Department of Biological Sciences, Neurotechnology Center, Columbia University, NY, USA.
Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.
Cereb Cortex. 2019 Jul 5;29(7):2771-2781. doi: 10.1093/cercor/bhy143.
The location of GABAergic synapses on dendrites is likely key for neuronal integration. In particular, inhibitory inputs on dendritic spines could serve to selectively veto or modulate individual excitatory inputs, greatly expanding the computational power of individual neurons. To investigate this, we have undertaken a combined functional, molecular, and ultrastructural mapping of the location of GABAergic inputs onto dendrites of pyramidal neurons from upper layers of juvenile mouse somatosensory cortex. Using two-photon uncaging of GABA, intracellular labeling with gerphyrin intrabodies, and focused ion beam milling with scanning electron microscopy, we find that most (96-98%) spines lack GABAergic synapses, although they still display GABAergic responses, potentially due to extrasynaptic GABA receptors. We conclude that GABAergic inputs, in practice, contact dendritic shafts and likely control clusters of excitatory inputs, defining functional zones on dendrites.
GABA 能突触在树突上的位置可能对神经元整合至关重要。特别是，树突棘上的抑制性输入可能用于选择性否决或调节单个兴奋性输入，从而极大地扩展单个神经元的计算能力。为了研究这一点，我们对来自幼年小鼠体感皮层上层的锥体神经元的树突上 GABA 能输入的位置进行了功能、分子和超微结构的综合映射。我们使用双光子光解 GABA、Gephyrin 内抗体的细胞内标记和聚焦离子束铣削与扫描电子显微镜，发现大多数（96-98%）的棘突缺乏 GABA 能突触，但它们仍然显示 GABA 能反应，可能是由于存在突触外 GABA 受体。我们得出结论，GABA 能输入实际上与树突干接触，并可能控制兴奋性输入簇，从而在树突上定义功能区。
