title: Exploration of genetically encoded voltage indicators based on a chimeric voltage sensing domain.
abstract: Deciphering how the brain generates cognitive function from patterns of electrical signals is one of the ultimate challenges in neuroscience. To this end, it would be highly desirable to monitor the activities of very large numbers of neurons while an animal engages in complex behaviors. Optical imaging of electrical activity using genetically encoded voltage indicators (GEVIs) has the potential to meet this challenge. Currently prevalent GEVIs are based on the voltage-sensitive fluorescent protein (VSFP) prototypical design or on the voltage-dependent state transitions of microbial opsins. We recently introduced a new VSFP design in which the voltage-sensing domain (VSD) is sandwiched between a fluorescence resonance energy transfer pair of fluorescent proteins (termed VSFP-Butterflies) and also demonstrated a series of chimeric VSD in which portions of the VSD of Ciona intestinalis voltage-sensitive phosphatase are substituted by homologous portions of a voltage-gated potassium channel subunit. These chimeric VSD had faster sensing kinetics than that of the native Ci-VSD. Here, we describe a new set of VSFPs that combine chimeric VSD with the Butterfly structure. We show that these chimeric VSFP-Butterflies can report membrane voltage oscillations of up to 200 Hz in cultured cells and report sensory evoked cortical population responses in living mice. This class of GEVIs may be suitable for imaging of brain rhythms in behaving mammalians.
authors.affiliation: Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako, Japan ; Centre for Global Communication Strategies, The University of Tokyo Tokyo, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Mishina
authors.affiliation: Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako, Japan ; Department of Neurophysiology, Hamamatsu University School of Medicine Shizuoka, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Mutoh
authors.affiliation: Division of Brain Sciences, Department of Medicine, Imperial College London London, UK.
authors.forename: Chenchen
authors.initials: C
authors.lastname: Song
authors.affiliation: Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako, Japan ; Division of Brain Sciences, Department of Medicine, Imperial College London London, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Knöpfel
keywords: FRET sensors; mouse model; optical imaging; optogenetics; voltage imaging