High contrast voltage imaging

Summary: There has been great interest – and tremendous progress – in the development of genetically encoded fluorescent voltage indicators (GEVIs) for observing the dynamics of neurons in the brain.  GEVIs have the potential to report the subthreshold and suprathreshold dynamics of neural populations with single-cell resolution and millisecond temporal precision. However, GEVI imaging requires fast (~kHz), high signal-to-noise imaging that is difficult to achieve with currently available techniques, particularly when cells are densely labeled.

We are working on different strategies to improve contrast and SNR when performing GEVI imaging. One technique involves the combination of targeted illumination combined with fast sCMOS camera imaging. Another technique involves the use of multi-z imaging with confocal (MuZIC) using a polygon scanner. Yet another technique involves the combination of targeted illumination and line-scan confocal microscopy (TICO). These techniques improve contrast compared to widefield imaging and achieve kilohertz frame rates. MuZIC provides the advantage of simultaneous multiplane imaging. TICO provides the advantage of high SNR imaging over large fields of view with reduced neuronal crosstalk, enabling routine in-vivo imaging of different GEVI types (e.g. somArchon, Voltron2) at depths of 300 microns.

  • S. Xiao, W. Cunningham, K. Kondabolu, E. Lowet, M. Moya, R. Mount, C. Ravasio, M. Economo, X. Han, J. Mertz, “Large-scale deep tissue voltage imaging with targeted illumination confocal microscopy”, bioRxiv, doi:
  • T. D. Weber, M. V. Moya, K. Kilic, J. Mertz, M. N. Economo, “High-speed multiplane confocal microscopy for voltage imaging in densely labeled neuronal populations”, Nat. Neurosci. https://doi.org/10.1038/s41593-023-01408-2 (2023)
  • S. Xiao, E. Lowet, H. J. Gritton, P Fabris, Y. Wang, J. Sherman, R. A. Mount, H.-a Tseng, H.-Y Man, C. Straub, K. D. Piatkevich, E. S. Boyden, J.Mertz, X. Han, “Large-scale voltage imaging in behaving mice using targeted illumination”, iScience 24, 103263 (2021). link
In vivo imaging of somArchon and Voltron2 with TICO microscopy

Multiplane imaging of Voltron2
MuZIC improves contrast (left, center) and provides simultaneous multiplane imaging (right)