Developmental Synaptic Plasticity Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
Neuron. 2011 May 12;70(3):510-21. doi: 10.1016/j.neuron.2011.02.057.
Local recurrent excitatory circuits are ubiquitous in neocortex, yet little is known about their development or architecture. Here we introduce a quantitative technique for efficient single-cell resolution circuit mapping using 2-photon (2P) glutamate uncaging and analyze experience-dependent neonatal development of the layer 4 barrel cortex local excitatory circuit. We show that sensory experience specifically drives a 3-fold increase in connectivity at postnatal day (P) 9, producing a highly recurrent network. A profound dendritic spinogenesis occurs concurrent with the connectivity increase, but this is not experience dependent. However, in experience-deprived cortex, a much greater proportion of spines lack postsynaptic AMPA receptors (AMPARs) and synaptic connectivity via NMDA receptors (NMDARs) is the same as in normally developing cortex. Thus we describe a approach for quantitative circuit mapping and show that sensory experience sculpts an intrinsically developing template network, which is based on NMDAR-only synapses, by driving AMPARs into newly formed silent spines.
局部兴奋回路在新皮质中普遍存在，但人们对其发育或结构知之甚少。在这里，我们介绍了一种使用双光子（2P）谷氨酸光解进行高效单细胞分辨率回路映射的定量技术，并分析了层 4 桶状皮层局部兴奋性回路的经验依赖性新生儿发育。我们表明，感觉经验特异性地在出生后第 9 天（P）增加 3 倍的连接性，产生一个高度重复的网络。与连接性增加同时发生的是深刻的树突棘发生，但这不是经验依赖性的。然而，在剥夺经验的皮质中，更大比例的棘突缺乏突触后 AMPA 受体（AMPAR），通过 NMDA 受体（NMDAR）的突触连接与正常发育的皮质相同。因此，我们描述了一种定量回路映射的方法，并表明感觉经验通过将 AMPAR 引入新形成的沉默棘突来塑造内在发育的模板网络，该网络基于 NMDAR 单突触。
