State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, 19 Xinjiekou Wai Street, Beijing, 100875, China.
Institute of Neuroscience and State Key Laboratory of Neuroscience, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, 200031, China.
Nat Commun. 2018 Nov 20;9(1):4890. doi: 10.1038/s41467-018-07317-4.
Autapses are synaptic contacts of a neuron's axon onto its own dendrite and soma. In the neocortex, self-inhibiting autapses in GABAergic interneurons are abundant in number and play critical roles in regulating spike precision and network activity. Here we examine whether the principal glutamatergic pyramidal cells (PCs) also form functional autapses. In patch-clamp recording from both rodent and human PCs, we isolated autaptic responses and found that these occur predominantly in layer-5 PCs projecting to subcortical regions, with very few in those projecting to contralateral prefrontal cortex and layer 2/3 PCs. Moreover, PC autapses persist during development into adulthood. Surprisingly, they produce giant postsynaptic responses (∼5 fold greater than recurrent PC-PC synapses) that are exclusively mediated by AMPA receptors. Upon activation, autapses enhance burst firing, neuronal responsiveness and coincidence detection of synaptic inputs. These findings indicate that PC autapses are functional and represent an important circuit element in the neocortex.
自突触是神经元轴突与自身树突和胞体的突触接触。在新皮层中， GABA 能中间神经元的自我抑制性自突触数量丰富，在调节尖峰精度和网络活动方面发挥着关键作用。在这里，我们研究了主要的谷氨酸能锥体神经元 (PCs) 是否也形成功能性自突触。在来自啮齿动物和人类 PCs 的膜片钳记录中，我们分离出自突触反应，发现这些反应主要发生在投射到皮质下区域的第 5 层 PCs 中，而投射到对侧前额叶皮层和第 2/3 层 PCs 的非常少。此外，PC 自突触在发育到成年期时仍然存在。令人惊讶的是，它们产生的巨大的突触后反应（比 PC-PC 突触的反应大 5 倍）仅由 AMPA 受体介导。自突触激活后，增强爆发式放电、神经元反应性和突触输入的同时检测。这些发现表明 PC 自突触是功能性的，是新皮层中的一个重要电路元件。
