Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
Neuron. 2016 Mar 2;89(5):1016-30. doi: 10.1016/j.neuron.2016.01.029. Epub 2016 Feb 18.
Neuronal circuit function is governed by precise patterns of connectivity between specialized groups of neurons. The diversity of GABAergic interneurons is a hallmark of cortical circuits, yet little is known about their targeting to individual postsynaptic dendrites. We examined synaptic connectivity between molecularly defined inhibitory interneurons and CA1 pyramidal cell dendrites using correlative light-electron microscopy and large-volume array tomography. We show that interneurons can be highly selective in their connectivity to specific dendritic branch types and, furthermore, exhibit precisely targeted connectivity to the origin or end of individual branches. Computational simulations indicate that the observed subcellular targeting enables control over the nonlinear integration of synaptic input or the initiation and backpropagation of action potentials in a branch-selective manner. Our results demonstrate that connectivity between interneurons and pyramidal cell dendrites is more precise and spatially segregated than previously appreciated, which may be a critical determinant of how inhibition shapes dendritic computation.
神经元回路的功能由特定神经元群之间精确的连接模式所控制。γ-氨基丁酸能中间神经元的多样性是皮质回路的一个标志，但它们对单个突触后树突的靶向作用知之甚少。我们使用相关的光电子显微镜和大容量阵列断层扫描技术，研究了分子定义的抑制性中间神经元与 CA1 锥体神经元树突之间的突触连接。我们表明，中间神经元在与特定树突分支类型的连接上具有高度选择性，并且进一步表现出对单个分支的起源或末端的精确靶向连接。计算模拟表明，观察到的亚细胞靶向可以以分支选择性的方式控制突触输入的非线性整合或动作电位的起始和逆行传播。我们的结果表明，中间神经元和锥体神经元树突之间的连接比以前认为的更加精确和空间分离，这可能是抑制作用如何塑造树突计算的关键决定因素。
