Population signals from neuronal ensembles in cortex during behaviour are commonly measured with EEG, LFP and voltage-sensitive dyes. A genetically encoded voltage indicator would be useful for detection of such signals in specific cell types. Here, we describe how his goal can be achieved with Butterfly, a voltage-sensitive fluorescent protein (VSFP) with a subthreshold detection range and enhancements designed for the voltage imaging from single neurons to brain in vivo. VSFP-Butterfly showed reliable membrane targeting, maximum response gain around standard neuronal resting membrane potential, fast kinetics for single cell synaptic responses, and a high signal/noise ratio. Butterfly reports EPSPs in cortical neurons, whisker-evoked responses in barrel cortex, 25 Hz gamma oscillations in hippocampal slices, 2-12 Hz slow waves during brain state modulation in vivo. Our findings demonstrate that cell class specific voltage imaging is practical with VSFP-Butterfly, and expand the genetic toolbox for the detection of neuronal population dynamics.

  • Optical imaging
  • Cell class specificity
  • EEG
  • LFP
  • voltage sensitive dyes