Imaging different cell populations in the mouse olfactory bulb using the genetically encoded voltage indicator ArcLight

Abstract

. Genetically encoded voltage indicators (GEVIs) are protein-based optical sensors that allow for measurements from genetically defined populations of neurons. Although in vivo imaging in the mammalian brain with early generation GEVIs was difficult due to poor membrane expression and low signal-to-noise ratio, newer and more sensitive GEVIs have begun to make them useful for answering fundamental questions in neuroscience. We discuss principles of imaging using GEVIs and genetically encoded calcium indicators, both useful tools for in vivo imaging of neuronal activity, and review some of the recent mechanistic advances that have led to GEVI improvements. We provide an overview of the mouse olfactory bulb (OB) and discuss recent studies using the GEVI ArcLight to study different cell types within the bulb using both widefield and two-photon microscopy. Specific emphasis is placed on using GEVIs to begin to study the principles of concentration coding in the OB, how to interpret the optical signals from population measurements in the in vivo brain, and future developments that will push the field forward.

Recent odor experience selectively modulates olfactory sensitivity across the glomerular output in the mouse olfactory bulb

“…Therefore, it seems possible that some proportion of calcium measurement from mitral/tufted glomeruli could reflect subthreshold activity. Future experiments would benefit from development of genetically encoded voltage indicators that are specifically tuned to supra-threshold voltage changes to allow for unambiguous optical measurements of spiking activity from mitral/tufted apical dendrites innervating a glomerulus [47].…”