With the recent breakthrough in genetically expressed voltage indicators (GEVIs), there has been a tremendous demand to determine the capabilities of these sensors in vivo. Novel voltage sensitive fluorescent proteins allow for direct measurement of neuron membrane potential changes through changes in fluorescence. Here, we utilized ArcLight, a recently developed GEVI, and examined the functional characteristics in the widely used mouse somatosensory whisker pathway. We measured the resulting evoked fluorescence using a wide-field microscope and a CCD camera at 200 Hz, which enabled voltage recordings over the entire cortical region with high temporal resolution. We found that ArcLight produced a fluorescent response in the S1 barrel cortex during sensory stimulation at single whisker resolution. During wide-field cortical imaging, we encountered substantial hemodynamic noise that required additional post hoc processing through noise subtraction techniques. Over a period of 28 days, we found clear and consistent ArcLight fluorescence responses to a simple sensory input. Finally, we demonstrated the use of ArcLight to resolve cortical S1 sensory responses in the awake mouse. Taken together, our results demonstrate the feasibility of ArcLight as a measurement tool for mesoscopic, chronic imaging.
Bibliographical noteFunding Information:
This paper was supported by the National Institute of Neurological Disorders and Stroke (NINDS): Award Nos. R01NS48285 (PI: G.B. Stanley), R01NS085447 (PI: G. B. Stanley), U01NS094302 (PI: D. Jaeger, and G.B. Stanley), and NS09869 (PI: P.Y. Borden); National Institute of Mental Health (NIMH): Award No. U01MH106027 (PI: G.B. Stanley, C.R. Forest). The authors would like to thank William Stoy, Ilya Kolb, and Timothy Lee, as well as other members of the Precision Biosystems Lab at Georgia Tech, for additional support and advice on imaging. Additionally, we thank Kyle Blum for feedback on imaging analysis and illustrations. We would also like to acknowledge He Zheng for pilot work on the ArcLight imaging. Furthermore, we would like to thank Vincent A. Pieribone for supplying us with the initial ArcLight protein and for imaging advice.
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).
- Genetically expressed voltage indicator
- In vivo
- Voltage sensor