Adam, YoavKim, Jeong J.Lou, ShanZhao, YongxinXie, Michael E.Brinks, DaanWu, HaoMostajo-Radji, Mohammed A.Kheifets, SimonParot, VicenteChettih, SelmaanWilliams, Katherine J.Gmeiner, BenjaminFarhi, Samouil L.Madisen, LindaBuchanan, E. KellyKinsella, IanZhou, DingPaninski, LiamHarvey, Christopher D.Zeng, HongkuiArlotta, PaolaCampbell, Robert E.Cohen, Adam2020-04-092019-05Adam, Y., Kim, J.J., Lou, S. et al. Voltage imaging and optogenetics reveal behaviour-dependent changes in hippocampal dynamics. Nature 569, 413–417 (2019). https://doi.org/10.1038/s41586-019-1166-70028-08361476-4687http://nrs.harvard.edu/urn-3:HUL.InstRepos:42658795A technology to record membrane potential from multiple neurons, simultaneously, in behaving animals will have a transformative impact on neuroscience research1, 2. Genetically encoded voltage indicators are a promising tool for these purposes, but were so far limited to single-cell recordings with marginal signal to noise ratio (SNR) in vivo3-5. We developed improved near infrared voltage indicators, high speed microscopes and targeted gene expression schemes which enabled recordings of supra- and subthreshold voltage dynamics from multiple neurons simultaneously in mouse hippocampus, in vivo. The reporters revealed sub-cellular details of back-propagating action potentials and correlations in sub-threshold voltage between multiple cells. In combination with optogenetic stimulation, the reporters revealed brain state-dependent changes in neuronal excitability, reflecting the interplay of excitatory and inhibitory synaptic inputs. These tools open the possibility for detailed explorations of network dynamics in the context of behavior.en-USMultidisciplinaryJournal Article2020-04-0910.1038/s41586-019-1166-7