In Vivo Imaging of Odor-Evoked Responses in the Olfactory Bulb using Arclight, a Novel Fp Voltage Probe

Abstract

Optogenetic reporters of membrane potential allow for recording of genetically distinct populations of neurons, although their usefulness to date has been limited by poor in vivo expression, small signal sizes and slow kinetics. The recently developed fluorescent protein (FP) voltage probe ArcLight exhibits a change in fluorescence to a 100 mV depolarization five times larger than previously reported probes in HEK 293 cells. However, recordings of ArcLight in mammalian neurons have been limited to cultured neurons. To demonstrate the utility of this probe in an in vivo preparation, AAV-1 viral transduction was used to express ArcLight in the mouse olfactory bulb. Different odors were presented, and the resulting patterns of activation were imaged and compared with those recorded from the optogenetic calcium indicator GCaMP3. Odor-specific patterns of activation were imaged from both ArcLight and GCaMP3, indicating that the FP voltage sensor ArcLight can be used as a reliable detector of odor-evoked population signals in the mouse olfactory bulb. Supported by US NIH Grants DC005259 and NS057631 and grant WCI 2009-003 from the National Research Foundation of Korea.