在体单突触水平解析丘脑对视觉皮层的激活

We devised a multistep approach to study visual stimulation–activated synapses in orientation-tuned L4 pyramidal neurons in vivo. First, we performed population Ca2+ imaging (19, 20) in L4 of mouse V1, using the synthetic Ca2+ indicator Cal-520, to identify neurons highly tuned to specific orientations of drifting grating stimuli (Fig. 1, A to C). These neurons represent the majority of pyramidal neurons in L4 (21). Next, we delivered DNA plasmids to express the genetically encoded Ca2+ indicator (GECI) jGCaMP7b in one of the selected orientation-tuned L4 neurons (Fig. 1, D and F). The extremely sparse labeling with only one or two electroporated cells per mouse allowed for single-spine recordings in L4 with a high signal-to-noise ratio (22, 23). …