Department of Neuroscience, Columbia University, New York, NY, USA; Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
Allen Institute for Brain Science, Seattle, WA, USA; Department of Computer Science, University of Georgia, Athens, GA, USA.
Neuron. 2020 May 20;106(4):566-578.e8. doi: 10.1016/j.neuron.2020.02.015. Epub 2020 Mar 12.
The balance between excitatory and inhibitory (E and I) synapses is thought to be critical for information processing in neural circuits. However, little is known about the spatial principles of E and I synaptic organization across the entire dendritic tree of mammalian neurons. We developed a new open-source reconstruction platform for mapping the size and spatial distribution of E and I synapses received by individual genetically-labeled layer 2/3 (L2/3) cortical pyramidal neurons (PNs) in vivo. We mapped over 90,000 E and I synapses across twelve L2/3 PNs and uncovered structured organization of E and I synapses across dendritic domains as well as within individual dendritic segments. Despite significant domain-specific variation in the absolute density of E and I synapses, their ratio is strikingly balanced locally across dendritic segments. Computational modeling indicates that this spatially precise E/I balance dampens dendritic voltage fluctuations and strongly impacts neuronal firing output.
兴奋性和抑制性（E 和 I）突触之间的平衡被认为对神经回路中的信息处理至关重要。然而，对于哺乳动物神经元整个树突中 E 和 I 突触的空间组织原则知之甚少。我们开发了一种新的开源重建平台，用于映射个体基因标记的 2/3 层（L2/3）皮质锥体神经元（PN）在体内接收的 E 和 I 突触的大小和空间分布。我们对 12 个 L2/3PN 中的 90,000 多个 E 和 I 突触进行了映射，揭示了 E 和 I 突触在树突域以及单个树突段内的结构组织。尽管 E 和 I 突触的绝对密度在域内有显著变化，但它们在树突段内的局部比值惊人地平衡。计算模型表明，这种空间上精确的 E/I 平衡可以抑制树突电压波动，并对神经元放电输出产生强烈影响。
