6) neurons were labeled using this approach, but they could be distinguished based on the presence or absence of dendritic spines. Post hoc immunolabeling further identified the imaged cells. For specific labeling of parvalbumin interneurons (Fig. 6g and Supplementary Fig. 12), Cre-dependent GCaMP6s AAV was injected into the visual cortex of PV-IRES-Cre mice57. Individual somata (Supplementary Fig. 12) and dendritic segments could be recognized (Fig. 6 g, h, total length of imaged dendrite: 2.86 mm), but the high labeling density made it difficult to track individual dendrites over long distances.
