Institute of Neuroscience, SyNergy Cluster and Center for Integrated Protein Science, Technical University Munich, 80802 Munich, Germany.
Proc Natl Acad Sci U S A. 2013 Aug 13;110(33):13618-23. doi: 10.1073/pnas.1312599110. Epub 2013 Jul 31.
Layer 5 pyramidal neurons process information from multiple cortical layers to provide a major output of cortex. Because of technical limitations it has remained unclear how these cells integrate widespread synaptic inputs located in distantly separated basal and tuft dendrites. Here, we obtained in vivo two-photon calcium imaging recordings from the entire dendritic field of layer 5 motor cortex neurons. We demonstrate that during subthreshold activity, basal and tuft dendrites exhibit spatially localized, small-amplitude calcium transients reflecting afferent synaptic inputs. During action potential firing, calcium signals in basal dendrites are linearly related to spike activity, whereas calcium signals in the tuft occur unreliably. However, in both dendritic compartments, spike-associated calcium signals were uniformly distributed throughout all branches. Thus, our data support a model of widespread, multibranch integration with a direct impact by basal dendrites and only a partial contribution on output signaling by the tuft.
第 5 层锥体神经元处理来自多个皮质层的信息，为皮质提供主要输出。由于技术限制，目前尚不清楚这些细胞如何整合位于远隔的基底和树突棘末梢的广泛突触输入。在这里，我们从运动皮层第 5 层的整个树突场获得了体内双光子钙成像记录。我们证明，在亚阈活动期间，基底和树突棘末梢表现出空间局部化的小幅度钙瞬变，反映传入的突触输入。在动作电位放电期间，基底树突中的钙信号与尖峰活动呈线性相关，而树突棘中的钙信号则不可靠地发生。然而，在两个树突区室中，与尖峰相关的钙信号均匀分布在所有分支中。因此，我们的数据支持一种广泛的多分支整合模型，基底树突直接影响输出信号，而树突棘末梢仅部分贡献输出信号。
