Pala Aurélie, Petersen Carl C H
Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
Neuron. 2015 Jan 7;85(1):68-75. doi: 10.1016/j.neuron.2014.11.025. Epub 2014 Dec 24.
Intracellular recordings of membrane potential in vitro have defined fundamental properties of synaptic communication. Much less is known about the properties of synaptic connectivity and synaptic transmission in vivo. Here, we combined single-cell optogenetics with whole-cell recordings to investigate glutamatergic synaptic transmission in vivo from single identified excitatory neurons onto two genetically defined subtypes of inhibitory GABAergic neurons in layer 2/3 mouse barrel cortex. We found that parvalbumin-expressing (PV) GABAergic neurons received unitary glutamatergic synaptic input with higher probability than somatostatin-expressing (Sst) GABAergic neurons. Unitary excitatory postsynaptic potentials onto PV neurons were also faster and more reliable than inputs onto Sst neurons. Excitatory synapses targeting Sst neurons displayed strong short-term facilitation, while those targeting PV neurons showed little short-term dynamics. Our results largely agree with in vitro measurements. We therefore demonstrate the technical feasibility of assessing functional cell-type-specific synaptic connectivity in vivo, allowing future investigations into context-dependent modulation of synaptic transmission.
体外膜电位的细胞内记录已明确了突触通讯的基本特性。对于体内突触连接和突触传递的特性了解得则少得多。在这里，我们将单细胞光遗传学与全细胞记录相结合，以研究在体情况下，从单个已鉴定的兴奋性神经元到小鼠桶状皮质第2/3层中两种基因定义的抑制性GABA能神经元亚型上的谷氨酸能突触传递。我们发现，表达小白蛋白（PV）的GABA能神经元比表达生长抑素（Sst）的GABA能神经元更有可能接受单一的谷氨酸能突触输入。作用于PV神经元的单一兴奋性突触后电位也比作用于Sst神经元的输入更快且更可靠。靶向Sst神经元的兴奋性突触表现出强烈的短期易化，而靶向PV神经元的突触则几乎没有短期动态变化。我们的结果在很大程度上与体外测量结果一致。因此，我们证明了在体内评估功能性细胞类型特异性突触连接的技术可行性，这为未来研究突触传递的背景依赖性调节提供了可能。
