Kavli Affiliate: Attila Losonczy
| Authors: S. Wenceslao Evans, Dongqing Shi, Mariya Chavarha, Mark H. Plitt, Jiannis Taxidis, Blake Madruga, Siri C. van Keulen, Michelle M. Pang, Sharon Su, Fuu-Jiun Hwang, Guofeng Zhang, Austin Reese, Lagnajeet Pradhan, Jiang Lan Fan, Sungmoo Lee, Yu Liu, Carl-Mikael Suomivuori, Dongyun Jiang, Adrian Negrean, Sui Wang, Na Ji, Thomas R. Clandinin, Ron O. Dror, Guoqiang Bi, Christopher D. Makinson, Peyman Golshani, Lisa M. Giocomo, Attila Losonczy, Jun B. Ding and Michael Z. Lin
| Summary:
Abstract Neuronal spiking activity is routinely recorded using genetically encoded calcium indicators (GECIs), but calcium imaging is limited in temporal resolution and does not report subthreshold voltage changes. Genetically encoded voltage indicators (GEVIs) offer better temporal resolution and subthreshold sensitivity, but spike detection with fast GEVIs has required specialized imaging equipment. Here, we report the ASAP4 subfamily of genetically encoded voltage indicators (GEVIs) that brighten in response to membrane depolarization, inverting the fluorescence-voltage relationship of previous ASAP GEVIs. Two variants, ASAP4b and ASAP4e, feature 128% and 178% fluorescence increases over 100-mV of depolarization, respectively, facilitating spike detection in single trials in vivo with standard 1 and 2-photon imaging systems. Simultaneous voltage and calcium imaging confirms improved temporal resolution and spike discernment by ASAP4 GEVIs. Thus, positively tuned ASAP4 voltage indicators enable recording of neuronal spiking activity using similar equipment as calcium imaging, while providing higher temporal resolution. One Sentence Summary Upward ASAPs increase detection capability of GEVIs in vivo. Competing Interest Statement M.Z.L. is an inventor on patent US9606100 describing ASAP1.