力学。与兴奋和抑制的平衡一致，V1 的动力学特征是放电率和电路大小之间的线性比例关系。我们利用神经元之间的滞后放电相关性，生成功能布线图来评估 V1 微电路的拓扑特征。我们发现，电路连接既表现出循环图模式，表明存在递归连接，又表现出非循环图模式，表明存在前馈连接。在将功能布线图叠加到成像视场后，我们发现了与 Rentian 缩放一致的性质：布线图具有拓扑效率，因为它们以模块化架构最小化布线。在单个成像视场中，V1 包含多个重叠且高度交织的离散电路，但彼此之间仍然明显不同。在电路之间共享的大多数神经元表现出与事件相关的尖峰活动，其时间与活动电路特定，而一小部分神经元的尖峰时间与电路身份无关。这些数据提供了证据表明 V1 微电路表现出平衡的动力学，在解剖空间中得到有效排列，并能够支持来自重叠神经元集的多种多神经元尖峰发射模式。
